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Sample records for low-temperature selective catalytic

  1. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  2. Enhanced catalytic activity over MIL-100(Fe) loaded ceria catalysts for the selective catalytic reduction of NOx with NH₃ at low temperature.

    Science.gov (United States)

    Wang, Peng; Sun, Hong; Quan, Xie; Chen, Shuo

    2016-01-15

    The development of catalysts for selective catalytic reduction (SCR) reactions that are highly active at low temperatures and show good resistance to SO2 and H2O is still a challenge. In this study, we have designed and developed a high-performance SCR catalyst based on nano-sized ceria encapsulated inside the pores of MIL-100(Fe) that combines excellent catalytic power with a metal organic framework architecture synthesized by the impregnation method (IM). Transmission electron microscopy (TEM) revealed the encapsulation of ceria in the cavities of MIL-100(Fe). The prepared IM-CeO2/MIL-100(Fe) catalyst shows improved catalytic activity both at low temperatures and throughout a wide temperature window. The temperature window for 90% NOx conversion ranges from 196 to 300°C. X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analysis indicated that the nano-sized ceria encapsulated inside MIL-100(Fe) promotes the production of chemisorbed oxygen on the catalyst surface, which greatly enhances the formation of the NO2 species responsible for fast SCR reactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Enhanced catalytic activity over MIL-100(Fe) loaded ceria catalysts for the selective catalytic reduction of NO{sub x} with NH{sub 3} at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng [School of Environmental Science and Technology, Dalian University of Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), Dalian 116024 (China); Sun, Hong [School of Environmental & Chemical Engineering, Dalian Jiaotong University, Dalian 116028 (China); Quan, Xie, E-mail: quanxie@dlut.edu.cn [School of Environmental Science and Technology, Dalian University of Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), Dalian 116024 (China); Chen, Shuo [School of Environmental Science and Technology, Dalian University of Technology, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), Dalian 116024 (China)

    2016-01-15

    Highlights: • Nano-ceria was successfully encapsulated into MIL-100(Fe) for the SCR of NO{sub x}. • The incorporated ceria in MIL-100(Fe) showed high content of chemisorbed oxygen. • The added ceria into MIL-100(Fe) improved the formation of adsorbed NO{sub 2} species. • The addition of ceria into MIL-100(Fe) enhanced SCR activity at low temperature. - Abstract: The development of catalysts for selective catalytic reduction (SCR) reactions that are highly active at low temperatures and show good resistance to SO{sub 2} and H{sub 2}O is still a challenge. In this study, we have designed and developed a high-performance SCR catalyst based on nano-sized ceria encapsulated inside the pores of MIL-100(Fe) that combines excellent catalytic power with a metal organic framework architecture synthesized by the impregnation method (IM). Transmission electron microscopy (TEM) revealed the encapsulation of ceria in the cavities of MIL-100(Fe). The prepared IM-CeO{sub 2}/MIL-100(Fe) catalyst shows improved catalytic activity both at low temperatures and throughout a wide temperature window. The temperature window for 90% NO{sub x} conversion ranges from 196 to 300 °C. X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analysis indicated that the nano-sized ceria encapsulated inside MIL-100(Fe) promotes the production of chemisorbed oxygen on the catalyst surface, which greatly enhances the formation of the NO{sub 2} species responsible for fast SCR reactions.

  4. Alumina- and titania-based monolithic catalysts for low temperature selective catalytic reduction of nitrogen oxides

    International Nuclear Information System (INIS)

    Blanco, J.; Avila, P.; Suarez, S.; Martin, J.A.; Knapp, C.

    2000-01-01

    The selective catalytic reduction of NO+NO 2 (NO x ) at low temperature (180-230C) with ammonia has been investigated with copper-nickel and vanadium oxides supported on titania and alumina monoliths. The influence of the operating temperature, as well as NH 3 /NO x and NO/NO 2 inlet ratios has been studied. High NO x conversions were obtained at operating conditions similar to those used in industrial scale units with all the catalysts. Reaction temperature, ammonia and nitrogen dioxide inlet concentration increased the N 2 O formation with the copper-nickel catalysts, while no increase was observed with the vanadium catalysts. The vanadium-titania catalyst exhibited the highest DeNO x activity, with no detectable ammonia slip and a low N 2 O formation when NH 3 /NO x inlet ratio was kept below 0.8. TPR results of this catalyst with NO/NH 3 /O 2 , NO 2 /NH 3 /O 2 and NO/NO 2 /NH 3 /O 2 feed mixtures indicated that the presence of NO 2 as the only nitrogen oxide increases the quantity of adsorbed species, which seem to be responsible for N 2 O formation. When NO was also present, N 2 O formation was not observed

  5. Low-temperature catalytic conversion of carbonaceous materials

    Directory of Open Access Journals (Sweden)

    Tabakaev Roman B.

    2015-01-01

    Full Text Available Laws of the rate of carbon conversion in steam atmosphere at a temperature in modes of the catalytic low-temperature treatment of peat, brown coal, semi-coke from peat and brown coal are obtained by experiments. Increasing of the rate of carbon conversion in temperature range up to 500 °C is achieved by using of catalysts. The possibility of using results is associated with the burners, a working zone of which is porous filling from carbonaceous particles.

  6. Catalytic Palladium Film Deposited by Scalable Low-Temperature Aqueous Combustion.

    Science.gov (United States)

    Voskanyan, Albert A; Li, Chi-Ying Vanessa; Chan, Kwong-Yu

    2017-09-27

    This article describes a novel method for depositing a dense, high quality palladium thin film via a one-step aqueous combustion process which can be easily scaled up. Film deposition of Pd from aqueous solutions by conventional chemical or electrochemical methods is inhibited by hydrogen embrittlement, thus resulting in a brittle palladium film. The method outlined in this work allows a direct aqueous solution deposition of a mirror-bright, durable Pd film on substrates including glass and glassy carbon. This simple procedure has many advantages including a very high deposition rate (>10 cm 2 min -1 ) and a relatively low deposition temperature (250 °C), which makes it suitable for large-scale industrial applications. Although preparation of various high-quality oxide films has been successfully accomplished via solution combustion synthesis (SCS) before, this article presents the first report on direct SCS production of a metallic film. The mechanism of Pd film formation is discussed with the identification of a complex formed between palladium nitrate and glycine at low temperature. The catalytic properties and stability of films are successfully tested in alcohol electrooxidation and electrochemical oxygen reduction reaction. It was observed that combustion deposited Pd film on a glassy carbon electrode showed excellent catalytic activity in ethanol oxidation without using any binder or additive. We also report for the first time the concept of a reusable "catalytic flask" as illustrated by the Suzuki-Miyaura cross-coupling reaction. The Pd film uniformly covers the inner walls of the flask and eliminates the catalyst separation step. We believe the innovative concept of a reusable catalytic flask is very promising and has the required features to become a commercial product in the future.

  7. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E; Roth, F von; Hottinger, P; Truong, T B [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  8. Integrated Removal of NOx with Carbon Monoxide as Reductant, and Capture of Mercury in a Low Temperature Selective Catalytic and Adsorptive Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Neville Pinto; Panagiotis Smirniotis; Stephen Thiel

    2010-08-31

    Coal will likely continue to be a dominant component of power generation in the foreseeable future. This project addresses the issue of environmental compliance for two important pollutants: NO{sub x} and mercury. Integration of emission control units is in principle possible through a Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR) in which NO{sub x} removal is achieved in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The capture of mercury is integrated into the same process unit. Such an arrangement would reduce mercury removal costs significantly, and provide improved control for the ultimate disposal of mercury. The work completed in this project demonstrates that the use of CO as a reductant in LTSCR is technically feasible using supported manganese oxide catalysts, that the simultaneous warm-gas capture of elemental and oxidized mercury is technically feasible using both nanostructured chelating adsorbents and ceria-titania-based materials, and that integrated removal of mercury and NO{sub x} is technically feasible using ceria-titania-based materials.

  9. The Poisoning Effect of Na Doping over Mn-Ce/TiO2 Catalyst for Low-Temperature Selective Catalytic Reduction of NO by NH3

    Directory of Open Access Journals (Sweden)

    Liu Yang

    2014-01-01

    Full Text Available Sodium carbonate (Na2CO3, sodium nitrate (NaNO3, and sodium chloride (NaCl were chosen as the precursors to prepare the Na salts deposited Mn-Ce/TiO2 catalysts through an impregnation method. The influence of Na on the performance of the Mn-Ce/TiO2 catalyst for low-temperature selective catalytic reduction of NOx by NH3 was investigated. Experimental results showed that Na salts had negative effects on the activity of Mn-Ce/TiO2 and the precursors of Na salts also affected the catalytic activity. The precursor Na2CO3 had a greater impact on the catalytic activity, while NaNO3 had minimal effect. The characterization results indicated that the significant changes in physical and chemical properties of Mn-Ce/TiO2 were observed after Na was doped on the catalysts. The significant decreases in surface areas and NH3 adsorption amounts were observed after Na was doped on the catalysts, which could be considered as the main reasons for the deactivation of Na deposited Mn-Ce/TiO2.

  10. Hybrid selective noncatalytic reduction (SNCR)/selective catalytic reduction (SCR) for NOx removal using low-temperature SCR with Mn-V2O5/TiO2 catalyst.

    Science.gov (United States)

    Choi, Sung-Woo; Choi, Sang-Ki; Bae, Hun-Kyun

    2015-04-01

    A hybrid selective noncatalytic reduction/selective catalytic reduction (SNCR/SCR) system that uses two types of technology, low-temperature SCR process and SNCR process, was designed to develop nitrogen oxide (NOx) reduction technology. SCR was conducted with space velocity (SV)=2400 hr(-1) and hybrid SNCR/SCR with SV=6000 hr(-1), since the study focused on reducing the amount of catalyst and both achieved 98% NOx reduction efficiency. Characteristics of NOx reduction by NH3 were studied for low-temperature SCR system at 150 °C using Mn-V2O5/TiO2 catalyst. Mn-added V2O5/TiO2 catalyst was produced, and selective catalyst reduction of NOx by NH3 was experimented. NOx reduction rate according to added Mn content in Mn-V2O5/TiO2 catalyst was studied with varying conditions of reaction temperature, normalized stoichiometric ratio (NSR), SV, and O2 concentration. In the catalyst experiment according to V2O5 concentration, 1 wt.% V2O5 catalyst showed the highest NOx reduction rate: 98% reduction at temperature window of 200~250 °C. As a promoter of the V2O5 catalyst, 5 wt.% Mn was added, and the catalyst showed 47~90% higher efficiency even with low temperatures, 100~200 °C. Mn-V2O5/TiO2 catalyst, prepared by adding 5 wt.% Mn in V2O5/TiO2 catalyst, showed increments of catalyst activation at 150 °C as well as NOx reduction. Mn-V2O5/TiO2 catalyst showed 8% higher rate for NOx reduction compared with V2O5/TiO2 catalyst in 150 °C SCR. Thus, (5 wt.%)Mn-(1 wt.%)V2O5/TiO2 catalyst was applied in SCR of hybrid SNCR/SCR system of low temperature at 150 °C. Low-temperature SCR hybrid SNCR/SCR (150 °C) system and hybrid SNCR/SCR (350 °C) showed 91~95% total reduction rate with conditions of SV=2400~6000 hr(-1) SCR and 850~1050 °C SNCR, NSR=1.5~2.0, and 5% O2. Hybrid SNCR/SCR (150 °C) system proved to be more effective than the hybrid SNCR/SCR (350 °C) system at low temperature. NOx control is very important, since they are the part of greenhouse gases as well as the

  11. Mn/TiO2 and Mn–Fe/TiO2 catalysts synthesized by deposition precipitation—promising for selective catalytic reduction of NO with NH3 at low temperatures

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Schill, Leonhard; Jensen, Anker Degn

    2015-01-01

    Mn/TiO2and Mn–Fe/TiO2catalysts have been prepared by impregnation (IMP) and deposition-precipitation (DP) techniques and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR, XPS and TGA. 25 wt% Mn0.75Fe0.25Ti-DP catalyst, prepared by deposition precipitation with ammonium carbamate (AC......) as a precipitating agent, showed superior low-temperature SCR (selective catalytic reduction) of NO with NH3. The superior catalytic activity of the 25 wt% Mn0.75Fe0.25Ti-DP catalyst is probably due to the presence of amorphous phases of manganese oxide, iron oxide, high surface area, high total acidity......, acidstrength and ease of reduction of manganese oxide and iron oxide on TiO2in addition to formation of an SCR active MnOx phase with high content of chemisorbed oxygen (Oα). The optimum catalyst might beused as tail-end SCR catalysts in, e.g., biomass-fired power plants and waste incineration plants....

  12. Improving carbon tolerance of Ni-YSZ catalytic porous membrane by palladium addition for low temperature steam methane reforming

    Science.gov (United States)

    Lee, Sang Moon; Won, Jong Min; Kim, Geo Jong; Lee, Seung Hyun; Kim, Sung Su; Hong, Sung Chang

    2017-10-01

    Palladium was added on the Ni-YSZ catalytic porous membrane by wet impregnation and electroless plating methods. Its surface morphology characteristics and carbon deposition properties for the low temperature steam methane reforming were investigated. The addition of palladium could obviously be enhanced the catalytic activity as well as carbon tolerance of the Ni-YSZ porous membrane. The porous membranes were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), CH4 temperature-programmed reduction (CH4-TPR), and O2 temperature-programmed oxidation (O2-TPO). It was found that the Pd-Ni-YSZ catalytic porous membrane showed the superior stability as well as the deposition of carbon on the surface during carbon dissociation adsorption at 650 °C was also suppressed.

  13. Effect of metal ions doping (M = Ti4+, Sn4+) on the catalytic performance of MnOx/CeO2 catalyst for low temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Xiong, Yan; Tang, Changjin; Dong, Lin

    2015-04-01

    Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China The abatement of nitrogen oxides (NOx) emission from exhaust gases of diesel and stationary sources is a significant challenge for economic and social development. Ceria-based solid solutions were synthesized and used as supports to prepare MnOx/Ce0.8Ti0.2O2 and MnOx/Ce0.8Sn0.2O2 catalysts (Mn/CeTi and Mn/CeSn) for low temperature selective catalytic reduction of NO by NH3 (NH3-SCR). The effects of Ti or Sn doping on the catalytic performance of MnOx/CeO2 catalyst were investigated. Experimental results show that doping of Ti or Sn increases the NO removal efficiency of MnOx/CeO2. The NO conversion of Mn/CeTi catalyst is more than 90 % at temperature window of 175 ~ 300 °C under a gas hour space velocity of 60,000 mL.g-1.h-1. Modified catalysts are also found to exhibit greatly improved resistance to sulfur-poisoning. NH3-TPD results suggest that NH3 desorption on the catalysts is observed over a wide temperature range, due to the variability of adsorbed NH3 species with different thermal stabilities. Doping of Ti and Sn into Mn/CeO2 greatly increased the NH3 adsorption ability of the composites which could promote the SCR reaction. Characterization results also indicate that doping of Ti or Sn brings about catalysts with higher BET surface area, enhanced oxygen storage capacity and increased surface acidity.

  14. Low temperature catalytic combustion of propane over Pt-based catalyst with inverse opal microstructure in microchannel reactor

    NARCIS (Netherlands)

    Guan, G.; Zapf, R.; Kolb, G.A.; Men, Y.; Hessel, V.; Löwe, H.; Ye, J.; Zentel, R.

    2007-01-01

    novel Pt-based catalyst with highly regular, periodic inverse opal microstructure was fabricated in a microchannel reactor, and catalytic testing revealed excellent conversion and stable activity for propane combustion at low temperatures

  15. In situ IR studies of Co and Ce doped Mn/TiO{sub 2} catalyst for low-temperature selective catalytic reduction of NO with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Lu; Pang, Dandan; Zhang, Changliang; Meng, Jiaojiao; Zhu, Rongshu; Ouyang, Feng, E-mail: ouyangfh@hit.edu.cn

    2015-12-01

    Highlights: • A SCR mechanistic pathway over Mn–Co–Ce/TiO{sub 2} is proposed. • The cobalt oxide produces lots of Brønsted acid sites, which favor to the adsorption of coordinated NH{sub 3} through NH{sub 3} migration. • Ce addition improves amide ions formation to reach best NO reduction selectivity. • At low-temperature coordinated NH{sub 3} reacts with NO{sub 2}{sup −}, or amide reacts with NO (ad) or NO (g) to form N{sub 2}. At high temperature, the reaction also occurs between coordinated NH{sub 3} and nitrate species. - Abstract: The Mn–Co–Ce/TiO{sub 2} catalyst was prepared by wet co-impregnation method for selective catalytic reduction of NO by NH{sub 3} in the presence of oxygen. The adsorption and co-adsorption of NH{sub 3}, NO and O{sub 2} on catalysts were investigated by in situ FTIR spectroscopy. The results suggested that addition of cobalt and cerium oxides increased the numbers of acid and redox sites. Especially, the cobalt oxide produced lots of Brønsted acid sites, which favor to the adsorption of coordinated NH{sub 3} through NH{sub 3} migration. Ce addition improved amide ions formation to reach best NO reduction selectivity. A mechanistic pathway over Mn–Co–Ce/TiO{sub 2} was proposed. At low-temperature SCR reaction, coordinated NH{sub 3} reacted with NO{sub 2}{sup −}, and amide reacted with NO (ad) or NO (g) to form N{sub 2}. NO{sub 2} was related to the formation of nitrite on Co-contained catalysts and the generation of −NH{sub 2}{sup −} on Ce-contained catalysts. At high temperature, the other branch reaction also occurred between the coordinated NH{sub 3} and nitrate species, resulting in N{sub 2}O yield increase.

  16. Real-world exhaust temperature profiles of on-road heavy-duty diesel vehicles equipped with selective catalytic reduction.

    Science.gov (United States)

    Boriboonsomsin, Kanok; Durbin, Thomas; Scora, George; Johnson, Kent; Sandez, Daniel; Vu, Alexander; Jiang, Yu; Burnette, Andrew; Yoon, Seungju; Collins, John; Dai, Zhen; Fulper, Carl; Kishan, Sandeep; Sabisch, Michael; Jackson, Doug

    2018-09-01

    On-road heavy-duty diesel vehicles are a major contributor of oxides of nitrogen (NO x ) emissions. In the US, many heavy-duty diesel vehicles employ selective catalytic reduction (SCR) technology to meet the 2010 emission standard for NO x . Typically, SCR needs to be at least 200°C before a significant level of NO x reduction is achieved. However, this SCR temperature requirement may not be met under some real-world operating conditions, such as during cold starts, long idling, or low speed/low engine load driving activities. The frequency of vehicle operation with low SCR temperature varies partly by the vehicle's vocational use. In this study, detailed vehicle and engine activity data were collected from 90 heavy-duty vehicles involved in a range of vocations, including line haul, drayage, construction, agricultural, food distribution, beverage distribution, refuse, public work, and utility repair. The data were used to create real-world SCR temperature and engine load profiles and identify the fraction of vehicle operating time that SCR may not be as effective for NO x control. It is found that the vehicles participated in this study operate with SCR temperature lower than 200°C for 11-70% of the time depending on their vocation type. This implies that real-world NO x control efficiency could deviate from the control efficiency observed during engine certification. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NOx with NH3

    International Nuclear Information System (INIS)

    Szymanski, Grzegorz S.; Grzybek, Teresa; Papp, Helmut

    2004-01-01

    The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N 2 O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO 2 formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide

  18. Materials for High-Temperature Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ersson, Anders

    2003-04-01

    Catalytic combustion is an environmentally friendly technique to combust fuels in e.g. gas turbines. Introducing a catalyst into the combustion chamber of a gas turbine allows combustion outside the normal flammability limits. Hence, the adiabatic flame temperature may be lowered below the threshold temperature for thermal NO{sub X} formation while maintaining a stable combustion. However, several challenges are connected to the application of catalytic combustion in gas turbines. The first part of this thesis reviews the use of catalytic combustion in gas turbines. The influence of the fuel has been studied and compared over different catalyst materials. The material section is divided into two parts. The first concerns bimetallic palladium catalysts. These catalysts showed a more stable activity compared to their pure palladium counterparts for methane combustion. This was verified both by using an annular reactor at ambient pressure and a pilot-scale reactor at elevated pressures and flows closely resembling the ones found in a gas turbine combustor. The second part concerns high-temperature materials, which may be used either as active or washcoat materials. A novel group of materials for catalysis, i.e. garnets, has been synthesised and tested in combustion of methane, a low-heating value gas and diesel fuel. The garnets showed some interesting abilities especially for combustion of low-heating value, LHV, gas. Two other materials were also studied, i.e. spinels and hexa aluminates, both showed very promising thermal stability and the substituted hexa aluminates also showed a good catalytic activity. Finally, deactivation of the catalyst materials was studied. In this part the sulphur poisoning of palladium, platinum and the above-mentioned complex metal oxides has been studied for combustion of a LHV gas. Platinum and surprisingly the garnet were least deactivated. Palladium was severely affected for methane combustion while the other washcoat materials were

  19. Highly Selective Synthesis of Catalytically Active Monodisperse Rhodium Nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Grass, M.E.; Kuhn, J.N.; Tao, F.; Habas, S.E.; Huang, W.; Yang, P.; Somorjai, G.A.

    2009-02-21

    Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metal NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl

  20. Low-temperature catalytic gasification of wet industrial wastes

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D C; Neuenschwander, G G; Baker, E G; Sealock, Jr, L J; Butner, R S

    1991-04-01

    Bench-scale reactor tests are in progress at Pacific Northwest Laboratory to develop a low-temperature, catalytic gasification system. The system, licensed under the trade name Thermochemical Environmental Energy System (TEES{reg sign}), is designed for treating a wide variety of feedstocks ranging from dilute organics in water to waste sludges from food processing. This report describes a test program which used a continuous-feed tubular reactor. This test program is an intermediate stage in the process development. The reactor is a laboratory-scale version of the commercial concept as currently envisioned by the process developers. An energy benefit and economic analysis was also completed on the process. Four conceptual commercial installations of the TEES process were evaluated for three food processing applications and one organic chemical manufacturing application. Net energy production (medium-Btu gas) was achieved in all four cases. The organic chemical application was found to be economically attractive in the present situation. Based on sensitivity studies included in the analysis, the three food processing cases will likely become attractive in the near future as waste disposal regulations tighten and disposal costs increase. 21 refs., 2 figs., 9 tabs.

  1. Selective catalytic reduction of nitric oxide by ammonia over Cu-exchanged Cuban natural zeolites

    International Nuclear Information System (INIS)

    Moreno-Tost, Ramon; Santamaria-Gonzalez, Jose; Rodriguez-Castellon, Enrique; Jimenez-Lopez, Antonio; Autie, Miguel A.; Glacial, Marisol Carreras; Gonzalez, Edel; Pozas, Carlos De las

    2004-01-01

    The catalytic selective reduction of NO over Cu-exchanged natural zeolites (mordenite (MP) and clinoptilolite (HC)) from Cuba using NH 3 as reducing agent and in the presence of excess oxygen was studied. Cu(II)-exchanged zeolites are very active catalysts, with conversions of NO of 95%, a high selectivity to N 2 at low temperatures, and exhibiting good water tolerance. The chemical state of the Cu(II) in exchanged zeolites was characterized by H 2 -TPR and XPS. Cu(II)-exchanged clinoptilolite underwent a severe deactivation in the presence of SO 2 . However, Cu(II)-exchanged mordenite not only maintained its catalytic activity, but even showed a slight improvement after 20h of reaction in the presence of 100ppm of SO 2

  2. Low Temperature Steam Methane Reforming Over Ni Based Catalytic Membrane Prepared by Electroless Palladium Plating.

    Science.gov (United States)

    Lee, Sang Moon; Hong, Sung Chang; Kim, Sung Su

    2018-09-01

    A Pd/Ni-YSZ porous membrane with different palladium loadings and hydrazine as a reducing reagent was prepared by electroless plating and evaluated for the steam methane reforming activity. The steam-reforming activity of a Ni-YSZ porous membrane was greatly increased by the deposition of 4 g/L palladium in the low-temperature range (600 °C). With an increasing amount of reducing reagent, the Pd clusters were well dispersed on the Ni-YSZ surface and were uniform in size (∼500 nm). The Pd/Ni-YSZ catalytic porous membrane prepared by 1 of Pd/hydrazine ratio possessed an abundant amount of metallic Pd. The optimal palladium loadings and Pd/hydrazine ratio increased the catalytic activity in both the steam-reforming reaction and the Pd dispersion.

  3. The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

    OpenAIRE

    Shin, Yeonwoo; Kim, Sang Tae; Kim, Kuntae; Kim, Mi Young; Oh, Saeroonter; Jeong, Jae Kyeong

    2017-01-01

    High-mobility indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are achieved through low-temperature crystallization enabled via a reaction with a transition metal catalytic layer. For conventional amorphous IGZO TFTs, the active layer crystallizes at thermal annealing temperatures of 600??C or higher, which is not suitable for displays using a glass substrate. The crystallization temperature is reduced when in contact with a Ta layer, where partial crystallization at the IGZO bac...

  4. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco; Xie, Yihui; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2016-01-01

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco

    2016-02-29

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane\\'s ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NO{sub x} with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Szymanski, Grzegorz S. [Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Torun (Poland); Grzybek, Teresa [Faculty of Fuels and Energy, AGH, University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Papp, Helmut [Faculty of Chemistry and Mineralogy, Institute of Technical Chemistry, University of Leipzig, Linnerstrasse 3, 04103 Leipzig (Germany)

    2004-06-15

    The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N{sub 2}O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO{sub 2} formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide.

  7. Validation of the catalytic properties of Cu-Os/13X using single fixed bed reactor in selective catalytic reduction of NO

    International Nuclear Information System (INIS)

    Oh, Kwang Seok; Woo, Seong Ihl

    2007-01-01

    Catalytic decomposition of NO over Cu-Os/13X has been carried out in a tubular fixed bed reactor at atmospheric pressure and the results were compared with literature data performed by high-throughput screening (HTS). The activity and durability of Cu-Os/13X prepared by conventional ion-exchange method have been investigated in the presence of H 2 O and SO 2 . It was found that Cu-Os/13X prepared by ion-exchange shows a high activity in a wide temperature range in selective catalytic reduction (SCR) of NO with C 3 H 6 compared to Cu/13X, proving the existence of more NO adsorption site on Cu-Os/13X. However, Cu-Os/13X exhibited low activity in the presence of water, and was quite different from the result reported in literature. SO 2 resistance is also low and does not recover its original activity when the SO 2 was blocked in the feed gas stream. This result suggested that catalytic activity between combinatorial screening and conventional testing should be compared to confirm the validity of high-throughput screening

  8. The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer.

    Science.gov (United States)

    Shin, Yeonwoo; Kim, Sang Tae; Kim, Kuntae; Kim, Mi Young; Oh, Saeroonter; Jeong, Jae Kyeong

    2017-09-07

    High-mobility indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are achieved through low-temperature crystallization enabled via a reaction with a transition metal catalytic layer. For conventional amorphous IGZO TFTs, the active layer crystallizes at thermal annealing temperatures of 600 °C or higher, which is not suitable for displays using a glass substrate. The crystallization temperature is reduced when in contact with a Ta layer, where partial crystallization at the IGZO back-channel occurs with annealing at 300 °C, while complete crystallization of the active layer occurs at 400 °C. The field-effect mobility is significantly boosted to 54.0 cm 2 /V·s for the IGZO device with a metal-induced polycrystalline channel formed at 300 °C compared to 18.1 cm 2 /V·s for an amorphous IGZO TFT without a catalytic layer. This work proposes a facile and effective route to enhance device performance by crystallizing the IGZO layer with standard annealing temperatures, without the introduction of expensive laser irradiation processes.

  9. Low temperature and self catalytic growth of ultrafine ITO nanowires by electron beam evaporation method and their optical and electrical properties

    International Nuclear Information System (INIS)

    Kumar, R. Rakesh; Rao, K. Narasimha; Rajanna, K.; Phani, A.R.

    2014-01-01

    Highlights: • ITO nanowires were grown by e-beam evaporation method. • ITO nanowires growth done at low substrate temperature of 350 °C. • Nanowires growth was carried out without use of catalyst and reactive oxygen gas. • Nanowires growth proceeds via self catalytic VLS growth. • Grown nanowires have diameter 10–20 nm and length 1–4 μm long. • ITO nanowire films have shown good antireflection property. - Abstract: We report the self catalytic growth of Sn-doped indium oxide (ITO) nanowires (NWs) over a large area glass and silicon substrates by electron beam evaporation method at low substrate temperatures of 250–400 °C. The ITO NWs growth was carried out without using an additional reactive oxygen gas and a metal catalyst particle. Ultrafine diameter (∼10–15 nm) and micron long ITO NWs growth was observed in a temperature window of 300–400 °C. Transmission electron microscope studies confirmed single crystalline nature of the NWs and energy dispersive spectroscopy studies on the NWs confirmed that the NWs growth proceeds via self catalytic vapor-liquid-solid (VLS) growth mechanism. ITO nanowire films grown on glass substrates at a substrate temperature of 300–400 °C have shown ∼2–6% reflection and ∼70–85% transmission in the visible region. Effect of deposition parameters was systematically investigated. The large area growth of ITO nanowire films would find potential applications in the optoelectronic devices

  10. Low concentration volatile organic pollutants removal in combined adsorber-desorber-catalytic reactor system

    Directory of Open Access Journals (Sweden)

    Arsenijević Zorana

    2008-01-01

    Full Text Available The removal of volatile organic compounds (VOCs from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be­nign products, low energy consumption and absence of secondary polluti­on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.

  11. Efficient selective catalytic reduction of NO by novel carbon-doped metal catalysts made from electroplating sludge.

    Science.gov (United States)

    Zhang, Jia; Zhang, Jingyi; Xu, Yunfeng; Su, Huimin; Li, Xiaoman; Zhou, Ji Zhi; Qian, Guangren; Li, Li; Xu, Zhi Ping

    2014-10-07

    Electroplating sludges, once regarded as industrial wastes, are precious resources of various transition metals. This research has thus investigated the recycling of an electroplating sludge as a novel carbon-doped metal (Fe, Ni, Mg, Cu, and Zn) catalyst, which was different from a traditional carbon-supported metal catalyst, for effective NO selective catalytic reduction (SCR). This catalyst removed >99.7% NO at a temperature as low as 300 °C. It also removed NO steadily (>99%) with a maximum specific accumulative reduced amount (MSARA) of 3.4 mmol/g. Gas species analyses showed that NO removal was accompanied by evolving N2 and CO2. Moreover, in a wide temperature window, the sludge catalyst showed a higher CO2 selectivity (>99%) than an activated carbon-supported metal catalyst. Structure characterizations revealed that carbon-doped metal was transformed to metal oxide in the sludge catalyst after the catalytic test, with most carbon (2.33 wt %) being consumed. These observations suggest that NO removal over the sludge catalyst is a typical SCR where metals/metal oxides act as the catalytic center and carbon as the reducing reagent. Therefore, our report probably provides an opportunity for high value-added utilizations of heavy-metal wastes in mitigating atmospheric pollutions.

  12. The poisoning effect of PbO on Mn-Ce/TiO{sub 2} catalyst for selective catalytic reduction of NO with NH{sub 3} at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Lingling [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Li, Caiting, E-mail: ctli@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zhao, Lingkui; Zeng, Guangming; Gao, Lei; Wang, Yan; Yu, Ming’e [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

    2016-12-15

    Highlights: • The poisoning effects of PbO-doped Mn-Ce/TiO{sub 2} catalysts for low temperature NH{sub 3}-SCR were investigated. • Low concentration of Mn{sup 4+} and chemisorbed oxygen (O{sub b}) were not favorable for the generation of intermediates. • The decreased Ce{sup 3+} and less reducible of manganese oxides hindered the redox cycle (Mn{sup 3+} + Ce{sup 4+} ↔ Mn{sup 4+} + Ce{sup 3+}). • The doping of PbO not only altered acid sites but also inhibited ammonia adsorption as well as activation. • The poisoning of PbO resulted in the decrease of ad-NO{sub x} species (only a spot of bidentate nitrates remained). - Abstract: Lead oxide (PbO) as one of the typical heavy metals in flue gas from power plants has strong accumulation as well as poisoning effects on SCR catalysts. In this paper, a series of PbO-doped Mn-Ce/TiO{sub 2} catalysts were synthesized by impregnation method. The poisoning effects of PbO over Mn-Ce/TiO{sub 2} samples for selective catalytic reduction of NO by NH{sub 3} were investigated based on catalytic activity test and characterizations. The NO conversion of Mn-Ce/TiO{sub 2} was greatly decreased after the addition of PbO. It was obvious that the NO conversion efficiency of Mn-Ce/TiO{sub 2} catalyst declined from 96.75% to about 40% at 200 °C when Pb:Mn molar ratio reached 0.5. Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Hydrogen temperature programmed reduction (H{sub 2}-TPR), Ammonia temperature programmed desorption (NH{sub 3}-TPD) and Fourier transform infrared spectroscopy (FT-IR) were carried out to study the deactivation reasons of PbO poisoned catalysts. Manganese oxides’ crystallization, less reducible of manganese and cerium oxides, the decreasing of surface area, Mn{sup 4+} as well as Ce{sup 3+} concentration and chemisorbed oxygen (O{sub b}) after the introduction of PbO, all of these resulted in a poor SCR performance

  13. Synergy of CuO and CeO2 combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere

    KAUST Repository

    Li, Hailong

    2016-07-19

    Synergy for low temperature Hg0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO2/TiO2 (CuCeTi) catalyst. Hg0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect, comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO2 (CuTi), CeO2/TiO2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O2 to surface oxygen, which are favorable for Hg0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg0 oxidation in the absence of gas-phase O2. Cerium oxides in the combination promoted Hg0 oxidation through enhancing the transformations of NO to NO2. In the absence of NO, NH3 exhibited no inhibitive effect on Hg0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH3 and Hg0. In the presence of NO, although NH3 lowered Hg0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH3. This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg0 oxidation co-benefit from SCR units in coal-fired power plants.

  14. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    You, Fu-Tian [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China); Yu, Guang-Wei, E-mail: gwyu@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Wang, Yin, E-mail: yinwang@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Xing, Zhen-Jiao [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Liu, Xue-Jiao; Li, Jie [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China)

    2017-08-15

    Highlights: • Loading manganese oxides on activated carbon effectively promotes NO oxidation. • NO adsorption-desorption on activated carbon is fundamental to NO oxidation. • A high Mn{sup 4+}/Mn{sup 3+} ratio contributes to NO oxidation by promoting lattice O transfer. - Abstract: Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnO{sub x})-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N{sub 2} adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnO{sub x} and the test conditions on the reaction. MLAC with 7.5 wt.% MnO{sub x} (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O{sub 2}, room temperature and GHSV ca. 16000 h{sup −1}. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O{sub 2} concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnO{sub x} loading is assumed to be related to Mn{sup 4+}/Mn{sup 3+} ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnO{sub x} lattice O transfer is proposed.

  15. Catalytic steam gasification of biomass in fluidized bed at low temperature: Conversion from livestock manure compost to hydrogen-rich syngas

    International Nuclear Information System (INIS)

    Xiao, Xianbin; Le, Duc Dung; Li, Liuyun; Meng, Xianliang; Cao, Jingpei; Morishita, Kayoko; Takarada, Takayuki

    2010-01-01

    Utilizing large amounts of animal waste as a source of renewable energy has the potential to reduce its disposal problems and associated pollution issues. Gasification characteristics of the manure compost make it possible for low temperature gasification. In this paper, an energy efficient approach to hydrogen-rich syngas from manure compost is represented at relatively low temperature, around 600 o C, in a continuous-feeding fluidized bed reactor. The effects of catalyst performance, reactor temperature, steam, and reaction type on gas yield, gas composition, and carbon conversion efficiency are discussed. The Ni-Al 2 O 3 catalyst simultaneously promotes tar cracking and steam reforming. Higher temperature contributes to higher gas yield and carbon conversion. The steam introduction increases hydrogen yield, by steam reforming and water-gas shift reaction. Two-stage gasification is also tried, showing the advantage of better catalyst utilization and enhancing the catalytic reactions to some extent.

  16. Low Temperature Catalyst for NH3 Removal

    Science.gov (United States)

    Monje, Oscar; Melendez, Orlando

    2013-01-01

    Air revitalization technologies maintain a safe atmosphere inside spacecraft by the removal of C02, ammonia (NH3), and trace contaminants. NH3 onboard the International Space Station (ISS) is produced by crew metabolism, payloads, or during an accidental release of thermal control refrigerant. Currently, the ISS relies on removing NH3 via humidity condensate and the crew wears hooded respirators during emergencies. A different approach to cabin NH3 removal is to use selective catalytic oxidation (SCO), which builds on thermal catalytic oxidation concepts that could be incorporated into the existing TCCS process equipment architecture on ISS. A low temperature platinum-based catalyst (LTP-Catalyst) developed at KSC was used for converting NH3 to H20 and N2 gas by SCO. The challenge of implementing SCO is to reduce formation of undesirable byproducts like NOx (N20 and NO). Gas mixture analysis was conducted using FTIR spectrometry in the Regenerable VOC Control System (RVCS) Testbed. The RVCS was modified by adding a 66 L semi-sealed chamber, and a custom NH3 generator. The effect of temperature on NH3 removal using the LTP-Catalyst was examined. A suitable temperature was found where NH3 removal did not produce toxic NO, (NO, N02) and N20 formation was reduced.

  17. Co-Fe-Si Aerogel Catalytic Honeycombs for Low Temperature Ethanol Steam Reforming

    Directory of Open Access Journals (Sweden)

    Montserrat Domínguez

    2012-09-01

    Full Text Available Cobalt talc doped with iron (Fe/Co~0.1 and dispersed in SiO2 aerogel was prepared from silica alcogel impregnated with metal nitrates by supercritical drying. Catalytic honeycombs were prepared following the same procedure, with the alcogel synthesized directly over cordierite honeycomb pieces. The composite aerogel catalyst was characterized by X-ray diffraction, scanning electron microscopy, focus ion beam, specific surface area and X-ray photoelectron spectroscopy. The catalytic layer is about 8 µm thick and adheres well to the cordierite support. It is constituted of talc layers of about 1.5 µm × 300 nm × 50 nm which are well dispersed and anchored in a SiO2 aerogel matrix with excellent mass-transfer properties. The catalyst was tested in the ethanol steam reforming reaction, aimed at producing hydrogen for on-board, on-demand applications at moderate temperature (573–673 K and pressure (1–7 bar. Compared to non-promoted cobalt talc, the catalyst doped with iron produces less methane as byproduct, which can only be reformed at high temperature, thereby resulting in higher hydrogen yields. At 673 K and 2 bar, 1.04 NLH2·mLEtOH(l−1·min−1 are obtained at S/C = 3 and W/F = 390 g·min·molEtOH−1.

  18. Ammonia synthesis at low temperatures

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2000-01-01

    have been carried out to evaluate its feasibility. The calculations suggest that it might be possible to catalytically produce ammonia from molecular nitrogen at low temperatures and pressures, in particular if energy is fed into the process electrochemically. (C) 2000 American Institute of Physics.......Density functional theory (DFT) calculations of reaction paths and energies for the industrial and the biological catalytic ammonia synthesis processes are compared. The industrial catalyst is modeled by a ruthenium surface, while the active part of the enzyme is modeled by a MoFe6S9 complex...

  19. Catalytic properties of thermophilic lactate dehydrogenase and halophilic malate dehydrogenase at high temperature and low water activity.

    Science.gov (United States)

    Hecht, K; Wrba, A; Jaenicke, R

    1989-07-15

    Thermophilic lactate dehydrogenases from Thermotoga maritima and Bacillus stearothermophilus are stable up to temperature limits close to the optimum growth temperature of their parent organisms. Their catalytic properties are anomalous in that Km shows a drastic increase with increasing temperature. At low temperatures, the effect levels off. Extreme halophilic malate dehydrogenase from Halobacterium marismortui exhibits a similar anomaly. Increasing salt concentration (NaCl) leads to an optimum curve for Km, oxaloacctate while Km, NADH remains constant. Previous claims that the activity of halophilic malate dehydrogenase shows a maximum at 1.25 M NaCl are caused by limiting substrate concentration; at substrate saturation, specific activity of halophilic malate dehydrogenase reaches a constant value at ionic strengths I greater than or equal to 1 M. Non-halophilic (mitochondrial) malate dehydrogenase shows Km characteristics similar to those observed for the halophilic enzyme. The drastic decrease in specific activity of the mitochondrial enzyme at elevated salt concentrations is caused by the salt-induced increase in rigidity of the enzyme, rather than gross structural changes.

  20. Experiment and modeling of low-concentration methane catalytic combustion in a fluidized bed reactor

    International Nuclear Information System (INIS)

    Yang, Zhongqing; Yang, Peng; Zhang, Li; Guo, Mingnv; Ran, Jingyu

    2016-01-01

    Highlights: • The catalytic combustion of 0.15~3 vol. % low concentration methane in a fluidized bed was studied. • A mathematical model was proposed on the basis of gas–solid flow theory. • A comparative analysis of the established model with plug flow, mixed flow and K-L models was carried out. • The axial methane profile along fluidized bed was predicted by using the mathematical model. • The bed temperature has greater impact on methane conversion than fluidized velocity. - Abstract: This study undertakes a theoretical analysis and an experimental investigation into the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed reactor using 0.5 wt.% Pd/Al_2O_3 as catalytic particles. A mathematical model is established based on gas–solid flow theory and is used to study the effects of bed temperature and fluidized velocity on methane catalytic combustion, and predict the dimensionless methane concentration axial profile in reactor. It is shown that methane conversion increases with bed temperature, but decreases with increasing fluidized velocity. These theoretical results are found to correlate well with the experimental measurement, with a deviation within 5%. A comparative analysis of the developed model with plug flow, mixed flow and K-L models is also carried out, and this further verifies that the established model better reflects the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed. Using this reaction model, it was found that the difference in methane conversion between dense and freeboard zones gradually increases with bed temperature; the dense zone reaction levels off at 650 °C, thereby minimizing the difference between the dense and freeboard regions to around 15%. With an increase in bed temperature, the dimensionless methane concentration in the dense zone decreases exponentially, while in the splash zone, it varies from an exponential decay to a slow

  1. Solid strong base K-Pt/NaY zeolite nano-catalytic system for completed elimination of formaldehyde at room temperature

    Science.gov (United States)

    Song, Shaoqing; Wu, Xi; Lu, Changhai; Wen, Meicheng; Le, Zhanggao; Jiang, Shujuan

    2018-06-01

    Solid strong base nano-catalytic system of K-modification NaY zeolite supported 0.08% Pt (K-Pt/NaY) were constructed for eliminating HCHO at room temperature. In the catalytic process, activation energy over K-Pt/NaY nano-catalytic system was greatly decreased along with the enhanced reaction rate. Characterization and catalytic tests revealed the surface electron structure of K-Pt/NaY was improved, as reflected by the enhanced HCHO adsorption capability, high sbnd OH concentration, and low-temperature reducibility. Therefore, the optimal K-Pt/NaY showed high catalytic efficiency and strong H2O tolerance for HCHO elimination by directly promoting the reaction between active sbnd OH and formate species. These results may suggest a new way for probing the advanced solid strong base nano-catalytic system for the catalytic elimination of indoor HCHO.

  2. COMPARISON OF CATALYTIC ACTIVITIES BOTH FOR SELECTIVE OXIDATION AND DECOMPOSITION OF AMMONIA OVER Fe/HZβ CATALYST

    Directory of Open Access Journals (Sweden)

    YELİZ ÇETİN

    2016-11-01

    Full Text Available Ammonia is one of the syngas contaminants that must be removed before using the syngas downstream applications. The most promising hot-gas clean-up techniques of ammonia are selective catalytic oxidation (SCO and catalytic decomposition. In this study, the catalytic activities over Zeolite Hβ supported iron catalyst (Fe/HZβ were compared both for the two catalytic routes. For SCO experiments; temperature (300-550 °C, O2 (2000-6000 ppmv and (0-10% H2 concentrations were investigated with the presence of 800 ppm NH3 in each of the final gas mixture. In the second route, catalytic ammonia decomposition experiments were carried out with H2 in balance N2 (0-30% containing 800 ppm NH3 at 700°C and 800°C. In the SCO, NH3 conversions were increased with increasing reaction temperatures with the absence of H2 in the reaction mixture. With 10% H2, it was shown that NH3 conversions increased with decreasing the reaction temperature. This was interpreted as the competing H2 and NH3 oxidations over the catalyst. On the other hand, in the catalytic decomposition, thermodynamic equilibrium conversion of almost 100% was attained at both 700 and 800 °C. Upon H2 addition, all conversions decreased. The decrease in conversion seemed to be linear with inlet hydrogen concentration. Hydrogen was seen to inhibit ammonia decomposition reaction. It was shown that Fe/HZβ catalyst is better to use for catalytic decomposition of NH3 in syngas rather than SCO of NH3 in spite of higher reaction temperatures needed in the decomposition reaction.

  3. A Comparative Discussion of the Catalytic Activity and CO2-Selectivity of Cu-Zr and Pd-Zr (Intermetallic Compounds in Methanol Steam Reforming

    Directory of Open Access Journals (Sweden)

    Norbert Köpfle

    2017-02-01

    Full Text Available The activation and catalytic performance of two representative Zr-containing intermetallic systems, namely Cu-Zr and Pd-Zr, have been comparatively studied operando using methanol steam reforming (MSR as test reaction. Using an inverse surface science and bulk model catalyst approach, we monitored the transition of the initial metal/intermetallic compound structures into the eventual active and CO2-selective states upon contact to the methanol steam reforming mixture. For Cu-Zr, selected nominal stoichiometries ranging from Cu:Zr = 9:2 over 2:1 to 1:2 have been prepared by mixing the respective amounts of metallic Cu and Zr to yield different Cu-Zr bulk phases as initial catalyst structures. In addition, the methanol steam reforming performance of two Pd-Zr systems, that is, a bulk system with a nominal Pd:Zr = 2:1 stoichiometry and an inverse model system consisting of CVD-grown ZrOxHy layers on a polycrystalline Pd foil, has been comparatively assessed. While the CO2-selectivity and the overall catalytic performance of the Cu-Zr system is promising due to operando formation of a catalytically beneficial Cu-ZrO2 interface, the case for Pd-Zr is different. For both Pd-Zr systems, the low-temperature coking tendency, the high water-activation temperature and the CO2-selectivity spoiling inverse WGS reaction limit the use of the Pd-Zr systems for selective MSR applications, although alloying of Pd with Zr opens water activation channels to increase the CO2 selectivity.

  4. Selective growth of Ge nanowires by low-temperature thermal evaporation.

    Science.gov (United States)

    Sutter, Eli; Ozturk, Birol; Sutter, Peter

    2008-10-29

    High-quality single-crystalline Ge nanowires with electrical properties comparable to those of bulk Ge have been synthesized by vapor-liquid-solid growth using Au growth seeds on SiO(2)/Si(100) substrates and evaporation from solid Ge powder in a low-temperature process at crucible temperatures down to 700 °C. High nanowire growth rates at these low source temperatures have been identified as being due to sublimation of GeO from substantial amounts of GeO(2) on the powder. The Ge nanowire synthesis from GeO is highly selective at our substrate temperatures (420-500 °C), i.e., occurs only on Au vapor-liquid-solid growth seeds. For growth of nanowires of 10-20 µm length on Au particles, an upper bound of 0.5 nm Ge deposition was determined in areas of bare SiO(2)/Si substrate without Au nanoparticles.

  5. Low-temperature preparation of pyrolytic carbon

    International Nuclear Information System (INIS)

    Kidd, R.W.; Seifert, D.A.; Browning, M.F.

    1984-01-01

    Previous studies have demonstrated that nuclear waste forms coated with chemical vapor deposited pyrolytic carbon (PyC) at about 1273 K can provide ground water leach protection. To minimize the release during coating of volatile material from the waste forms and permit the coating of waste forms with a low softening point, a study was initiated to develop parameters for the catalytic deposition of PyC at low temperatures. The parameters surveyed in a fluidized-bed coater were deposition temperatures, carbon precursors, catalyst, diluent gas, concentration, and pressure

  6. Controlled synthesis of graphitic carbon-encapsulated α-Fe2O3 nanocomposite via low-temperature catalytic graphitization of biomass and its lithium storage property

    International Nuclear Information System (INIS)

    Wu, Feng; Huang, Rong; Mu, Daobin; Wu, Borong; Chen, Yongjian

    2016-01-01

    Highlights: • Facile synthesis of graphitic carbon/α-Fe 2 O 3 nano-sized anode composite. • In situ low temperature catalytic graphitization of biomass material. • Onion-like graphitic carbon layers conformally encapsulating around α-Fe 2 O 3 core. • High lithium storage properties, especially, outstanding cycle performance. - Abstract: A delicate structure of graphitic carbon-encapsulated α-Fe 2 O 3 nanocomposite is in situ constructed via “Absorption–Catalytic graphitization–Oxidation” strategy, taking use of biomass matter of degreasing cotton as carbon precursor and solution reservoir. With the assistance of the catalytic graphitization effect of iron core, onion-like graphitic carbon (GC) shell is made directly from the biomass at low temperature (650 °C). The nanosized α-Fe 2 O 3 particles would effectively mitigate volumetric strain and shorten Li + transport path during charge/discharge process. The graphitic carbon shells may promote charge transfer and protect active particles from directly exposing to electrolyte to maintain interfacial stability. As a result, the as-prepared α-Fe 2 O 3 @GC composite displays an outstanding cycle performance with a reversible capacity of 1070 mA h g −1 after 430 cycles at 0.2C, as well as a good rate capability of ∼ 950 mA h g −1 after 100 cycles at 1C and ∼ 850 mA h g −1 even up to 200 cycles at a 2C rate.

  7. Catalytic briquettes from low-rank coal for NO reduction

    Energy Technology Data Exchange (ETDEWEB)

    A. Boyano; M.E. Galvez; R. Moliner; M.J. Lazaro [Instituto de Carboquimica, CSIC, Zaragoza (Spain)

    2007-07-01

    The briquetting is one of the most ancient and widespread techniques of coal agglomeration which is nowadays becoming useless for combustion home applications. However, the social increasing interest in environmental protection opens new applications to this technique, especially in developed countries. In this work, a series of catalytic briquettes were prepared from low-rank Spanish coal and commercial pitch by means of a pressure agglomeration method. After that, they were cured in air and doped by equilibrium impregnation with vanadium compounds. Preparation conditions (especially those of activation and oxidizing process) were changed to study their effects on catalytic behaviour. Catalytic briquettes showed a relative high NO conversion at low temperatures in all cases, however, a strong relation between the preparation process and the reached NO conversion was observed. Preparation procedure has an effect not only on the NO reduction efficiency but also on the mechanical strength of the briquettes as a consequence of the structural and chemical changes carried out during the activation and oxidation procedures. Generally speaking mechanical resistance is enhanced by an optimal porous volume and the creation of new carboxyl groups on surface. Just on the contrary, NO reduction is promoted by high microporous structures and higher amounts of surface oxygen groups. Both facts force to find an optimum point in the preparation produce which will depend on the application. 24 refs., 4 figs., 3 tabs.

  8. Radio-Frequency-Based NH₃-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences.

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-07-12

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH₃ storage control, the influence of the storage degree on the catalyst performance, i.e., on NO x conversion and NH₃ slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH₃ storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  9. Characterization and Catalytic Activity of Mn-Co/TiO2 Catalysts for NO Oxidation to NO2 at Low Temperature

    Directory of Open Access Journals (Sweden)

    Lu Qiu

    2016-01-01

    Full Text Available A series of Mn-Co/TiO2 catalysts were prepared by wet impregnation method and evaluated for the oxidation of NO to NO2. The effects of Co amounts and calcination temperature on NO oxidation were investigated in detail. The catalytic oxidation ability in the temperature range of 403–473 K was obviously improved by doping cobalt into Mn/TiO2. These samples were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscope (TEM and hydrogen temperature programmed reduction (H2-TPR. The results indicated that the formation of dispersed Co3O4·CoMnO3 mixed oxides through synergistic interaction between Mn-O and Co-O was directly responsible for the enhanced activities towards NO oxidation at low temperatures. Doping of Co enhanced Mn4+ formation and increased chemical adsorbed oxygen amounts, which also accelerated NO oxidation.

  10. Amorphous saturated Cerium-Tungsten-Titanium oxide nanofibers catalysts for NOx selective catalytic reaction

    DEFF Research Database (Denmark)

    Dankeaw, Apiwat; Gualandris, Fabrizio; Silva, Rafael Hubert

    2018-01-01

    experiments at the best working conditions (dry and in absence of SO2) are performed to characterize the intrinsic catalytic behavior of the new catalysts. At temeprature lower than 300 °C, superior NOx conversion properties of the amorphous TiOx nanofibers over the crystallized TiO2 (anatase) nanofibers......Herein for the first time, Ce0.184W0.07Ti0.748O2-δ nanofibers are prepared by electrospinning to serve as catalyst in the selective catalytic reduction (SCR) process. The addition of cerium is proven to inhibit crystallization of TiO2, yielding an amorphous TiOx-based solid solution stable up...... temperatures (catalysts in a wide range...

  11. Selective catalytic reduction of nitric oxide with acetaldehyde over NaY zeolite catalyst in lean exhaust feed

    International Nuclear Information System (INIS)

    Schmieg, Steven J.; Cho, Byong K.; Oh, Se H.

    2004-01-01

    Steady-state selective catalytic reduction (SCR) of nitric oxide (NO) was investigated under simulated lean-burn conditions using acetaldehyde (CH 3 CHO) as the reductant. This work describes the influence of catalyst space velocity and the impact of nitric oxide, acetaldehyde, oxygen, sulfur dioxide, and water on NO x reduction activity over NaY zeolite catalyst. Results indicate that with sufficient catalyst volume 90% NO x conversion can be achieved at temperatures relevant to light-duty diesel exhaust (150-350C). Nitric oxide and acetaldehyde react to form N 2 , HCN, and CO 2 . Oxygen is necessary in the exhaust feed stream to oxidize NO to NO 2 over the catalyst prior to reduction, and water is required to prevent catalyst deactivation. Under conditions of excess acetaldehyde (C 1 :N>6:1) and low temperature ( x conversion is apparently very high; however, the NO x conversion steadily declines with time due to catalytic oxidation of some of the stored (adsorbed) NO to NO 2 , which can have a significant impact on steady-state NO x conversion. With 250ppm NO in the exhaust feed stream, maximum NO x conversion at 200C can be achieved with =400ppm of acetaldehyde, with higher acetaldehyde concentrations resulting in production of acetic acid and breakthrough of NO 2 causing lower NO x conversion levels. Less acetaldehyde is necessary at lower NO concentrations, while more acetaldehyde is required at higher temperatures. Sulfur in the exhaust feed stream as SO 2 can cause slow deactivation of the catalyst by poisoning the adsorption and subsequent reaction of nitric oxide and acetaldehyde, particularly at low temperature

  12. Filter bag De-NOx system with powder type catalysts at low temperature

    International Nuclear Information System (INIS)

    Kim, Byung-Hwan; Kim, Jeong-Heon; Kang, Pil-Sun; Yoo, Seung-Kwan; Yoon, Kyoon-Duk

    2010-01-01

    Combustion of carbon source materials (MSW, RDF, sludge, coal etc.) leads to the emission of harmful gaseous pollutants such as SO x , NO x , mercury, particulate matter, and dioxins etc. In particular, the emission of nitrogen oxides (NO x ) from the solid waste incinerator remains a serious air pollution problem. The previous research concerns have focused mainly on NO x reduction of stationary sources at high temperature SCR or SNCR process. Selective catalytic reduction (SCR) with NH 3 is the most widespread system used to control NO x emissions. However, this process suffers from several disadvantages due to the use of thermo fragile honeycomb type module and high temperature (about 300 degree Celsius) operation which consumes additional heating energy. To overcome this hurdle, filter bag De-NO x system with powder type catalysts at low temperature (less than 200 degree Celsius) has been under investigation in recent years and looks interesting because neither additional heat nor honeycomb type modules are required. Filter bag and powder type catalysts are cheap and effective materials to remove NO x at low temperature. In this study, the selective catalytic reduction of NO x was carried out on a filter support reactor with 300 mesh powder type catalysts at low temperature. The experiments were performed by powder type MnO x and V 2 O 5 / TiO 2 catalyst at low temperature ranging between 130 and 250 degree Celsius. Also, the effect of SO 2 and H 2 O on the NO conversion was investigated under our test conditions. The powder type catalysts were characterized by X-ray photoelectron spectrum (XPS) for measuring the state of oxygen on the catalyst surface and X-ray diffraction (XRD). It was observed that NO conversion of the powder type V 2 O 5 / TiO 2 catalyst was 85 % at 200 degree Celsius under presence of oxygen and that of MnO x was 50 % at the same condition. From these results, the powder type V 2 O 5 / TiO 2 catalyst showed an excellent performance on the

  13. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  14. Metathesis in the generation of low-temperature gas in marine shales

    Directory of Open Access Journals (Sweden)

    Jarvie Daniel M

    2010-01-01

    Full Text Available Abstract The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are either the same (generation under equilibrium control or closely associated. Here we report the catalytic interconversion of hydrocarbons (metathesis as the source of equilibrium in experiments with Cretaceous Mowry shale at 100°C. Focus was on two metathetic equilibria: methane, ethane, and propane, reported earlier, Q (K = [(C1*(C3]/[(C22], and between these hydrocarbons and n-butane, Q* (K = [(C1*(n-C4]/[(C2*(C3], reported here for the first time. Two observations stand out. Initial hydrocarbon products are near equilibrium and have maximum average molecular weights (AMW. Over time, products fall from equilibrium and AMW in concert. It is consistent with metathesis splitting olefin intermediates [Cn] to smaller intermediates (fission as gas generation creates open catalytic sites ([ ]: [Cn] + [ ] → [Cn-m] + [Cm]. Fission rates increasing exponentially with olefin molecular weight could contribute to these effects. AMW would fall over time, and selective fission of [C3] and [n-C4] would draw Q and Q* from equilibrium. The results support metathesis as the source of thermodynamic equilibrium in natural gas.

  15. Catalytic reduction of nitric oxide with ammonia over transition metal ion-exchanged Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Sciyama, T; Arakawa, T; Matsuda, T; Yamazoe, N; Takita, Y

    1975-01-01

    The catalytic reduction of nitric oxide with ammonia was studied over transition metal ion-exchanged Y zeolite (Me-Y) catalysts. The reaction products are nitrogen, nitrous oxide, and water in all cases. Selectivities to N/sub 2/ are 60 to 80% on all the cation exchanged zeolite catalysts exhibiting a relatively minor variation with the cationic species exchanged. The copper (II)-Y catalyst exhibits low temperature activity and has an unusual catalytic activity-temperature profile with a maximum at 120/sup 0/C. The catalytic activity is enhanced considerably when a second cation, especially cobalt (II) or iron (III) is coexchanged together with Cu (II) in Y zeolite.

  16. Emerging catalytic technologies related to the denoxing of waste gases from thermal power stations

    International Nuclear Information System (INIS)

    Busca, G.

    2002-01-01

    The emerging catalytic technologies related to the DeNOxing of waste gases from thermal power stations are briefly discussed. In the case of the Selective Catalytic Reduction of NO x with hydrocarbons new zeolite-based or metal oxide catalytic systems are under development, whose stability and performances approach more and more those needed for a commercial process. The processes for the low temperature Selective Catalytic Reduction of NO x with ammonia are apparently promising allowing a possible application in a tail-end process configuration, at least after a total abatement of SO x . The processes of combined abatement of NO x and dioxins are already applied industrially. Also the Selective Oxidation of ammonia slip to nitrogen is already proposed as commercial process. In both last cases, however, few information is available in the open literature [it

  17. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Directory of Open Access Journals (Sweden)

    Markus Dietrich

    2017-07-01

    Full Text Available The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13 was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  18. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-01-01

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. PMID:28704929

  19. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime....... On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes...... at 400ºC. The potential of using WO3 ceramic as an alternative anode materials has been explored. The relatively high electrode polarization resistance obtained, 11 Ohm cm2 at 600 ºC, proved the inadequate catalytic activity of this system for hydrogen oxidation. At the end of this thesis...

  20. Effect of Atomic Hydrogen on Preparation of Highly Moisture-Resistive SiNx Films at Low Substrate Temperatures

    Science.gov (United States)

    Heya, Akira; Niki, Toshikazu; Takano, Masahiro; Yonezawa, Yasuto; Minamikawa, Toshiharu; Muroi, Susumu; Minami, Shigehira; Izumi, Akira; Masuda, Atsushi; Umemoto, Hironobu; Matsumura, Hideki

    2004-12-01

    Highly moisture-resistive SiNx films on a Si substrate are obtained at substrate temperatures of 80°C by catalytic chemical vapor deposition (Cat-CVD) using a source gas with H2. Atomic hydrogen effected the selective etching of a weak-bond regions and an increase in atomic density induced by the energy of the surface reaction. It is concluded that Cat-CVD using H2 is a promising candidate for the fabrication of highly moisture-resistive SiNx films at low temperatures.

  1. Production of jet fuel range paraffins by low temperature polymerization of gaseous light olefins using ionic liquid

    International Nuclear Information System (INIS)

    Jiang, Peiwen; Wu, Xiaoping; Zhu, Lijuan; Jin, Feng; Liu, Junxu; Xia, Tongyan; Wang, Tiejun; Li, Quanxin

    2016-01-01

    Graphical abstract: A novel catalytic transformation of light olefins into jet fuel range iso-paraffins by the low-temperature olefin polymerizations under atmospheric conditions. - Highlights: • A novel transformation of light olefins to jet fuel range paraffins was demonstrated. • The synthetic fuels can be produced by atmospheric olefin polymerizations. • C 8 –C 15 iso-paraffins from light olefins was achieved with a selectivity of 80.6%. - Abstract: This work demonstrated a novel catalytic transformation of gaseous olefins into jet fuel range iso-paraffins by the low-temperature olefin polymerizations under atmospheric conditions. The production of the desired C 8 –C 15 iso-paraffins with the selectivity of 80.6 C mol% was achieved by the room-temperature polymerizations of gaseous light olefins using the [BMIM] Al 2 Cl 7 ionic liquid. The influences of the reaction conditions on the olefinic polymerizations were investigated in detail. The properties of hydrocarbons in the synthetic fuels were determined by the GC–MS analyses combined with 1 H NMR, and 13 C NMR analyses. The formation of C 8 –C 15 hydrocarbons from gaseous light olefins was illustrated by the identified products and the functional groups. This transformation potentially provides a useful avenue for the production of the most important components of iso-paraffins required in jet fuels.

  2. Differences in the catalytic mechanisms of mesophilic and thermophilic indole-3-glycerol phosphate synthase enzymes at their adaptive temperatures

    International Nuclear Information System (INIS)

    Zaccardi, Margot J.; Mannweiler, Olga; Boehr, David D.

    2012-01-01

    Highlights: ► Catalytic mechanisms of thermophilic–mesophilic enzymes may differ. ► Product release is rate-determining for thermophilic IGPS at low temperatures. ► But at higher temperatures, proton transfer from the general acid is rate-limiting. ► Rate-determining step is different still for mesophilic IGPS. ► Both chemical and physical steps of catalysis are important for temperature adaptation. -- Abstract: Thermophilic enzymes tend to be less catalytically-active at lower temperatures relative to their mesophilic counterparts, despite having very similar crystal structures. An often cited hypothesis for this general observation is that thermostable enzymes have evolved a more rigid tertiary structure in order to cope with their more extreme, natural environment, but they are also less flexible at lower temperatures, leading to their lower catalytic activity under mesophilic conditions. An alternative hypothesis, however, is that complementary thermophilic–mesophilic enzyme pairs simply operate through different evolutionary-optimized catalytic mechanisms. In this communication, we present evidence that while the steps of the catalytic mechanisms for mesophilic and thermophilic indole-3-glycerol phosphate synthase (IGPS) enzymes are fundamentally similar, the identity of the rate-determining step changes as a function of temperature. Our findings indicate that while product release is rate-determining at 25 °C for thermophilic IGPS, near its adaptive temperature (75 °C), a proton transfer event, involving a general acid, becomes rate-determining. The rate-determining steps for thermophilic and mesophilic IGPS enzymes are also different at their respective, adaptive temperatures with the mesophilic IGPS-catalyzed reaction being rate-limited before irreversible CO 2 release, and the thermophilic IGPS-catalyzed reaction being rate limited afterwards.

  3. Low-temperature plasma-catalytic oxidation of formaldehyde in atmospheric pressure gas streams

    International Nuclear Information System (INIS)

    Ding Huixian; Zhu Aimin; Lu Fugong; Xu Yong; Zhang Jing; Yang Xuefeng

    2006-01-01

    Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag/CeO 2 pellets at atmospheric pressure and 70 0 C. With a feed gas mixture of 276 ppm HCHO, 21.0% O 2 , 1.0% H 2 O in N 2 , ∼99% of formaldehyde can be effectively destructed with an 86% oxidative conversion into CO 2 at GHSV of 16500 h -1 and input discharge energy density of 108 J l -1 . At the same experimental conditions, the conversion percentages of HCHO to CO 2 from pure plasma-induced oxidation (discharges over fused silica pellets) and from pure catalytic oxidation over Ag/CeO 2 (without discharges) are 6% and 33% only. The above results and the CO plasma-catalytic oxidation experiments imply that the plasma-generated short-lived gas phase radicals, such as O and HO 2 , play important roles in the catalytic redox circles of Ag/CeO 2 to oxidize HCHO and CO to CO 2

  4. Selective catalytic reduction of NO{sub x} by olefins

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, F

    1997-12-31

    The removal of nitrogen oxides from the exhaust of lean-burn gasoline fuelled and diesel-fuelled engines, operating under net oxidizing conditions, has recently attracted considerable attention. In this work, three different catalytic systems (Al{sub 2}O{sub 3}, Cu/Al{sub 2}O{sub 3} and Cu/ZSM-5) are investigated for their suitability as catalysts for the selective reduction of nitrogen oxides by hydrocarbons in excess oxygen. Special emphasis is given to the formation of potentially harmful byproducts such as hydrogen cyanide (HCN), cyanic acid (HNCO), ammonia (NH{sub 3}) and nitrous oxide (N{sub 2}O). The effect of reaction temperature, nitrogen oxide (NO, NO{sub 2}), hydrocarbon (ethene, propene) and water on activity and the formation of byproducts is investigated. In situ FTIR spectroscopy and temperature-programmed surface reactions (TPSR) of absorbed species in different atmospheres were used to investigate the nature and reactivity of adsorbates formed under reaction conditions. The catalytic activity was strongly influenced by the presence of water in the feed. The effects of the other parameters were suppressed and the performance generally decreased, except when propene was used for the reduction of NO{sub x} over Cu/ZSM-5. Over Cu/ZSM-5 clearly higher conversion was obtained, when ethene was used as reducing agent, while there was no significant difference when starting from NO or NO{sub 2}. In contrast, with {gamma}-Al{sub 2}O{sub 3} NO{sub 2} was reduced more efficiently than NO with both reductants. The impregnation of {gamma}-Al{sub 2}O{sub 3} with copper led to an extensive loss of this performance. For dry feeds and with increasing CuO loading, the catalysts reached maximum activity at lower temperature and the maximum yield of nitrogen slightly decreased. (author) figs., tabs., refs.

  5. Room and low temperature synthesis of carbon nanofibres

    International Nuclear Information System (INIS)

    Boskovic, Bojan O.

    2002-01-01

    Carbon nanotubes and nanofibres have attracted attention in recent years as new materials with a number of very promising potential applications. Carbon nanotubes are potential candidates for field emitters in flat panel displays. Carbon nanofibres could also be used as a hydrogen storage material and as a filling material in polymer composites. Carbon nanotubes are already used as tips in scanning probe microscopy due to their remarkable mechanical and electrical properties, and could be soon used as nanotweezers. Use of carbon nanotubes in nanoelectronics will open further miniaturisation prospects. Temperatures ranging from 450 to 1000 deg C have been a required for catalytic growth of carbon nanotubes and nanofibres. Researchers have been trying to reduce the growth temperatures for decades. Low temperature growth conditions will allow the growth of carbon nanotubes on different substrates, such glass (below 650 deg C) and as plastics (below 150 deg C) over relatively large areas, which is especially suitable for fiat panel display applications. Room temperature growth conditions could open up the possibility of using different organic substrates and bio-substrates for carbon nanotubes synthesis. Carbon nanofibres have been synthesised at room temperature and low temperatures below 250 deg C using radio frequency plasma enhanced chemical vapour deposition (r.f. PECVD). Previously, the growth of carbon nanofibres has been via catalytic decomposition of hydrocarbons or carbon monoxide at temperatures above 300 deg C. To the best of our knowledge, this is the first evidence of the growth of carbon nanofibres at temperatures lower than 300 deg C by any method. The use of a transition metal catalyst and r.f.-PECVD system is required for the growth of the carbon nanofibre when a hydrocarbon flows above the catalyst. Within the semiconductor industry r.f.-PECVD is a well established technique which lends itself for the growth of carbon nanofibres for various

  6. Hydrogen cyanide formation in selective catalytic reduction of nitrogen oxides over Cu/ZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, F; Koeppel, R; Baiker, A [Department of Chemical Engineering and Industrial Chemistry, Swiss Federal Institute of Technology, Zurich, (Switzerland)

    1994-01-06

    Hydrogen cyanide is formed over Cu/ZSM-5 during the selective catalytic reduction of NO[sub x] by either propylene or ethylene in the temperature range 450-600 K. Under the reaction conditions used (reactant feed: 973 ppm NO, 907 ppm propene or 1448 ppm ethylene, 2% oxygen, W/F=0.1 g s cm[sup -3]), the concentration of hydrogen cyanide reaches 20, respectively, 30 ppm, depending on whether ethylene or propene are used as hydrocarbons. In addition, significant N[sub 2]O formation is observed at temperatures lower than 700 K, independent of the hydrocarbon used

  7. Low-temperature synthesis of allyl dimethylamine by selective heating under microwave irradiation used for water treatment

    International Nuclear Information System (INIS)

    Tian Binghui; Luan Zhaokun; Li Mingming

    2005-01-01

    Low-temperature synthesis of allyl dimethylamine (ADA) by selective heating under microwave irradiation (MI) used for water treatment is investigated. The effect of MI, ultrasound irradiation (UI) and conventional heating on yield of ADA, reaction time and the flocculation efficiency of polydiallyl dimethylammunion chloride (PDADMAC) prepared form ADA were studied. The results show that by selective heating at low temperature, MI not only increases yield of ADA and reduces reaction time, but also greatly enhances the flocculation efficiency of PDADMAC

  8. INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

    Science.gov (United States)

    The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

  9. Catalysis of metal-clay intercalation compound in the low temperature coal hydrogasification

    Energy Technology Data Exchange (ETDEWEB)

    Fuda, Kiyoshi; Kimura, Mitsuhiko; Miyamoto, Norimitsu; Matsunaga, Toshiaki

    1986-10-23

    Focusing the hydrogenating methanation by gaseous phase catalytic reactions of low temperature volatile components, the catalytic effects of Ni metal and the effects of carriers having sensitive effects on the catalytic activities of Ni metal were studied. Sample coals were prepared from Shin-Yubari coal, and Ni hydride-montmorillonite complex catalysts and the catalysts produced by carring Ni nitrate on alumina and burning in hydrogen gas flows were prepared. The hydrogasification were carried out in a reaction tube. As a result, the montmorillonite-Ni compounds catalysts had high catalitic effects and high conversion ratio of 90% or more in the low temperature coal gasification. The catalitic effects of carried Ni metal strongly depended on the carrier substances, and the rank of effects for the carriers was montmorillonite>zeorite>TiO/sub 2/>alpha-Al/sub 2/O/sub 3/>MgO>SiO/sub 2/=gamma-Al/sub 2/O/sub 3/. (3 figs, 3 tabs, 3 refs)

  10. Development of a catalytically assisted combustor for a gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Yasushi; Fujii, Tomoharu; Sato, Mikio [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-01 (Japan); Kanazawa, Takaaki; Inoue, Hitoshi [Kansai Electric Power Company, Inc., 3-11-20 Nakoji, Amagasaki, Hyoho 661 (Japan)

    1999-01-01

    A catalytically assisted low NO{sub x} combustor has been developed which has the advantage of catalyst durability. This combustor is composed of a burner section and a premixed combustion section behind the burner section. The burner system consists of six catalytic combustor segments and six premixing nozzles, which are arranged alternately and in parallel. Fuel flow rate for the catalysts and the premixing nozzles are controlled independently. The catalytic combustion temperature is maintained under 1000C, additional premixed gas is injected from the premixing nozzles into the catalytic combustion gas, and lean premixed combustion at 1300C is carried out in the premixed combustion section. This system was designed to avoid catalytic deactivation at high temperature and thermal or mechanical shock fracture of the honeycomb monolith. In order to maintain the catalyst temperature under 1000C, the combustion characteristics of catalysts at high pressure were investigated using a bench scale reactor and an improved catalyst was selected for the combustor test. A combustor for a 20MW class multi-can type gas turbine was designed and tested under high pressure conditions using LNG fuel. Measurements of NO{sub x}, CO and unburned hydrocarbon were made and other measurements were made to evaluate combustor performance under various combustion temperatures and pressures. As a result of the tests, it was proved that NO{sub x} emission was lower than 10ppm converted at 16% O{sub 2}, combustion efficiency was almost 100% at 1300C of combustor outlet temperature and 13.5ata of combustor inlet pressure

  11. Catalytic selective reduction of NO with ethylene over a series of copper catalysts on amorphous silicas

    International Nuclear Information System (INIS)

    Carniti, P.; Gervasini, A.; Modica, V.H.; Ravasio, N.

    2000-01-01

    Catalytic selective reduction of NO to N 2 was studied comparing a series of Cu-based catalysts (ca. 8wt.%) supported over amorphous pure and modified silicas: SiO 2 , SiO 2 -Al 2 O 3 , SiO 2 -TiO 2 , SiO 2 -ZrO 2 . The catalysts were prepared by the chemisorption-hydrolysis method which ensured the formation of a unique copper phase well dispersed over all supports, as confirmed by scanning electron micrographs (SEMs). Temperature-programmed reduction (TPR) analyses confirmed the presence of dispersed copper species which underwent complete reduction at a temperature of about 220C, independently of the support. It was found that the support affects the extent of NO reduction as well as the selectivity to N 2 formation. Maximum N 2 yield was found in the range 275-300C. The catalyst prepared over SiO 2 -Al 2 O 3 was the most active and selective with respect to the other silicas. Competitiveness factors (c.f.'s) as high as 13-20% in the temperature range 200-250C could be calculated. For all catalysts, the temperature of the N 2 peak maximum did not correspond to that of the maximum C 2 H 4 oxidation to CO 2 , suggesting the presence of two different sites for the oxidation and the reduction activity. On the catalyst prepared on SiO 2 -Al 2 O 3 , a kinetic interpretation of catalytic data collected at different contact times and temperatures permitted evaluating the ratio between kinetic coefficients as well as the difference between activation energies of NO reduction by C 2 H 4 and C 2 H 4 oxidation by O 2

  12. Fuel Flexible, Low Emission Catalytic Combustor for Opportunity Fuel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Eteman, Shahrokh

    2013-06-30

    Limited fuel resources, increasing energy demand and stringent emission regulations are drivers to evaluate process off-gases or process waste streams as fuels for power generation. Often these process waste streams have low energy content and/or highly reactive components. Operability of low energy content fuels in gas turbines leads to issues such as unstable and incomplete combustion. On the other hand, fuels containing higher-order hydrocarbons lead to flashback and auto-ignition issues. Due to above reasons, these fuels cannot be used directly without modifications or efficiency penalties in gas turbine engines. To enable the use of these wide variety of fuels in gas turbine engines a rich catalytic lean burn (RCL®) combustion system was developed and tested in a subscale high pressure (10 atm.) rig. The RCL® injector provided stability and extended turndown to low Btu fuels due to catalytic pre-reaction. Previous work has shown promise with fuels such as blast furnace gas (BFG) with LHV of 85 Btu/ft3 successfully combusted. This program extends on this work by further modifying the combustor to achieve greater catalytic stability enhancement. Fuels containing low energy content such as weak natural gas with a Lower Heating Value (LHV) of 6.5 MJ/m3 (180 Btu/ft3 to natural gas fuels containing higher hydrocarbon (e.g ethane) with LHV of 37.6 MJ/m3 (1010 Btu/ft3) were demonstrated with improved combustion stability; an extended turndown (defined as the difference between catalytic and non-catalytic lean blow out) of greater than 250oF was achieved with CO and NOx emissions lower than 5 ppm corrected to 15% O2. In addition, for highly reactive fuels the catalytic region preferentially pre-reacted the higher order hydrocarbons with no events of flashback or auto-ignition allowing a stable and safe operation with low NOx and CO emissions.

  13. High-Temperature Compatible Nickel Silicide Thermometer And Heater For Catalytic Chemical Microreactors

    DEFF Research Database (Denmark)

    Jensen, Søren; Quaade, U.J.; Hansen, Ole

    2005-01-01

    Integration of heaters and thermometers is important for agile and accurate control and measurement of the thermal reaction conditions in microfabricated chemical reactors (microreactors). This paper describes development and operation of nickel silicide heaters and temperature sensors...... for temperatures exceeding 700 °C. The heaters and thermometers are integrated with chemical microreactors for heterogeneous catalytic conversion of gasses, and thermally activated catalytic conversion of CO to CO2 in the reactors is demonstrated. The heaters and thermometers are shown to be compatible...

  14. An Overview of Recent Advances of the Catalytic Selective Oxidation of Ethane to Oxygenates

    Directory of Open Access Journals (Sweden)

    Robert D. Armstrong

    2016-05-01

    Full Text Available The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals. Unfortunately, low C–H bond reactivity and kinetically labile products are just some reasons affecting the development and commercialisation of such processes. Research into direct ethane oxidation is therefore disparate, with approaches ranging from oxidation in the gas phase at high temperatures to enzyme catalysed hydroxylation under ambient conditions. Furthermore, in overcoming the barrier posed by the chemically inert C–H bond a range of oxidants have been utilised. Despite years of research, this remains an intriguing topic from both academic and commercial perspectives. Herein we describe some recent developments within the field of catalytic ethane oxidation focusing on the formation of oxygenated products, whilst addressing the key challenges which are still to be overcome.

  15. Activation of surface lattice oxygen in single-atom Pt/CeO 2 for low-temperature CO oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Lei; Mei, Donghai; Xiong, Haifeng; Peng, Bo; Ren, Zhibo; Pereira Hernandez, Xavier I.; DelaRiva, Andrew; Wang, Meng; Engelhard, Mark H.; Kovarik, Libor; Datye, Abhaya K.; Wang, Yong

    2017-12-14

    While single-atom catalysts can provide high catalytic activity and selectivity, application in industrial catalysts demands long term performance and the ability to regenerate the catalysts. We have investigated the factors that lead to improved catalytic activity of a Pt/CeO2 catalyst for low temperature CO oxidation. Single-atom Pt/CeO2 becomes active for CO oxidation under lean condition only at elevated temperatures, because CO is strongly bound to ionic Pt sites. Reducing the catalyst, even under mild conditions, leads to onset of CO oxidation activity even at room temperature. This high activity state involves the transformation of mononuclear Pt species to sub-nanometer sized Pt particles. Under oxidizing conditions, the Pt can be restored to its stable, single-atom state. The key to facile regeneration is the ability to create mobile Pt species and suitable trapping sites on the support, making this a prototypical catalyst system for industrial application of single-atom catalysis.

  16. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  17. Promoted V2O5/TiO2 catalysts for selective catalytic reduction of NO with NH3 at low temperatures

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Schill, Leonhard; Godiksen, Anita

    2016-01-01

    characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR, Raman, FTIR and EPR spectroscopy to investigate the properties of the catalysts. XRPD, Raman and FTIR showed that promotion with 15 wt.% HPA does not cause V2O5 to be present in crystalline form, also at a loading of 5 wt.% V2O5. Hence, use of HPAs does......The influence of varying the V2O5 content (3–6 wt.%) was studied for the selective catalytic reduction (SCR) of nitrogen oxides by ammonia on heteropoly acid (HPA)- and tungsten oxide (WO3)-promoted V2O5/TiO2 catalysts. The SCR activity and alkali deactivation resistance of HPA-promoted V2O5/TiO2...... catalysts was found to be much higher than for WO3-promoted catalysts. By increasing the vanadium content from 3 to 5 wt.% the catalysts displayed a two fold increase in activity at 225 °C and retained their initial activity after alkali doping at a molar K/V ratio of 0.181. Furthermore, the catalysts were...

  18. Thermodynamic characteristics of a low concentration methane catalytic combustion gas turbine

    International Nuclear Information System (INIS)

    Yin, Juan; Su, Shi; Yu, Xin Xiang; Weng, Yiwu

    2010-01-01

    Low concentration methane, emitted from coal mines, landfill, animal waste, etc. into the atmosphere, is not only a greenhouse gas, but also a waste energy source if not utilised. Methane is 23 times more potent than CO 2 in terms of trapping heat in the atmosphere over a timeframe of 100 years. This paper studies a novel lean burn catalytic combustion gas turbine, which can be powered with about 1% methane (volume) in air. When this technology is successfully developed, it can be used not only to mitigate the methane for greenhouse gas reduction, but also to utilise such methane as a clean energy source. This paper presents our study results on the thermodynamic characteristics of this new lean burn catalytic combustion gas turbine system by conducting thermal performance analysis of the turbine cycle. The thermodynamic data including thermal efficiencies and exergy loss of main components of the turbine system are presented under different pressure ratios, turbine inlet temperatures and methane concentrations.

  19. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.

    2005-01-01

    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  20. Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx

    International Nuclear Information System (INIS)

    Sarah C. Larson; Vicki H. Grassian

    2006-01-01

    Nanocrystalline zeolites with discrete crystal sizes of less than 100 nm have different properties relative to zeolites with larger crystal sizes. Nanocrystalline zeolites have improved mass transfer properties and very large internal and external surface areas that can be exploited for many different applications. The additional external surface active sites and the improved mass transfer properties of nanocrystalline zeolites offer significant advantages for selective catalytic reduction (SCR) catalysis with ammonia as a reductant in coal-fired power plants relative to current zeolite based SCR catalysts. Nanocrystalline NaY was synthesized with a crystal size of 15-20 nm and was thoroughly characterized using x-ray diffraction, electron paramagnetic resonance spectroscopy, nitrogen adsorption isotherms and Fourier Transform Infrared (FT-IR) spectroscopy. Copper ions were exchanged into nanocrystalline NaY to increase the catalytic activity. The reactions of nitrogen dioxides (NO x ) and ammonia (NH 3 ) on nanocrystalline NaY and CuY were investigated using FT-IR spectroscopy. Significant conversion of NO 2 was observed at room temperature in the presence of NH 3 as monitored by FT-IR spectroscopy. Copper-exchanged nanocrystalline NaY was more active for NO 2 reduction with NH 3 relative to nanocrystalline NaY

  1. Efficient catalytic combustion in integrated micropellistors

    International Nuclear Information System (INIS)

    Bársony, I; Ádám, M; Fürjes, P; Dücső, Cs; Lucklum, R; Hirschfelder, M; Kulinyi, S

    2009-01-01

    This paper analyses two of the key issues of the development of catalytic combustion-type sensors: the selection and production of active catalytic particles on the micropellistor surface as well as the realization of a reliable thermal conduction between heater element and catalytic surface, for the sensing of temperature increase produced by the combustion. The report also demonstrates that chemical sensor product development by a MEMS process is a continuous struggle for elimination of all uncertainties influencing reliability and sensitivity of the final product

  2. Low temperature conversion of plastic waste into light hydrocarbons

    International Nuclear Information System (INIS)

    Shah, Sajid Hussain; Khan, Zahid Mahmood; Raja, Iftikhar Ahmad; Mahmood, Qaisar; Bhatti, Zulfiqar Ahmad; Khan, Jamil; Farooq, Ather; Rashid, Naim; Wu, Donglei

    2010-01-01

    Advance recycling through pyrolytic technology has the potential of being applied to the management of plastic waste (PW). For this purpose 1 l volume, energy efficient batch reactor was manufactured locally and tested for pyrolysis of waste plastic. The feedstock for reactor was 50 g waste polyethylene. The average yield of the pyrolytic oil, wax, pyrogas and char from pyrolysis of PW were 48.6, 40.7, 10.1 and 0.6%, respectively, at 275 deg. C with non-catalytic process. Using catalyst the average yields of pyrolytic oil, pyrogas, wax and residue (char) of 50 g of PW was 47.98, 35.43, 16.09 and 0.50%, respectively, at operating temperature of 250 deg. C. The designed reactor could work at low temperature in the absence of a catalyst to obtain similar products as for a catalytic process.

  3. Reduction and Analysis of Low Temperature Shift Heterogeneous Catalyst for Water Gas Reaction in Ammonia Production

    Directory of Open Access Journals (Sweden)

    Zečević, N.

    2013-09-01

    Full Text Available In order to obtain additional quantities of hydrogen after the reforming reactions of natural gas and protect the ammonia synthesis catalyst, it is crucial to achieve and maintain maximum possible activity, selectivity and stability of the low temperature shift catalyst for conversion of water gas reaction during its lifetime. Whereas the heterogeneous catalyst comes in oxidized form, it is of the utmost importance to conduct the reduction procedure properly. The proper reduction procedure and continuous analysis of its performance would ensure the required activity, selectivity and stability throughout the catalyst’s service time. For the proper reduction procedure ofthe low temperature shift catalyst, in addition to process equipment, also necessary is a reliable and realistic system for temperature measurements, which will be effective for monitoring the exothermal temperature curves through all catalyst bed layers. For efficiency evaluation of low shift temperature catalyst reduction and its optimization, it is necessary to determine at regular time intervals the temperature approach to equilibrium and temperature profiles of individual layers by means of "S" and "die off" temperature exothermal curves. Based on the obtained data, the optimum inlet temperature could be determined, in order to maximally extend the service life of the heterogeneous catalyst as much as possible, and achieve the optimum equilibrium for conversion of the water gas. This paper presents the methodology for in situ reduction of the low temperature shift heterogeneous catalyst and the developed system for monitoring its individual layers to achieve the minimum possible content of carbon monoxide at the exit of the reactor. The developed system for temperature monitoring through heterogeneous catalyst layers provides the proper procedure for reduction and adjustment of optimum process working conditions for the catalyst by the continuous increase of reactor inlet

  4. The selective catalytic reduction of NO with NH3 over a novel Ce-Sn-Ti mixed oxides catalyst: Promotional effect of SnO2

    Science.gov (United States)

    Yu, Ming'e.; Li, Caiting; Zeng, Guangming; Zhou, Yang; Zhang, Xunan; Xie, Yin'e.

    2015-07-01

    A series of novel catalysts (CexSny) for the selective catalytic reduction of NO by NH3 were prepared by the inverse co-precipitation method. The aim of this novel design was to improve the NO removal efficiency of CeTi by the introduction of SnO2. It was found that the Ce-Sn-Ti catalyst was much more active than Ce-Ti and the best Ce:Sn molar ratio was 2:1. Ce2Sn1 possessed a satisfied NO removal efficiency at low temperature (160-280 °C), while over 90% NO removal efficiency maintained in the temperature range of 280-400 °C at the gas hourly space velocity (GHSV) of 50,000 h-1. Besides, Ce2Sn1 kept a stable NO removal efficiency within a wide range of GHSV and a long period of reacting time. Meanwhile, Ce2Sn1 exhibited remarkable resistance to both respectively and simultaneously H2O and SO2 poisoning due to the introduction of SnO2. The promotional effect of SnO2 was studied by N2 adsorption-desorption, X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR) for detail information. The characterization results revealed that the excellent catalytic performance of Ce2Sn1 was associated with the higher specific surface area, larger pore volume and poorer crystallization. Besides, the introduction of SnO2 could result in not only greater conversion of Ce4+ to Ce3+ but also the increase amount of chemisorbed oxygen, which are beneficial to improve the SCR activity. More importantly, a novel peak appearing at lower temperatures through the new redox equilibrium of 2Ce4+ + Sn2+ ↔ 2Ce3+ + Sn4+ and higher total H2 consumption can be obtained by the addition of SnO2. Finally, the possible reaction mechanism of the selective catalytic reduction over Ce2Sn1 was also proposed.

  5. Efficient decomposition of formaldehyde at room temperature over Pt/honeycomb ceramics with ultra-low Pt content.

    Science.gov (United States)

    Nie, Longhui; Zheng, Yingqiu; Yu, Jiaguo

    2014-09-14

    Pt/honeycomb ceramic (Pt/HC) catalysts with ultra-low Pt content (0.005-0.055 wt%) were for the first time prepared by an impregnation of honeycomb ceramics with Pt precursor and NaBH4-reduction combined method. The microstructures, morphologies and textural properties of the resulting samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The obtained Pt/HC catalysts were used for catalytic oxidative decomposition of formaldehyde (HCHO) at room temperature. It was found that the as-prepared Pt/HC catalysts can efficiently decompose HCHO in air into CO2 and H2O at room temperature. The catalytic activity of the Pt/HC catalysts increases with increasing the Pt loading in the range of 0.005-0.013 wt%, and the further increase of the Pt loading does not obviously improve catalytic activity. From the viewpoint of cost and catalytic performance, 0.013 wt% Pt loading is the optimal Pt loading amount, and the Pt/HC catalyst with 0.013 wt% Pt loading also exhibited good catalytic stability. Considering practical applications, this work will provide new insights into the low-cost and large-scale fabrication of advanced catalytic materials for indoor air purification.

  6. Ethanol-selective catalytic reduction of NO by Ag/Al2O3 catalysts: Activity and deactivation by alkali salts

    DEFF Research Database (Denmark)

    Schill, Leonhard; Putluru, Siva Sankar Reddy; Jacobsen, Casper Funk

    2012-01-01

    Ag/Al2O3 catalysts with and without potassium doping were prepared by incipient wetness impregnation and characterized by N2 physisorption, XRPD, NH3-TPD and SEM. The influence of the Ag content from 1 to 5 wt.% was investigated for the selective catalytic reduction (SCR) of NO with ethanol. The 3...... wt.% Ag/Al2O3 catalyst was found to be the most active and CO2 selective over a wide temperature window (300–500 ◦C). Addition of 500 ppm of H2 has a mild promotional effect on the activity while SO2 has a strong negative influence on the SCR activity. Furthermore, the Ag/Al2O3 ethanol-SCR catalyst......3 ethanol-SCR catalyst compared to the conventional NH3-SCR catalyst. The still low potassium resistance, in combination with the high sensitivity to SO2, seems not to make these catalysts a real option for biomass fired boilers....

  7. Selective and low temperature transition metal intercalation in layered tellurides

    Science.gov (United States)

    Yajima, Takeshi; Koshiko, Masaki; Zhang, Yaoqing; Oguchi, Tamio; Yu, Wen; Kato, Daichi; Kobayashi, Yoji; Orikasa, Yuki; Yamamoto, Takafumi; Uchimoto, Yoshiharu; Green, Mark A.; Kageyama, Hiroshi

    2016-01-01

    Layered materials embrace rich intercalation reactions to accommodate high concentrations of foreign species within their structures, and find many applications spanning from energy storage, ion exchange to secondary batteries. Light alkali metals are generally most easily intercalated due to their light mass, high charge/volume ratio and in many cases strong reducing properties. An evolving area of materials chemistry, however, is to capture metals selectively, which is of technological and environmental significance but rather unexplored. Here we show that the layered telluride T2PTe2 (T=Ti, Zr) displays exclusive insertion of transition metals (for example, Cd, Zn) as opposed to alkali cations, with tetrahedral coordination preference to tellurium. Interestingly, the intercalation reactions proceed in solid state and at surprisingly low temperatures (for example, 80 °C for cadmium in Ti2PTe2). The current method of controlling selectivity provides opportunities in the search for new materials for various applications that used to be possible only in a liquid. PMID:27966540

  8. Component Development to Accelerate Commercial Implementation of Ultra-Low Emissions Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    McCarty, Jon; Berry, Brian; Lundberg, Kare; Anson, Orris

    2003-03-31

    This final report describes a 2000-2003 program for the development of components and processes to enhance the commercialization of ultra-low emissions catalytic combustion in industrial gas turbines. The range of project tasks includes: development of more durable, lower-cost catalysts and catalytic combustor components; development and design of a catalytic pre-burner and a catalytic pilot burner for gas turbines, and on-site fuel conversion processing for utilization of liquid fuel.

  9. A Dynamic Supramolecular System Exhibiting Substrate Selectivity in the Catalytic Epoxidation of Olefins

    DEFF Research Database (Denmark)

    Jonsson, Stefan; Odille, Fabrice G. J.; Norrby, Per-Ola

    2005-01-01

    A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction.......A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction....

  10. System and method for selective catalytic reduction of nitrogen oxides in combustion exhaust gases

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A

    2014-04-08

    A multi-stage selective catalytic reduction (SCR) unit (32) provides efficient reduction of NOx and other pollutants from about 50-550.degree. C. in a power plant (19). Hydrogen (24) and ammonia (29) are variably supplied to the SCR unit depending on temperature. An upstream portion (34) of the SCR unit catalyzes NOx+NH.sub.3 reactions above about 200.degree. C. A downstream portion (36) catalyzes NOx+H.sub.2 reactions below about 260.degree. C., and catalyzes oxidation of NH.sub.3, CO, and VOCs with oxygen in the exhaust above about 200.degree. C., efficiently removing NOx and other pollutants over a range of conditions with low slippage of NH.sub.3. An ammonia synthesis unit (28) may be connected to the SCR unit to provide NH.sub.3 as needed, avoiding transport and storage of ammonia or urea at the site. A carbonaceous gasification plant (18) on site may supply hydrogen and nitrogen to the ammonia synthesis unit, and hydrogen to the SCR unit.

  11. Selective Catalytic Reduction (SCR) for mobile application - heavy duty diesel; Selektive Katalytische Reduktion (SCR) fuer die mobile Anwendung - LKW

    Energy Technology Data Exchange (ETDEWEB)

    Huennekes, E.; Neubauer, T. [Engelhard Technologies GmbH, Hannover (Germany); Roth, S.A.; Patchett, J.A. [Engelhard Corp., R and D, Iselin, NJ (United States)

    2006-07-01

    Different system configurations of particulate and NOx control via selective catalytic reduction (SCR) were discussed. Advantages and disadvantages were described and the final choice of the optimum system will strongly depend on the application, the market (US, EU) and the system costs. Especially when considering low temperature NOx control, the optimum adjustment of the NO{sub 2}/NO{sub x} ratio in front of an SCR system plays an important role. When generating NO2 over an oxidation catalyst, the resulting NO{sub 2}/NO{sub x} ratio strongly depends on temperature and space velocity. Steady state data show an optimum NO{sub 2}/NO{sub x} ratio between 35 and 60% at temperatures about 240 C. Three DOC systems in front of an SCR system were investigated with the purpose to generate high, low and optimum NO{sub 2}/NO{sub x} ratios. The fast SCR reaction at 1:1 NO: NO2 with NH{sub 3} is the preferred reaction pathway until either NO or NO{sub 2} are consumed. The benefit of an optimum designed DOC system can be seen in the transient response after a sudden increase in urea dosing. The time for the optimum designed system to reach maximum NO{sub x} conversion is much shorter compared with systems having excess NO or NO{sub 2} Ammonia oxidation catalysts (AMOX) are effective means in controlling ammonia from SCR systems. To be effective, AMOX must have selectivity to nitrogen over N{sub 2}O and NO{sub x}. (orig.)

  12. HYBRID SELECTIVE NON-CATALYTIC REDUCTION (SNCR)/SELECTIVE CATALYTIC REDUCTION (SCR) DEMONSTRATION FOR THE REMOVAL OF NOx FROM BOILER FLUE GASES

    Energy Technology Data Exchange (ETDEWEB)

    Jerry B. Urbas

    1999-05-01

    The U. S. Department of Energy (DOE), Electric Power Research Institute (EPRI), Pennsylvania Electric Energy Research Council, (PEERC), New York State Electric and Gas and GPU Generation, Inc. jointly funded a demonstration to determine the capabilities for Hybrid SNCR/SCR (Selective Non-Catalytic Reduction/Selective Catalytic Reduction) technology. The demonstration site was GPU Generation's Seward Unit No.5 (147MW) located in Seward Pennsylvania. The demonstration began in October of 1997 and ended in December 1998. DOE funding was provided through Grant No. DE-FG22-96PC96256 with T. J. Feeley as the Project Manager. EPRI funding was provided through agreements TC4599-001-26999 and TC4599-002-26999 with E. Hughes as the Project Manager. This project demonstrated the operation of the Hybrid SNCR/SCR NO{sub x} control process on a full-scale coal fired utility boiler. The hybrid technology was expected to provide a cost-effective method of reducing NO{sub x} while balancing capital and operation costs. An existing urea based SNCR system was modified with an expanded-duct catalyst to provide increased NO{sub x} reduction efficiency from the SNCR while producing increased ammonia slip levels to the catalyst. The catalyst was sized to reduce the ammonia slip to the air heaters to less than 2 ppm while providing equivalent NO{sub x} reductions. The project goals were to demonstrate hybrid technology is capable of achieving at least a 55% reduction in NO{sub x} emissions while maintaining less than 2ppm ammonia slip to the air heaters, maintain flyash marketability, verify the cost benefit and applicability of Hybrid post combustion technology, and reduce forced outages due to ammonium bisulfate (ABS) fouling of the air heaters. Early system limitations, due to gas temperature stratification, restricted the Hybrid NO{sub x} reduction capabilities to 48% with an ammonia slip of 6.1 mg/Nm{sup 3} (8 ppm) at the catalyst inlet. After resolving the stratification

  13. Catalytic pyrolysis of hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Vail' eva, N A; Buyanov, R A

    1979-01-01

    Catalytic pyrolysis of petroleum fractions (undecane) was performed with the object of clarifying such questions as the mechanism of action of the catalyst, the concepts of activity and selectivity of the catalyst, the role of transport processes, the temperature ranges and limitations of the catalytic process, the effect of the catalyst on secondary processes, and others. Catalysts such as quartz, MgO, Al/sub 2/O/sub 3/, were used. Analysis of the experimental findings and the fact that the distribution of products is independent of the nature of the surface, demonstrate that the pyrolysis of hydrocarbons in the presence of catalysts is based on the heterogeneous-homogeneous radical-chain mechanism of action, and that the role of the catalysts reduces to increasing the concentration of free radicals. The concept of selectivity cannot be applied to catalysts here, since they do not affect the mechanism of the unfolding of the process of pyrolysis and their role consists solely in initiating the process. In catalytic pyrolysis the concepts of kinetic and diffusive domains of unfolding of the catalytic reaction do not apply, and only the outer surface of the catalyst is engaged, whereas the inner surface merely promotes deletorious secondary processes reducing the selectivity of the process and the activity of the catalyst. 6 references, 2 figures.

  14. Low-Energy, Low-Cost Production of Ethylene by Low- Temperature Oxidative Coupling of Methane

    Energy Technology Data Exchange (ETDEWEB)

    Radaelli, Guido [Siluria Technologies, Inc., San Francisco, CA (United States); Chachra, Gaurav [Siluria Technologies, Inc., San Francisco, CA (United States); Jonnavittula, Divya [Siluria Technologies, Inc., San Francisco, CA (United States)

    2017-12-30

    In this project, we develop a catalytic process technology for distributed small-scale production of ethylene by oxidative coupling of methane at low temperatures using an advanced catalyst. The Low Temperature Oxidative Coupling of Methane (LT-OCM) catalyst system is enabled by a novel chemical catalyst and process pioneered by Siluria, at private expense, over the last six years. Herein, we develop the LT-OCM catalyst system for distributed small-scale production of ethylene by identifying and addressing necessary process schemes, unit operations and process parameters that limit the economic viability and mass penetration of this technology to manufacture ethylene at small-scales. The output of this program is process concepts for small-scale LT-OCM catalyst based ethylene production, lab-scale verification of the novel unit operations adopted in the proposed concept, and an analysis to validate the feasibility of the proposed concepts.

  15. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J; Koljonen, T [VTT Energy, Espoo (Finland)

    1997-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  16. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  17. Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells.

    Science.gov (United States)

    García, Gonzalo; Koper, Marc T M

    2011-08-01

    Herein the general concepts of fuel cells are discussed, with special attention to low temperature fuel cells working in alkaline media. Alkaline low temperature fuel cells could well be one of the energy sources in the next future. This technology has the potential to provide power to portable devices, transportation and stationary sectors. With the aim to solve the principal catalytic problems at the anode of low temperature fuel cells, a fundamental study of the mechanism and kinetics of carbon monoxide as well as water dissociation on stepped platinum surfaces in alkaline medium is discussed and compared with those in acidic media. Furthermore, cations involved as promoters for catalytic surface reactions are also considered. Therefore, the aim of the present work is not only to provide the new fundamental advances in the electrocatalysis field, but also to understand the reactions occurring at fuel cell catalysts, which may help to improve the fabrication of novel electrodes in order to enhance the performance and to decrease the cost of low temperature fuel cells. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Selective catalytic oxidation of hydrocarbons as a challenge to the chemical engineer

    Energy Technology Data Exchange (ETDEWEB)

    Emig, G [Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Inst. fuer Technische Chemie 1

    1977-11-01

    In the conversion of the most important chemical raw materials, natural oil and natural gas, to intermediate or end products, selective catalytic oxidation plays an increasing role. This method makes it possible in many cases to use more economical, single-step processes instead of the older multi-step processes. Using the typical example of propylene oxidation or ammonoxidation, the problems encountered by chemical engineers in the development of a heterogeneous-catalytic method of oxidation are demonstrated. The importance of systematic catalyst development is stressed. General aspects of the development of novel processes or the improvement of existing catalytic processes are discussed.

  19. Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes

    Science.gov (United States)

    Ahuja, Ritu; Punji, Benudhar; Findlater, Michael; Supplee, Carolyn; Schinski, William; Brookhart, Maurice; Goldman, Alan S.

    2011-02-01

    Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products—that is, secondary alkyl arenes—with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts—specifically ‘pincer’-ligated iridium complexes—and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.

  20. High selectivity and stability of Mg-doped Al-MCM-41 for in-situ catalytic upgrading fast pyrolysis bio-oil

    International Nuclear Information System (INIS)

    Karnjanakom, Surachai; Suriya-umporn, Thanyamai; Bayu, Asep; Kongparakul, Suwadee; Samart, Chanatip; Fushimi, Chihiro; Abudula, Abuliti; Guan, Guoqing

    2017-01-01

    Highlights: • Mg-doped Al-MCM-41 was developed for in-situ catalytic upgrading of bio-oils. • Mg/Al-MCM-41 exhibited high selectivity to aromatic hydrocarbons. • The ratio of produced hydrocarbon reached up to 80% in upgraded bio-oil. • 1 wt.% Mg/Al-MCM-41 showed the highest catalytic activity. • Mg/Al-MCM-41 had stable reusability due to its coking inhabitation ability. - Abstract: In-situ catalytic upgrading of bio-oils derived from the fast pyrolysis of cellulose, lignin or sunflower stalk over Mg-doped Al-MCM-41 was investigated in details. It is found that Mg species with doping amounts ranged between 0.25 and 10 wt.% was well dispersed on Al-MCM-41, and that doping Mg on Al-MCM-41 effectively adjusted the acidity and basicity of the catalysts, resulting in significant improvement of bio-oil quality. Mg/Al-MCM-41 exhibited high selective conversion of bio-oils derived from cellulose, lignin or sunflower stalk to high value-added aromatic hydrocarbons via catalytic cracking, deoxygenation and aromatization. In the upgraded bio-oil, the relative total hydrocarbon amount reached up to approximately ≥80%, which consisted of aromatic hydrocarbon approximately 76% and aliphatic hydrocarbon approximately 4% for all feedstocks. The selectivity to the monocyclic aromatic hydrocarbons (MAHs) such as benzene, toluene and xylenes (BTXs) increased while the coke formed on the catalyst decreased with the increase in Mg doping amount. 1 wt.% Mg/Al-MCM-41 resulted in the highest relative total hydrocarbon amount in the upgraded bio-oil at lower catalytic deoxygenation temperature, and showed stable reusability for at least 5 cycles. It is expected that Mg/Al-MCM-41 can be widely applied for bio-oil upgrading in a practical process.

  1. A new experimental setup for high-pressure catalytic activity measurements on surface deposited mass-selected Pt clusters

    International Nuclear Information System (INIS)

    Watanabe, Yoshihide; Isomura, Noritake

    2009-01-01

    A new experimental setup to study catalytic and electronic properties of size-selected clusters on metal oxide substrates from the viewpoint of cluster-support interaction and to formulate a method for the development of heterogeneous catalysts such as automotive exhaust catalysts has been developed. The apparatus consists of a size-selected cluster source, a photoemission spectrometer, a scanning tunneling microscope (STM), and a high-pressure reaction cell. The high-pressure reaction cell measurements provided information on catalytic properties in conditions close to practical use. The authors investigated size-selected platinum clusters deposited on a TiO 2 (110) surface using a reaction cell and STM. Catalytic activity measurements showed that the catalytic activities have a cluster-size dependency.

  2. Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis

    Directory of Open Access Journals (Sweden)

    Byambasuren O

    2017-02-01

    Full Text Available The monometallic cobalt-based catalysts were prepared by pretreating the catalysts derived from carbonyl cluster precursor (CO6Co2CC(COOH2 supported on γ-Al2O3 with hydrogen at 180, 220, and 260°C respectively. The temperature effect of the pretreatments on the structure evolution of cluster precursors and the catalytic performance of the Fischer-Tropsch (F-T synthesis was investigated. The pretreated catalyst at 220°C with unique phase structure exhibited best catalytic activity and selectivity among three pretreated catalysts. Moreover, the catalysts exhibited high dispersion due to the formation of hydrogen bonds between the cluster precursor and γ-Al2O3 support.

  3. Multi-stage selective catalytic reduction of NOx in lean burn engine exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Penetrante, B.M.; Hsaio, M.C.; Merritt, B.T.; Vogtlin, G.E. [Lawrence Livermore National Lab., CA (United States)

    1997-12-31

    Many studies suggest that the conversion of NO to NO{sub 2} is an important intermediate step in the selective catalytic reduction (SCR) of NO{sub x} to N{sub 2}. Some effort has been devoted to separating the oxidative and reductive functions of the catalyst in a multi-stage system. This method works fine for systems that require hydrocarbon addition. The hydrocarbon has to be injected between the NO oxidation catalyst and the NO{sub 2} reduction catalyst; otherwise, the first-stage oxidation catalyst will also oxidize the hydrocarbon and decrease its effectiveness as a reductant. The multi-stage catalytic scheme is appropriate for diesel engine exhausts since they contain insufficient hydrocarbons for SCR, and the hydrocarbons can be added at the desired location. For lean-burn gasoline engine exhausts, the hydrocarbons already present in the exhausts will make it necessary to find an oxidation catalyst that can oxidize NO to NO{sub 2} but not oxidize the hydrocarbon. A plasma can also be used to oxidize NO to NO{sub 2}. Plasma oxidation has several advantages over catalytic oxidation. Plasma-assisted catalysis can work well for both diesel engine and lean-burn gasoline engine exhausts. This is because the plasma can oxidize NO in the presence of hydrocarbons without degrading the effectiveness of the hydrocarbon as a reductant for SCR. In the plasma, the hydrocarbon enhances the oxidation of NO, minimizes the electrical energy requirement, and prevents the oxidation of SO{sub 2}. This paper discusses the use of multi-stage systems for selective catalytic reduction of NO{sub x}. The multi-stage catalytic scheme is compared to the plasma-assisted catalytic scheme.

  4. Oscillatory behaviour of catalytic properties, structure and temperature during the catalytic partial oxidation of methane on Pd/Al2O3

    DEFF Research Database (Denmark)

    Kimmerle, B.; Baiker, A.; Grunwaldt, Jan-Dierk

    2010-01-01

    Pd/Al2O3 catalysts showed an oscillatory behaviour during the catalytic partial oxidation (CPO) of methane, which was investigated simultaneously by IR-thermography, X-ray absorption spectroscopy, and online mass-spectrometry to correlate the temperature, state of the catalyst and catalytic...... to self-reduction leading to extinction of the process. The latter was the key driver for the oscillations and thus gave additional insight into the mechanism of partial methane oxidation....

  5. HYBRID SELECTIVE NON-CATALYTIC REDUCTION (SNCR)/SELECTIVE CATALYTIC REDUCTION (SCR) DEMONSTRATION FOR THE REMOVAL OF NOx FROM BOILER FLUE GASES; FINAL

    International Nuclear Information System (INIS)

    Jerry B. Urbas

    1999-01-01

    The U. S. Department of Energy (DOE), Electric Power Research Institute (EPRI), Pennsylvania Electric Energy Research Council, (PEERC), New York State Electric and Gas and GPU Generation, Inc. jointly funded a demonstration to determine the capabilities for Hybrid SNCR/SCR (Selective Non-Catalytic Reduction/Selective Catalytic Reduction) technology. The demonstration site was GPU Generation's Seward Unit No.5 (147MW) located in Seward Pennsylvania. The demonstration began in October of 1997 and ended in December 1998. DOE funding was provided through Grant No. DE-FG22-96PC96256 with T. J. Feeley as the Project Manager. EPRI funding was provided through agreements TC4599-001-26999 and TC4599-002-26999 with E. Hughes as the Project Manager. This project demonstrated the operation of the Hybrid SNCR/SCR NO(sub x) control process on a full-scale coal fired utility boiler. The hybrid technology was expected to provide a cost-effective method of reducing NO(sub x) while balancing capital and operation costs. An existing urea based SNCR system was modified with an expanded-duct catalyst to provide increased NO(sub x) reduction efficiency from the SNCR while producing increased ammonia slip levels to the catalyst. The catalyst was sized to reduce the ammonia slip to the air heaters to less than 2 ppm while providing equivalent NO(sub x) reductions. The project goals were to demonstrate hybrid technology is capable of achieving at least a 55% reduction in NO(sub x) emissions while maintaining less than 2ppm ammonia slip to the air heaters, maintain flyash marketability, verify the cost benefit and applicability of Hybrid post combustion technology, and reduce forced outages due to ammonium bisulfate (ABS) fouling of the air heaters. Early system limitations, due to gas temperature stratification, restricted the Hybrid NO(sub x) reduction capabilities to 48% with an ammonia slip of 6.1 mg/Nm(sup 3) (8 ppm) at the catalyst inlet. After resolving the stratification problem

  6. N- versus C-domain selectivity of catalytic inactivation of human angiotensin converting enzyme by lisinopril-coupled transition metal chelates.

    Science.gov (United States)

    Hocharoen, Lalintip; Joyner, Jeff C; Cowan, J A

    2013-12-27

    The N- and C-terminal domains of human somatic angiotensin I converting enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates was tested for both reversible binding and irreversible catalytic inactivation of each domain of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and catalytic factors (double-filter effect).

  7. Combined effects Na and SO{sub 2} in flue gas on Mn-Ce/TiO{sub 2} catalyst for low temperature selective catalytic reduction of NO by NH{sub 3} simulated by Na{sub 2}SO{sub 4} doping

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Aiyi [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China); Yu, Danqing [School of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081 (China); Yang, Liu [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China); Sheng, Zhongyi, E-mail: 09377@njnu.edu.cn [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China)

    2016-08-15

    Highlights: • Sodium sulfate (Na{sub 2}SO{sub 4}) was deposited on Mn-Ce/TiO{sub 2} catalyst to simulate the co-existing of sodium and SO{sub 2} in the flue gas. • Na{sub 2}SO{sub 4} had strong and fluctuant influence on Mn-Ce/TiO{sub 2} catalyst’s performance in SCR of NOx with NH{sub 3}, due to the combined effect of the deactivation of sodium salts and the enhanced performance of ceria with surface sulfation. • The changes of the surface chemical species and acid sites on the Na{sub 2}SO{sub 4} deposited catalysts could be considered as the main reasons for the fluctuation changes with the catalytic activity. - Abstract: A series of Mn-Ce/TiO{sub 2} catalysts were synthesized through an impregnation method and used for low temperature selective catalytic reduction (SCR) of NOx with ammonia (NH{sub 3}). Na{sub 2}SO{sub 4} was added into the catalyst to simulate the combined effects of alkali metal and SO{sub 2} in the flue gas. Experimental results showed that Na{sub 2}SO{sub 4} had strong and fluctuant influence on the activity of Mn-Ce/TiO{sub 2}, because the effect of Na{sub 2}SO{sub 4} included pore occlusion and sulfation effect simultaneously. When Na{sub 2}SO{sub 4} loading content increased from 0 to 1 wt.%, the SCR activities of Na{sub 2}SO{sub 4}-doped catalysts decreased greatly. With further increasing amount of Na{sub 2}SO{sub 4}, however, the catalytic activity increased gradually. XRD results showed that Na{sub 2}SO{sub 4} doping could induce the crystallization of MnOx phases, which were also confirmed by TEM and SEM results. BET results showed that the surface areas decreased and a new bimodal mesoporous structure formed gradually with the increasing amount of Na{sub 2}SO{sub 4}. XPS results indicated that part of Ce{sup 4+} and Mn{sup 3+} were transferred to Ce{sup 3+} and Mn{sup 4+} due to the sulfation after Na{sub 2}SO{sub 4} deposition on the surface of the catalysts. When the doped amounts of Na{sub 2}SO{sub 4} increased, NH{sub 3

  8. Improvement of Toluene Selectivity via the Application of an Ethanol Oxidizing Catalytic Cell Upstream of a YSZ-Based Sensor for Air Monitoring Applications

    Science.gov (United States)

    Sato, Tomoaki; Breedon, Michael; Miura, Norio

    2012-01-01

    The sensing characteristics of a yttria-stabilized zirconia (YSZ)-based sensor utilizing a NiO sensing-electrode (SE) towards toluene (C7H8) and interfering gases (C3H6, H2, CO, NO2 and C2H5OH) were evaluated with a view to selective C7H8 monitoring in indoor atmospheres. The fabricated YSZ-based sensor showed preferential responses toward 480 ppb C2H5OH, rather than the target 50 ppb C7H8 at an operational temperature of 450 °C under humid conditions (RH ≃ 32%). To overcome this limitation, the catalytic activity of Cr2O3, SnO2, Fe2O3 and NiO powders were evaluated for their selective ethanol oxidation ability. Among these oxides, SnO2 was found to selectively oxidize C2H5OH, thus improving C7H8 selectivity. An inline pre-catalytic cell loaded with SnO2 powder was installed upstream of the YSZ-based sensor utilizing NiO-SE, which enabled the following excellent abilities by selectively catalyzing common interfering gases; sensitive ppb level detection of C7H8 lower than the established Japanese Guideline value; low interferences from 50 ppb C3H6, 500 ppb H2, 100 ppb CO, 40 ppb NO2, as well as 480 ppb C2H5OH. These operational characteristics are all indicative that the developed sensor may be suitable for real-time C7H8 concentration monitoring in indoor environments. PMID:22666053

  9. Selective oxidation

    International Nuclear Information System (INIS)

    Cortes Henao, Luis F.; Castro F, Carlos A.

    2000-01-01

    It is presented a revision and discussion about the characteristics and factors that relate activity and selectivity in the catalytic and not catalytic partial oxidation of methane and the effect of variables as the temperature, pressure and others in the methane conversion to methanol. It thinks about the zeolites use modified for the catalytic oxidation of natural gas

  10. Low-temperature SCR of NO with NH{sub 3} over activated semi-coke composite-supported rare earth oxides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinping; Yan, Zheng; Liu, Lili; Zhang, Yingyi; Zhang, Zuotai; Wang, Xidong, E-mail: xidong@pku.edu.cn

    2014-08-01

    The catalysts with different rare earth oxides (La, Ce, Pr and Nd) loaded onto activated semi-coke (ASC) via hydrothermal method are prepared for the selective catalytic reduction (SCR) of NO with NH{sub 3} at low temperature (150–300 °C). It is evidenced that CeO{sub 2} loaded catalysts present the best performance, and the optimum loading amount of CeO{sub 2} is about 10 wt%. Composite catalysts by doping La, Pr and Nd into CeO{sub 2} are prepared to obtain further improved catalytic properties. The SCR mechanism is investigated through various characterizations, including XRD, Raman, XPS and FT-IR, the results of which indicate that the oxygen defect plays an important role in SCR process and the doped rare earth elements effectively serve as promoters to increase the concentration of oxygen vacancies. It is also found that the oxygen vacancies in high concentration are favored for the adsorption of O{sub 2} and further oxidation of NO, which facilitates a rapid progressing of the following reduction reactions. The SCR process of NO with NH{sub 3} at low temperature over the catalysts of ASC composite-supported rare earth oxides mainly follows the Langmuir–Hinshlwood mechanism.

  11. Gold Supported on Graphene Oxide: An Active and Selective Catalyst for Phenylacetylene Hydrogenations at Low Temperatures

    DEFF Research Database (Denmark)

    Shao, Lidong; Huang, Xing; Teschner, Detre

    2014-01-01

    A constraint to industrial implementation of gold-catalyzed alkyne hydrogenation is that the catalytic activity was always inferior to those of other noble metals. In this work, gold was supported on graphene oxide (Au/GO) and used in a hydrogenation application. A 99% selectivity toward styrene...

  12. Alkali resistivity of Cu based selective catalytic reduction catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Jensen, Anker Degn; Riisager, Anders

    2012-01-01

    The deactivation of V2O5–WO3–TiO2, Cu–HZSM5 and Cu–HMOR plate type monolithic catalysts was investigated when exposed to KCl aerosols in a bench-scale reactor. Fresh and exposed catalysts were characterized by selective catalytic reduction (SCR) activity measurements, scanning electron microscope......–energy dispersive X-ray spectroscopy (SEM–EDX) and NH3-temperature programmed desorption (NH3-TPD). 95% deactivation was observed for the V2O5–WO3–TiO2 catalyst, while the Cu–HZSM5 and Cu–HMOR catalysts deactivated only 58% and 48%, respectively, after 1200 h KCl exposure. SEM analysis of the KCl aerosol exposed...... catalysts revealed that the potassium salt not only deposited on the catalyst surface, but also penetrated into the catalyst wall. Thus, the K/M ratio (M = V or Cu) was high on V2O5–WO3–TiO2 catalyst and comparatively less on Cu–HZSM5 and Cu–HMOR catalysts. NH3-TPD revealed that the KCl exposed Cu–HZSM5...

  13. Nanocrystalline Mn-Mo-Ce Oxide Anode Doped Rare Earth Ce and Its Selective Electro-catalytic Performance

    Directory of Open Access Journals (Sweden)

    SHI Yan-hua

    2017-09-01

    Full Text Available The anode oxide of nanocrystalline Mn-Mo-Ce was prepared by anode electro-deposition technology, and its nanostructure and selective electro-catalytic performance were investigated using the SEM, EDS, XRD, HRTEM, electrochemical technology and oxygen evolution efficiency testing. Furthermore, the selective electro-catalytic mechanism of oxygen evolution and chlorine depression was discussed. The results show that the mesh-like nanostructure Mn-Mo-Ce oxide anode with little cerium doped is obtained, and the oxygen evolution efficiency for the anode in the seawater is 99.51%, which means a high efficiency for the selective electro-catalytic for the oxygen evolution. Due to the structural characteristics of γ-MnO2, the OH- ion is preferentially absorbed, while Cl- absorption is depressed. OH- accomplishes the oxygen evolution process during the valence transition electrocatalysis of Mn4+/Mn3+, completing the selective electro-catalysis process. Ce doping greatly increases the reaction activity, and promotes the absorption and discharge; the rising interplanar spacing between active (100 crystalline plane promotes OH- motion and the escape of newborn O2, so that the selective electro-catalytic property with high efficient oxygen evolution and chlorine depression is achieved from the nano morphology effect.

  14. A recyclable Au(I) catalyst for selective homocoupling of arylboronic acids: significant enhancement of nano-surface binding for stability and catalytic activity.

    Science.gov (United States)

    Zhang, Xin; Zhao, Haitao; Wang, Jianhui

    2010-08-01

    Au nanoparticles stabilized by polystyrene-co-polymethacrylic acid microspheres (PS-co-PMAA) were prepared and characterized via X-ray diffraction (XRD), and transmission electron microscope (TEM). The Au nanoparticles supported on the microspheres showed highly selective catalytic activity for homo-coupling reactions of arylboronic acids in a system of aryl-halides and arylboronic acids. X-ray photoelectron spectroscopy (XPS) spectra of the catalyst shows large amounts of Au(I) complexes band to the surface of the Au nanoparticles, which contributes to the selective homocoupling of the arylboronic acids. More importantly, this supported Au complex is a highly recyclable catalyst. The supported Au catalyst can be recycled and reused at least 6 times for a phenylboronic acid reactant, whereas the parent complex shows very low catalytic activity for this compound. The high catalytic activity of this material is attributed to: (1) the high surface to volume ratio which leads to more active sites being exposed to reactants; (2) the strong surface binding of the Au nanoparticle to the Au(I) complexes, which enhances both the stability and the catalytic activity of these complexes.

  15. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1995-06-01

    This project has investigated new metal oxide catalysts for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as CO. Significant progress in catalyst development has been made during the course of the project. We have found that fluorite oxides, CeO{sub 2} and ZrO{sub 2}, and rare earth zirconates such as Gd{sub 2}Zr{sub 2}O{sub 7} are active and stable catalysts for reduction Of SO{sub 2} by CO. More than 95% sulfur yield was achieved at reaction temperatures about 450{degrees}C or higher with the feed gas of stoichiometric composition. Reaction of SO{sub 2} and CO over these catalysts demonstrated a strong correlation of catalytic activity with the catalyst oxygen mobility. Furthermore, the catalytic activity and resistance to H{sub 2}O and CO{sub 2} poisoning of these catalysts were significantly enhanced by adding small amounts of transition metals, such as Co, Ni, Co, etc. The resulting transition metal-fluorite oxide composite catalyst has superior activity and stability, and shows promise in long use for the development of a greatly simplified single-step sulfur recovery process to treat variable and dilute SO{sub 2} concentration gas streams. Among various active composite catalyst systems the Cu-CeO{sub 2} system has been extensively studied. XRD, XPS, and STEM analyses of the used Cu-CeO{sub 2} catalyst found that the fluorite crystal structure of ceria was stable at the present reaction conditions, small amounts of copper was dispersed and stabilized on the ceria matrix, and excess copper oxide particles formed copper sulfide crystals of little contribution to catalytic activity. A working catalyst consisted of partially sulfated cerium oxide surface and partially sulfided copper clusters. The overall reaction kinetics were approximately represented by a first order equation.

  16. Remarkable promoting effect of rhodium on the catalytic performance of Ag/Al2O3 for the selective reduction of NO with decane

    International Nuclear Information System (INIS)

    Sato, Kazuhito; Yoshinari, Tomohiro; Kintaichi, Yoshiaki; Haneda, Masaaki; Hamada, Hideaki

    2003-01-01

    The addition of small amounts of rhodium enhanced the activity of Ag/Al 2 O 3 catalyst for the selective reduction of NO with decane at low temperatures. The Rh-promoted Ag/Al 2 O 3 showed its high performance even in the presence of low concentrations of SO 2 . Based on the catalytic activity for elementary reactions, it was suggested that the role of added rhodium is to enhance the reaction between NO x and decane-derived species, leading to NO reduction. Catalyst characterization by UV-Vis spectroscopy indicated that the major silver species on Rh-promoted Ag/Al 2 O 3 is Ag nn δ+ clusters, which would be responsible for the high activity. FT-IR measurements revealed that the formation rate of isocyanate species, which is a major reaction intermediate, is higher on Rh-promoted Ag/Al 2 O 3

  17. Selective catalytic oxidation of hydrocarbons as a challenge to the chemical engineer

    Energy Technology Data Exchange (ETDEWEB)

    Emig, G [Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Lehrstuhl fuer Technische Chemie 1

    1978-08-01

    Selective catalytic oxidation is beginning to play a more and more significant role in the process of converting the most important chemical raw materials, crude oil and natural gas, into intermediate and end products. In many cases, this technique makes it possible to replace old processes consisting of many steps by more economical single-step reactions. The typical example of oxidation or ammoxidation of propylene demonstrates the problems which must be solved by the chemical engineer during the development of a heterogeneous catalytic oxidation process. The particular importance of a systematic development of a catalyst is emphasized. General aspects relating to the design of new catalytic processes, or the improvement of existing ones are also discussed.

  18. Catalytic methods using molecular oxygen for treatment of PMMS and ECLSS waste streams, volume 2

    Science.gov (United States)

    Akse, James R.

    1992-01-01

    Catalytic oxidation has proven to be an effective addition to the baseline sorption, ion exchange water reclamation technology which will be used on Space Station Freedom (SSF). Low molecular weight, polar organics such as alcohols, aldehydes, ketones, amides, and thiocarbamides which are poorly removed by the baseline multifiltration (MF) technology can be oxidized to carbon dioxide at low temperature (121 C). The catalytic oxidation process by itself can reduce the Total Organic Carbon (TOC) to below 500 ppb for solutions designed to model these waste waters. Individual challenges by selected contaminants have shown only moderate selectivity towards particular organic species. The combined technology is applicable to the more complex waste water generated in the Process Materials Management System (PMMS) and Environmental Control and Life Support System (ECLSS) aboard SSF. During the phase 3 Core Module Integrated Facility (CMIF) water recovery tests at NASA MSFC, real hygiene waste water and humidity condensate were processed to meet potable specifications by the combined technology. A kinetic study of catalytic oxidation demonstrates that the Langmuir-Hinshelwood rate equation for heterogeneous catalysts accurately represent the kinetic behavior. From this relationship, activation energy and rate constants for acetone were determined.

  19. Oxidation of mercury across selective catalytic reduction catalysts in coal-fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Constance L. Senior [Reaction Engineering International, Salt Lake City, UT (United States)

    2006-01-15

    A kinetic model for predicting the amount of mercury (Hg) oxidation across selective catalytic reduction (SCR) systems in coal-fired power plants was developed and tested. The model incorporated the effects of diffusion within the porous SCR catalyst and the competition between ammonia and Hg for active sites on the catalyst. Laboratory data on Hg oxidation in simulated flue gas and slipstream data on Hg oxidation in flue gas from power plants were modeled. The model provided good fits to the data for eight different catalysts, both plate and monolith, across a temperature range of 280-420{sup o}C, with space velocities varying from 1900 to 5000 hr{sup -1}. Space velocity, temperature, hydrochloric acid content of the flue gas, ratio of ammonia to nitric oxide, and catalyst design all affected Hg oxidation across the SCR catalyst. The model can be used to predict the impact of coal properties, catalyst design, and operating conditions on Hg oxidation across SCRs. 20 refs., 9 figs., 2 tabs.

  20. Catalytic applications of bio-inspired nanomaterials

    Science.gov (United States)

    Pacardo, Dennis Kien Balaong

    The biomimetic synthesis of Pd nanoparticles was presented using the Pd4 peptide, TSNAVHPTLRHL, isolated from combinatorial phage display library. Using this approach, nearly monodisperse and spherical Pd nanoparticles were generated with an average diameter of 1.9 +/- 0.4 nm. The peptide-based nanocatalyst were employed in the Stille coupling reaction under energy-efficient and environmentally friendly reaction conditions of aqueous solvent, room temperature and very low catalyst loading. To this end, the Pd nanocatalyst generated high turnover frequency (TOF) value and quantitative yields using ≥ 0.005 mol% Pd as well as catalytic activities with different aryl halides containing electron-withdrawing and electron-donating groups. The Pd4-capped Pd nanoparticles followed the atom-leaching mechanism and were found to be selective with respect to substrate identity. On the other hand, the naturally-occurring R5 peptide (SSKKSGSYSGSKGSKRRIL) was employed in the synthesis of biotemplated Pd nanomaterials which showed morphological changes as a function of Pd:peptide ratio. TOF analysis for hydrogenation of olefinic alcohols showed similar catalytic activity regardless of nanomorphology. Determination of catalytic properties of these bio-inspired nanomaterials are important as they serve as model system for alternative green catalyst with applications in industrially important transformations.

  1. Heterogeneous kinetic modeling of the catalytic conversion of cycloparaffins

    Science.gov (United States)

    Al-Sabawi, Mustafa N.

    The limited availability of high value light hydrocarbon feedstocks along with the rise in crude prices has resulted in the international recognition of the vast potential of Canada's oil sands. With the recent expansion of Canadian bitumen production come, however, many technical challenges, one of which is the significant presence of aromatics and cycloparaffins in bitumen-derived feedstocks. In addition to their negative environmental impact, aromatics limit fluid catalytic cracking (FCC) feedstock conversion, decrease the yield and quality of valuable products such as gasoline and middle distillates, increase levels of polyaromatic hydrocarbons prone to form coke on the catalyst, and ultimately compromise the FCC unit performance. Although cycloparaffins do not have such negative impacts, they are precursors of aromatics as they frequently undergo hydrogen transfer reactions. However, cycloparaffin cracking chemistry involves other competing reactions that are complex and need much investigation. This dissertation provides insights and understanding of the fundamentals of the catalytic cracking of cycloparaffins using carefully selected model compounds such as methylcyclohexane (MCH) and decalin. Thermal and catalytic cracking of these cycloparaffins on FCC-type catalysts are carried out using the CREC Riser Simulator under operating conditions similar to those of the industrial FCC units in terms of temperature, reaction time, reactant partial pressure and catalyst-to-hydrocarbon ratio. The crystallite size of the supported zeolites is varied between 0.4 and 0.9 microns, with both activity and selectivity being monitored. Catalytic conversions ranged between 4 to 16 wt% for MCH and between 8 to 27 wt% for decalin. Reaction pathways of cycloparaffins are determined, and these include ring-opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. The yields and selectivities of over 60 and 140 products, formed during MCH and decalin

  2. Certification testing at low temperatures

    International Nuclear Information System (INIS)

    Noss, P.W.; Ammerman, D.J.

    2004-01-01

    Regulations governing the transport of radioactive materials require that most hypothetical accident condition tests or analyses consider the effects of the environmental temperature that most challenges package performance. For many packages, the most challenging temperature environment is the cold condition (-29 C according to U.S. regulations), primarily because the low temperature causes the highest free drop impact forces due to the higher strength of many energy-absorbing materials at this temperature. If it is decided to perform low temperature testing, it is only necessary that the relevant parts of the package have the required temperature prior to the drop. However, the details of performing a drop at low temperature can have a large influence on testing cost and technical effectiveness. The selection of the test site, the chamber and type of chilling equipment, instrumentation, and even the time of year are all important. Control of seemingly minor details such as the effect on internal pressure, placement of monitoring thermocouples, the thermal time constant of the test article, and icing of equipment are necessary to ensure a successful low temperature test. This paper will discuss these issues and offer suggestions based on recent experience

  3. Studies on the Catalytic Properties of Partially Purified Alkaline Proteases from Some Selected Microorganisms

    Directory of Open Access Journals (Sweden)

    Titilayo Olufunke Femi-Ola

    2012-09-01

    Full Text Available Aims: The research was done to study the conditions enhancing catalytic activities of alkaline proteases from Vibro sp., Lactobacillus brevis, Zymomonas sp., Athrobacter sp., Corynebacterium sp. and Bacillus subtilis.Methodology and Results: The proteolytic enzymes were purified in 2-step procedures involving ammonium sulphate precipitation and sephadex G-150 gel permeation chromatography. The upper and lower limits for the specific activities of proteases from the selected microorganisms were estimated at 20.63 and 47.51 units/mg protein with Zymomonas protease having the highest specific activity towards casein as its substrate and purification fold of 3.46, while that ofLactobacillus brevis protease was 8.06. The native molecular weights of these active proteins ranged from 30.4 to 45.7 kDa with Athrobacter sp. protease having the highest weight for its subunits. The proteolytic enzymes had optimum pH range of 8 to 10 and temperature range of 50 to 62 ºC accounting for the percentage relative activity range of 75 to 94% and 71 to 84 % respectively. The activities of Lactobacillus brevis and Bacillus subtilis proteases were maximum at pH 9 and 10 respectively. Lactobacillus brevis protease activity was maximum at temperature of 62 ºC, while beyond this value, a general thermal instability of these active proteins was observed. At above 70 ºC, the catalytic activities of Corynebacterium sp., Vibrio sp., Zymomonas sp. and Arthrobacter sp. proteases were progressively reduced over a period of 120 min of incubation, while Bacillus subtlis and Lactobacillus brevis proteases were relatively stable. Effect of metal ions was investigated on the catalytic activity of protease from the microorganisms. Lactobacillus brevis,Zymomonas sp., Arthrobacter sp., Corynebacterium sp. and Bacillus subtilis protease activities were strongly activated by metal ions such as Ca+2 and Mg+2. Enzyme activities were inhibited strongly by Cu2+ and Hg2+ but were not

  4. NOx Selective Catalytic Reduction (SCR) on Self-Supported V-W-doped TiO2 Nanofibers

    DEFF Research Database (Denmark)

    Marani, Debora; Silva, Rafael Hubert; Dankeaw, Apiwat

    2017-01-01

    Electrospun V–W–TiO2 catalysts, resulting in a solid solution of V and W in the anatase phase, are prepared as nonwoven nanofibers for NOx selective catalytic reduction (SCR). Preliminary catalytic characterization indicates their superior NOx conversion efficiency to the-state-of-the-art materia...

  5. Catalytic effect of KF-846 on the reforming of the primary intermediates from the co-pyrolysis of pubescens and LDPE

    International Nuclear Information System (INIS)

    Liu, Wen-wu; Hu, Chang-wei; Tong, Dong-mei; Yang, Yu; Li, Gui-ying; Zhu, Liang-fang; Tang, Jin-Qiang

    2014-01-01

    Highlights: • Reforming reactions were inhibited by H 2 , decrease of acidity and low temperature. • There was a synergistic effect on producing hydrogen between Ni and Mo. • The lattice oxygen over catalyst employed might transfer into the intermediates. • Co-pyrolysis, low temperature and N 2 could restrain oxygen transfer to some extent. - Abstract: Co-pyrolysis is regarded as an effective approach to upgrade the quality of pyrolysis products. In this work the activity of KF-846 was evaluated by co-pyrolysis of pubescens and low density polyethylene under different experimental conditions including catalytic mode, pyrolytic atmosphere and temperature, etc. The results showed that the fresh KF-846 exerted strong effects of cyclization, aromatization, hydrogen transfer and vapor-catalytic reforming reactions on the primary intermediates from the co-pyrolysis. The hydrogen-rich gases indicated a synergistic effect between Ni and Mo over KF-846 on producing hydrogen. More importantly, the reforming reactions might be inhibited to some extent by H 2 atmosphere, the low temperature and the decrease of acidity over catalyst. Furthermore, it was deduced that the oxygen over the lattice of catalyst or some intermediates might transfer into other intermediates, possibly resulting in more products with high oxygen content, but it was presumed that the low temperature, co-pyrolysis process and N 2 atmosphere could repress the trend to a certain degree. The mass and energy balance of co-pyrolysis were analyzed, and the main reaction pathways were also proposed. The interference in pyrolysis by regulating the catalytic mode, pyrolytic atmosphere and temperature, acidity over catalyst might posses a certain guiding significance for the pyrolytic technology and the design/selection of catalysts employed

  6. Investigation of combustion and thermodynamic performance of a lean burn catalytic combustion gas turbine system

    International Nuclear Information System (INIS)

    Yin Juan; Weng Yiwu

    2011-01-01

    The goals of this research were to investigate the combustion and thermodynamic performance of a lean burn catalytic combustion gas turbine. The characteristics of lean burn catalytic combustion were investigated by utilising 1D heterogeneous plug flow model which was validated by experiments. The effects of operating parameters on catalytic combustion were numerically analysed. The system models were built in ASPEN Plus and three independent design variables, i.e. compressor pressure ratio (PR), regenerator effectiveness (RE) and turbine inlet temperature (TIT) were selected to analyse the thermodynamic performance of the thermal cycle. The main results show that: simulations from 1D heterogeneous plug flow model can capture the trend of catalytic combustion and describe the behavior of the catalytic monolith in detail. Inlet temperature is the most significant parameter that impacts operation of the catalytic combustor. When TIT and RE are constant, the increase of PR results in lowering the inlet temperature of the catalytic combustor, which results in decreasing methane conversion. The peak thermal efficiency and the optimal PR at a constant TIT increase with the increase of TIT; and at the constant PR, the thermal efficiency increases with the increase of TIT. However, with lower TIT conditions, the optimal PR and the peak efficiency at a constant TIT of the LBCCGT cycle are relative low to that of the conventional cycle. When TIT and PR are constant, the decrease of RE may result in lower methane conversion. The influences of RE on the methane conversion and the thermal efficiency are more significant at higher PRs. The higher thermal efficiency for the lower RE is achieved at lower PR.

  7. System and method for controlling an engine based on ammonia storage in multiple selective catalytic reduction catalysts

    Science.gov (United States)

    Sun, MIn; Perry, Kevin L.

    2015-11-20

    A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

  8. Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides.

    Science.gov (United States)

    Jeong, Hyun-Mook; Jeong, Seong-Yong; Kim, Jae-Hyeok; Kim, Bo-Young; Kim, Jun-Sik; Abdel-Hady, Faissal; Wazzan, Abdulaziz A; Al-Turaif, Hamad Ali; Jang, Ho Won; Lee, Jong-Heun

    2017-11-29

    Co 3 O 4 sensors with a nanoscale TiO 2 or SnO 2 catalytic overlayer were prepared by screen-printing of Co 3 O 4 yolk-shell spheres and subsequent e-beam evaporation of TiO 2 and SnO 2 . The Co 3 O 4 sensors with 5 nm thick TiO 2 and SnO 2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co 3 O 4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

  9. N- vs. C-Domain Selectivity of Catalytic Inactivation of Human Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

    Science.gov (United States)

    Hocharoen, Lalintip; Joyner, Jeff C.; Cowan, J. A.

    2014-01-01

    The N- and C-terminal domains of human somatic Angiotensin I Converting Enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates were tested for both reversible binding and irreversible catalytic inactivation of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of the M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and orientation factors (double-filter effect). PMID:24228790

  10. Experimental investigation on emission reduction in neem oil biodiesel using selective catalytic reduction and catalytic converter techniques.

    Science.gov (United States)

    Viswanathan, Karthickeyan

    2018-05-01

    In the present study, non-edible seed oil namely raw neem oil was converted into biodiesel using transesterification process. In the experimentation, two biodiesel blends were prepared namely B25 (25% neem oil methyl ester with 75% of diesel) and B50 (50% neem oil methyl ester with 50% diesel). Urea-based selective catalytic reduction (SCR) technique with catalytic converter (CC) was fixed in the exhaust tail pipe of the engine for the reduction of engine exhaust emissions. Initially, the engine was operated with diesel as a working fluid and followed by refilling of biodiesel blends B25 and B50 to obtain the baseline readings without SCR and CC. Then, the same procedure was repeated with SCR and CC technique for emission reduction measurement in diesel, B25 and B50 sample. The experimental results revealed that the B25 blend showed higher break thermal efficiency (BTE) and exhaust gas temperature (EGT) with lower break-specific fuel consumption (BSFC) than B50 blend at all loads. On comparing with biodiesel blends, diesel experiences increased BTE of 31.9% with reduced BSFC of 0.29 kg/kWh at full load. A notable emission reduction was noticed for all test fuels in SCR and CC setup. At full load, B25 showed lower carbon monoxide (CO) of 0.09% volume, hydrocarbon (HC) of 24 ppm, and smoke of 14 HSU and oxides of nitrogen (NOx) of 735 ppm than diesel and B50 in SCR and CC setup. On the whole, the engine with SCR and CC setup showed better performance and emission characteristics than standard engine operation.

  11. Variant selection of martensites in steel welded joints with low transformation temperature weld metals

    International Nuclear Information System (INIS)

    Takahashi, Masaru; Yasuda, Hiroyuki Y.

    2013-01-01

    Highlights: ► We examined the variant selection of martensites in the weld metals. ► We also measured the residual stress developed in the butt and box welded joints. ► 24 martensite variants were randomly selected in the butt welded joint. ► High tensile residual stress in the box welded joint led to the strong variant selection. ► We discussed the rule of the variant selection focusing on the residual stress. -- Abstract: Martensitic transformation behavior in steel welded joints with low transformation temperature weld (LTTW) metal was examined focusing on the variant selection of martensites. The butt and box welded joints were prepared with LTTW metals and 980 MPa grade high strength steels. The residual stress of the welded joints, which was measured by a neutron diffraction technique, was effectively reduced by the expansion of the LTTW metals by the martensitic transformation during cooling after the welding process. In the LTTW metals, the retained austenite and martensite phases have the Kurdjumov–Sachs (K–S) orientation relationship. The variant selection of the martensites in the LTTW metals depended strongly on the type of welded joints. In the butt welded joint, 24 K–S variants were almost randomly selected while a few variants were preferentially chosen in the box welded joint. This suggests that the high residual stress developed in the box welded joint accelerated the formation of specific variants during the cooling process, in contrast to the butt welded joint with low residual stress

  12. Low temperature gaseous nitriding of Ni based superalloys

    DEFF Research Database (Denmark)

    Eliasen, K. M.; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2010-01-01

    In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr......In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr...

  13. Low Temperature Synthesis and Properties of Gadolinium-Doped Cerium Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Machado, Marina F. S.; P. R. Moraes, Leticia; Monteiro, Natalia K.

    2017-01-01

    Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte or in composite electrodes. The Ni/GDC cermet can be tuned as a catalytic layer, added to the conventional Ni/yttria-stabilized zirconia (YSZ), for the internal steam...... sintering temperature needed to obtain a fully dense ceramic body, which can result in undesired reactions with YSZ. In this study, a green chemistry route for the synthesis of 10 mol% GDC nanoparticles is proposed. Such a low temperature synthesis provides control over particle size and sinterability...

  14. Low and medium heating value coal gas catalytic combustor characterization

    Science.gov (United States)

    Schwab, J. A.

    1982-01-01

    Catalytic combustion with both low and medium heating value coal gases obtained from an operating gasifier was demonstrated. A practical operating range for efficient operation was determined, and also to identify potential problem areas were identified for consideration during stationary gas turbine engine design. The test rig consists of fuel injectors, a fuel-air premixing section, a catalytic reactor with thermocouple instrumentation and a single point, water cooled sample probe. The test rig included inlet and outlet transition pieces and was designed for installation into an existing test loop.

  15. Reversing flow catalytic converter for a natural gas/diesel dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, E.; Checkel, M.D. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Hayes, R.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Zheng, M.; Mirosh, E. [Alternative Fuel Systems Inc., Calgary, AB (Canada)

    2001-07-01

    An experimental and modelling study was performed for a reverse flow catalytic converter attached to a natural gas/diesel dual fuel engine. The catalytic converter had a segmented ceramic monolith honeycomb substrate and a catalytic washcoat containing a predominantly palladium catalyst. A one-dimensional single channel model was used to simulate the operation of the converter. The kinetics of the CO and methane oxidation followed first-order behaviour. The activation energy for the oxidation of methane showed a change with temperature, dropping from a value of 129 to 35 kJ/mol at a temperature of 874 K. The reverse flow converter was able to achieve high reactor temperature under conditions of low inlet gas temperature, provided that the initial reactor temperature was sufficiently high. (author)

  16. Formulation and catalytic performance of MOF-derived Fe@C/Al composites for high temperature Fischer–Tropsch synthesis

    KAUST Repository

    Oar-Arteta, Lide; Valero-Romero, Marí a José ; Wezendonk, Tim; Kapteijn, Freek; Gascon, Jorge

    2017-01-01

    High productivity towards C-2-C-4 olefins together with high catalyst stability are key for optimum operation in high temperature Fischer-Tropsch synthesis (HT-FTS). Here, we report the fabrication of Fe@C/Al composites that combine both the outstanding catalytic properties of the Fe-BTC MOF-derived Fe catalyst and the excellent mechanical resistance and textural properties provided by the inorganic AlOOH binder. The addition of AlOOH to Fe-BTC followed by pyrolysis in N-2 atmosphere at 500 degrees C results in composites with a large mesoporosity, a high Fe/Fe3O4 ratio, 10-35 nm average Fe crystallite size and coordinatively unsaturated Al3+ sites. In catalytic terms, the addition of AlOOH binder gives rise to enhanced C-2-C-4 selectivity and catalyst mechanical stability in HT-FTS, but at high Al contents the activity decreases. Altogether, the productivity of these Fe@C/Al composites is well above most known Fe catalysts for this process.

  17. Formulation and catalytic performance of MOF-derived Fe@C/Al composites for high temperature Fischer–Tropsch synthesis

    KAUST Repository

    Oar-Arteta, Lide

    2017-11-15

    High productivity towards C-2-C-4 olefins together with high catalyst stability are key for optimum operation in high temperature Fischer-Tropsch synthesis (HT-FTS). Here, we report the fabrication of Fe@C/Al composites that combine both the outstanding catalytic properties of the Fe-BTC MOF-derived Fe catalyst and the excellent mechanical resistance and textural properties provided by the inorganic AlOOH binder. The addition of AlOOH to Fe-BTC followed by pyrolysis in N-2 atmosphere at 500 degrees C results in composites with a large mesoporosity, a high Fe/Fe3O4 ratio, 10-35 nm average Fe crystallite size and coordinatively unsaturated Al3+ sites. In catalytic terms, the addition of AlOOH binder gives rise to enhanced C-2-C-4 selectivity and catalyst mechanical stability in HT-FTS, but at high Al contents the activity decreases. Altogether, the productivity of these Fe@C/Al composites is well above most known Fe catalysts for this process.

  18. Removal of nitrogen compounds from gasification gas by selective catalytic or non-catalytic oxidation; Typpiyhdisteiden poisto kaasutuskaasusta selektiivisellae katalyyttisellae ja ei-katalyyttisellae hapetuksella

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-01

    In gasification reactive nitrogenous compounds are formed from fuel nitrogen, which may form nitrogen oxides in gas combustion. In fluidized bed gasification the most important nitrogenous compound is ammonia (NH{sub 3}). If ammonia could be decomposed to N{sub 2} already before combustion, the emissions if nitrogen oxides could be reduced significantly. One way of increasing the decomposition rate of NH{sub 3} could be the addition of suitable reactants to the gas, which would react with NH{sub 3} and produce N{sub 2}. The aim of this research is to create basic information, which can be used to develop a new method for removal of nitrogen compounds from gasification gas. The reactions of nitrogen compounds and added reactants are studied in reductive atmosphere in order to find conditions, in which nitrogen compounds can be oxidized selectively to N{sub 2}. The project consists of following subtasks: (1) Selective non-catalytic oxidation (SNCO): Reactions of nitrogen compounds and oxidizers in the gas phase, (2) Selective catalytic oxidation (SCO): Reactions of nitrogen compounds and oxidizers on catalytically active surfaces, (3) Kinetic modelling of experimental results in co-operation with the Combustion Chemistry Research Group of Aabo Akademi University. The most important finding has been that NH{sub 3} can be made to react selectively with the oxidizers even in the presence of large amounts of CO and H{sub 2}. Aluminium oxides were found to be the most effective materials promoting selectivity. (author)

  19. Plasma-catalytic reforming of ethanol: influence of air activation rate and reforming temperature

    International Nuclear Information System (INIS)

    Nedybaliuk, O.A.; Chernyak, V.Ya.; Fedirchuk, I.I.; Demchina, V.P.; Bortyshevsky, V.A.; Korzh, R.V.

    2016-01-01

    This paper presents the study of the influence that air activation rate and reforming temperature have on the gaseous products composition and conversion efficiency during the plasma-catalytic reforming of ethanol. The analysis of product composition showed that the conversion efficiency of ethanol has a maximum in the studied range of reforming temperatures. Researched system provided high reforming efficiency and high hydrogen energy yield at the lower temperatures than traditional conversion technologies

  20. Catalytic Reforming of Lignin-Derived Bio-Oil Over a Nanoporous Molecular Sieve Silicoaluminophosphate-11.

    Science.gov (United States)

    Park, Y K; Kang, Hyeon Koo; Jang, Hansaem; Suh, Dong Jin; Park, Sung Hoon

    2016-05-01

    Catalytic pyrolysis of lignin, a major constituent of biomass, was performed. A nanoporous molecular sieve silicoaluminophosphate-11 (SAPO-11) was selected as catalyst. Thermogravimetric analysis showed that 500 degrees C was the optimal pyrolysis temperature. Pyrolyzer-gas chromatography/mass spectroscopy was used to investigate the pyrolysis product distribution. Production of phenolics, the dominant product from the pyrolysis of lignin, was promoted by the increase in the catalyst dose. In particular, low-molecular-mass phenolics were produced more over SAPO-11, while high-molecular-mass phenolics and double-bond-containing phenolics were produced less. The fraction of aromatic compounds, including benzene, toluene, xylene, and ethylbenzene, was also increased by catalytic reforming. The catalytic effects were more pronounced when the catalyst/biomass ratio was increased. The enhanced production of aromatic compounds by an acidic catalyst obtained in this study is in good agreement with the results of previous studies.

  1. Review of Mid- to High-Temperature Solar Selective Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, C. E.

    2002-07-01

    This report describes the concentrating solar power (CSP) systems using solar absorbers to convert concentrated sunlight to thermal electric power. It is possible to achieve solar absorber surfaces for efficient photothermal conversion having high solar absorptance (a) for solar radiation and a low thermal emittance (e) at the operational temperature. A low reflectance (?'' 0) at wavelengths (?) 3 mm and a high reflectance (?'' 1) at l 3 mm characterize spectrally selective surfaces. The operational temperature ranges of these materials for solar applications can be categorized as low temperature (T< 100 C), mid-temperature (100 C< T< 400 C), and high-temperature (T> 400 C). High- and mid-temperature applications are needed for CSP applications. For CSP applications, the ideal spectrally selective surface would be low-cost and easy to manufacture, chemically and thermally stable in air at elevated operating temperatures (T= 500 C), and have a solar absorptance= 0.98 and a thermal emittance= 0.05 at 500 C.

  2. Thermoluminescent system for low temperatures

    International Nuclear Information System (INIS)

    Rosa, L.A.R. da; Caldas, L.V.E.; Leite, N.G.

    1988-09-01

    A system for measurements of the thermoluminescent glow curve, the thermoluminescent emission spectrum and the optical absorption spectrum of solid samples, from liquid nitrogen temperature up to 473 K, is reported. A specially designed temperature programmer provides a linear heating of the sample at a wide range of selectable heating rates, as also long term steady-state temperatures for annealing and isothermal decay studies. The system operates at a pressure of 1.33 x 10 -3 Pa. Presently it is being used for lithium fluoride low temperature thermoluminescent studies. (author) [pt

  3. A new surface catalytic model for silica-based thermal protection material for hypersonic vehicles

    Directory of Open Access Journals (Sweden)

    Li Kai

    2015-10-01

    Full Text Available Silica-based materials are widely employed in the thermal protection system for hypersonic vehicles, and the investigation of their catalytic characteristics is crucially important for accurate aerothermal heating prediction. By analyzing the disadvantages of Norman’s high and low temperature models, this paper combines the two models and proposes an eight-reaction combined surface catalytic model to describe the catalysis between oxygen and silica surface. Given proper evaluation of the parameters according to many references, the recombination coefficient obtained shows good agreement with experimental data. The catalytic mechanisms between oxygen and silica surface are then analyzed. Results show that with the increase of the wall temperature, the dominant reaction contributing to catalytic coefficient varies from Langmuir–Hinshelwood (LH recombination (TW  1350 K. The surface coverage of chemisorption areas varies evidently with the dominant reactions in the high temperature (HT range, while the surface coverage of physisorption areas varies within quite low temperature (LT range (TW < 250 K. Recommended evaluation of partial parameters is also given.

  4. The Effect of Acidic and Redox Properties of V2O5/CeO2-ZrO2 Catalysts in Selective Catalytic Reduction of NO by NH3

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Riisager, Anders; Fehrmann, Rasmus

    2009-01-01

    V2O5 supported ZrO2 and CeO2–ZrO2 catalysts were prepared and characterized by N2 physisorption, XRPD, TPR, and NH3-TPD methods. The influence of calcination temperature from 400 to 600 °C on crystallinity, acidic and redox properties were studied and compared with the catalytic activity...... in the selective catalytic reduction (SCR) of NO with ammonia. The surface area of the catalysts decreased gradually with increasing calcination temperature. The SCR activity of V2O5/ZrO2 catalysts was found to be related with the support crystallinity, whereas V2O5/CeO2–ZrO2 catalysts were also dependent...... on acidic and redox properties of the catalyst. The V2O5/CeO2–ZrO2 catalysts showed high activity and selectivity for reduction of NO with NH3....

  5. Selective catalytic reduction of NO{sub x} to nitrogen over Co-Pt/ZSM-5: Part A. Characterization and kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Maisuls, S.E.; Seshan, K.; Feast, S.; Lercher, J.A. [Laboratory for Catalytic Processes and Materials, Faculty of Chemical Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2001-01-01

    The selective catalytic reduction of NO by propene in the presence of excess oxygen has been studied over catalysts based on Co-Pt supported on ZSM-5. Pure Pt based catalysts are highly active, but produce large amounts of N{sub 2}O. Bimetallic Co-Pt/ZSM-5 catalysts with low Pt contents (0.1wt.%) show a synergistic effect by combining high stability and activity of Pt catalysts with the high N{sub 2} selectivity of Co catalysts. The lower selectivity to N{sub 2}O is attributed to its selective conversion over Co. The catalysts also showed high water and sulfur tolerance above 350C.

  6. Ni-Pt nanoparticles growing on metal organic frameworks (MIL-96) with enhanced catalytic activity for hydrogen generation from hydrazine at room temperature.

    Science.gov (United States)

    Wen, Lan; Du, Xiaoqiong; Su, Jun; Luo, Wei; Cai, Ping; Cheng, Gongzhen

    2015-04-07

    Well-dispersed bimetallic Ni-Pt nanoparticles (NPs) with different compositions have been successfully grown on the MIL-96 by a simple liquid impregnation method using NaBH4 as the reducing agent. Powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, N2 adsorption-desorption, and inductively coupled plasma-atomic emission spectroscopy measurements were employed to characterize the NiPt/MIL-96. Catalytic activity of NiPt/MIL-96 catalysts was tested in the hydrogen generation from the aqueous alkaline solution of hydrazine at room temperature. These catalysts are composition dependent on their catalytic activity, while Ni64Pt36/MIL-96 exhibits the highest catalytic activity among all the catalysts tested, with a turnover frequency value of 114.3 h(-1) and 100% hydrogen selectivity. This excellent catalytic performance might be due to the synergistic effect of the MIL-96 support and NiPt NPs, while NiPt NPs supported on other conventional supports, such as SiO2, carbon black, γ-Al2O3, poly(N-vinyl-2-pyrrolidone) (PVP), and the physical mixture of NiPt and MIL-96, all of them exhibit inferior catalytic activity compared to that of NiPt/MIL-96.

  7. Catalytic and thermal cracking processes of waste cooking oil for bio-gasoline synthesis

    Science.gov (United States)

    Dewanto, Muhammad Andry Rizki; Januartrika, Aulia Azka; Dewajani, Heny; Budiman, Arief

    2017-03-01

    Non-renewable energy resources such as fossil fuels, and coal were depleted as the increase of global energy demand. Moreover, environmental aspect becomes a major concern which recommends people to utilize bio-based resources. Waste cooking oil is one of the economical sources for biofuel production and become the most used raw material for biodiesel production. However, the products formed during frying, can affect the trans-esterification reaction and the biodiesel properties. Therefore, it needs to convert low-quality cooking oil directly into biofuel by both thermal and catalytic cracking processes. Thermal and catalytic cracking sometimes are regarded as prospective bio-energy conversion processes. This research was carried out in the packed bed reactor equipped with 2 stages preheater with temperature of reactor was variated in the range of 450-550°C. At the same temperature, catalytic cracking had been involved in this experiment, using activated ZSM-5 catalyst with 1 cm in length. The organic liquid product was recovered by three stages of double pipe condensers. The composition of cracking products were analyzed using GC-MS instrument and the caloric contents were analyzed using Bomb calorimeter. The results reveal that ZSM-5 was highly selective toward aromatic and long aliphatic compounds formation. The percentage recovery of organic liquid product from the cracking process varies start from 8.31% and the optimal results was 54.08%. The highest heating value of liquid product was resulted from catalytic cracking process at temperature of 450°C with value of 10880.48 cal/gr and the highest product yield with 54.08% recovery was achieved from thermal cracking process with temperature of 450°C.

  8. Catalytic properties of pure and K+-doped Cu O/Mg O system towards 2-propanol conversion

    International Nuclear Information System (INIS)

    El-Molla, S. A.; Amin, N. H.; Hammed, M. N.; Sultan, S. N.; El-Shobaky, G. A.

    2013-01-01

    Cu O/Mg O system having different compositions was prepared by impregnation method followed by calcination at 400-900 C. The effect of Cu O content, calcination temperature and doping with small amounts of K + species (1-3 mol %) on physicochemical, surface and catalytic properties of the system were investigated using X-ray diffraction, adsorption of N 2 at - 196 C, and conversion of isopropyl alcohol at 150-400 C using a flow technique. The results revealed that the solids having the formulae 0.2 and 0.3 Cu O/Mg O calcined at 400 C consisted of nano sized Mg O and Cu O as major phases together with Cu 2 O as minor phase. The Bet-surface areas of different absorbents are decreased by increasing Cu O content, calcination temperature and K + -doping. Mg O-support material showed very small catalytic activity in 2-propanol conversion. The investigated system behaved as selective catalyst for dehydrogenation of 2-propanol with selectivity >80%. The catalytic activity increased by increasing Cu O content and decreased by increasing the calcination temperature within 400-900 C. K + -doping increased the catalytic activity and catalytic durability. (Author)

  9. Voronoi-Tessellated Graphite Produced by Low-Temperature Catalytic Graphitization from Renewable Resources.

    Science.gov (United States)

    Zhao, Leyi; Zhao, Xiuyun; Burke, Luke T; Bennett, J Craig; Dunlap, Richard A; Obrovac, Mark N

    2017-09-11

    A highly crystalline graphite powder was prepared from the low temperature (800-1000 °C) graphitization of renewable hard carbon precursors using a magnesium catalyst. The resulting graphite particles are composed of Voronoi-tessellated regions comprising irregular sheets; each Voronoi-tessellated region having a small "seed" particle located near their centroid on the surface. This suggests nucleated outward growth of graphitic carbon, which has not been previously observed. Each seed particle consists of a spheroidal graphite shell on the inside of which hexagonal graphite platelets are perpendicularly affixed. This results in a unique high surface area graphite with a high degree of graphitization that is made with renewable feedstocks at temperatures far below that conventionally used for artificial graphites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Differences in the catalytic mechanisms of mesophilic and thermophilic indole-3-glycerol phosphate synthase enzymes at their adaptive temperatures.

    Science.gov (United States)

    Zaccardi, Margot J; Mannweiler, Olga; Boehr, David D

    2012-02-10

    Thermophilic enzymes tend to be less catalytically-active at lower temperatures relative to their mesophilic counterparts, despite having very similar crystal structures. An often cited hypothesis for this general observation is that thermostable enzymes have evolved a more rigid tertiary structure in order to cope with their more extreme, natural environment, but they are also less flexible at lower temperatures, leading to their lower catalytic activity under mesophilic conditions. An alternative hypothesis, however, is that complementary thermophilic-mesophilic enzyme pairs simply operate through different evolutionary-optimized catalytic mechanisms. In this communication, we present evidence that while the steps of the catalytic mechanisms for mesophilic and thermophilic indole-3-glycerol phosphate synthase (IGPS) enzymes are fundamentally similar, the identity of the rate-determining step changes as a function of temperature. Our findings indicate that while product release is rate-determining at 25°C for thermophilic IGPS, near its adaptive temperature (75°C), a proton transfer event, involving a general acid, becomes rate-determining. The rate-determining steps for thermophilic and mesophilic IGPS enzymes are also different at their respective, adaptive temperatures with the mesophilic IGPS-catalyzed reaction being rate-limited before irreversible CO2 release, and the thermophilic IGPS-catalyzed reaction being rate limited afterwards. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Performance of a Novel Hydrophobic Mesoporous Material for High Temperature Catalytic Oxidation of Naphthalene

    Directory of Open Access Journals (Sweden)

    Guotao Zhao

    2014-01-01

    Full Text Available A high surface area, hydrophobic mesoporous material, MFS, has been successfully synthesized by a hydrothermal synthesis method using a perfluorinated surfactant, SURFLON S-386, as the single template. N2 adsorption and TEM were employed to characterize the pore structure and morphology of MFS. Static water adsorption test indicates that the hydrophobicity of MFS is significantly higher than that of MCM-41. XPS and Py-GC/MS analysis confirmed the existence of perfluoroalkyl groups in MFS which led to its high hydrophobicity. MFS was used as a support for CuO in experiments of catalytic combustion of naphthalene, where it showed a significant advantage over MCM-41 and ZSM-5. SEM was helpful in understanding why CuO-MFS performed so well in the catalytic combustion of naphthalene. Experimental results indicated that MFS was a suitable support for catalytic combustion of large molecular organic compounds, especially for some high temperature catalytic reactions when water vapor was present.

  12. Catalytic Hydrodeoxygenation of Fatty Acids for Biodiesel Production

    Directory of Open Access Journals (Sweden)

    Аntonina A. Stepacheva

    2016-08-01

    Full Text Available This paper is devoted to the production of second generation biodiesel via catalytic hydrodeoxygenation of fatty acids. Pd/C catalysts with different metal loading were used. The palladium catalysts were characterized using low-temperature nitrogen physisorption and X-ray photoelectron spectroscopy. It was revealed that the most active and selective catalyst was 1%-Pd/C which allowed reaching up 97.5% of selectivity (regarding to n-heptadecane at 100% conversion of substrate. Moreover, the chosen catalyst is more preferable according to lower metal content that leads the decrease of the process cost. The analysis of the catalysts showed that 1%-Pd/C had the highest specific surface area compared with 5%-Pd/C. Copyright © 2016 BCREC GROUP. All rights reserved Received: 31st July 2015; Revised: 9th December 2015; Accepted: 30th December 2015 How to Cite: Stepacheva, A.A., Sapunov, V.N., Sulman, E.M., Nikoshvili, L.Z., Sulman, M.G., Sidorov, A.I., Demidenko, G.N., Matveeva, V.G. (2016. Catalytic Hydrodeoxygenation of Fatty Acids for Biodiesel Production. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 125-132 (doi:10.9767/bcrec.11.2.538.125-132 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.538.125-132

  13. Ni/La2O3 catalyst containing low content platinum-rhodium for the dehydrogenation of N2H4·H2O at room temperature

    Science.gov (United States)

    O, Song-Il; Yan, Jun-Min; Wang, Hong-Li; Wang, Zhi-Li; Jiang, Qing

    2014-09-01

    Ni/La2O3 nanocatalyst with Pt and Rh content as low as 5 mol%, respectively, is successfully synthesized by a facile co-reduction method in the presence of hexadecyl trimethyl ammonium chloride aqueous solution under ambient atmosphere. Interestingly, the resulted Ni/La2O3 catalyst with low cost exhibits excellent catalytic activity to dehydrogenation of hydrous hydrazine (N2H4·H2O), producing hydrogen with 100% selectivity at room temperature (298 K), which represents a promising step toward the practical application for N2H4·H2O system on fuel cells.

  14. Trends in the Catalytic CO Oxidation Activity of Nanoparticles

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Falsig, Hanne; Larsen, Britt Hvolbæk

    2008-01-01

    Going for gold: Density functional calculations show how gold nanoparticles are more active catalysts for CO oxidation than other metal nanoparticles. The high catalytic activity of nanosized gold clusters at low temperature is found to be related to the ability of low-coordinate metal atoms...

  15. Microarray study of temperature-dependent sensitivity and selectivity of metal/oxide sensing interfaces

    Science.gov (United States)

    Tiffany, Jason; Cavicchi, Richard E.; Semancik, Stephen

    2001-02-01

    Conductometric gas microsensors offer the benefits of ppm-level sensitivity, real-time data, simple interfacing to electronics hardware, and low power consumption. The type of device we have been exploring consists of a sensor film deposited on a "microhotplate"- a 100 micron platform with built-in heating (to activate reactions on the sensing surface) and thermometry. We have been using combinatorial studies of 36-element arrays to characterize the relationship between sensor film composition, operating temperature, and response, as measured by the device's sensitivity and selectivity. Gases that have been tested on these arrays include methanol, ethanol, dichloromethane, propane, methane, acetone, benzene, hydrogen, and carbon monoxide, and are of interest in the management of environmental waste sites. These experiments compare tin oxide films modified by catalyst overlayers, and ultrathin metal seed layers. The seed layers are used as part of a chemical vapor deposition process that uses each array element's microheater to activate the deposition of SnO2, and control its microstructure. Low coverage (20 Ê) catalytic metals (Pd, Cu, Cr, In, Au) are deposited on the oxides by masked evaporation or sputtering. This presentation demonstrates the value of an array-based approach for developing film processing methods, measuring performance characteristics, and establishing reproducibility. It also illustrates how temperature-dependent response data for varied metal/oxide compositions can be used to tailor a microsensor array for a given application.

  16. Biological and Biomimetic Low-Temperature Routes to Materials for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Daniel E. [Univ. of California, Santa Barbara, CA (United States). Inst. for Collaborative Biotechnologies

    2016-08-29

    New materials are needed to significantly improve the efficiencies of energy harnessing, transduction and storage, yet the synthesis of advanced composites and multi-metallic semiconductors with nanostructures optimized for these functions remains poorly understood and even less well controlled. To help address this need, we proposed three goals: (1) to further investigate the hierarchical structure of the biologically synthesized silica comprising the skeletal spicules of sponges that we discovered, to better resolve the role and mechanism of templating by the hierarchically assembled silicatein protein filament; (2) to extend our molecular and genetic analyses and engineering of silicatein, the self-assembling, structure-directing, silica-synthesizing enzyme we discovered and characterized, to better understand and manipulate the catalysis and templating of semiconductor synthesis,; and (3) to further investigate, scale up and harness the biologically inspired, low-temperature, kinetically controlled catalytic synthesis method we developed (based on the mechanism we discovered in silicatein) to investigate the kinetic control of the structure-function relationships in magnetic materials, and develop new materials for energy applications. The bio-inspired catalytic synthesis method we have developed is low-cost, low temperature, and operates without the use of polluting chemicals. In addition to direct applications for improvement of batteries and fuel cells, the broader impact of this research includes a deeper fundamental understanding of the factors governing kinetically controlled synthesis and its control of the emergent nanostructure and performance of a wide range of nanomaterials for energy applications.

  17. Low pressure catalytic co-conversion of biogenic waste (rapeseed cake) and vegetable oil.

    Science.gov (United States)

    Giannakopoulou, Kanellina; Lukas, Michael; Vasiliev, Aleksey; Brunner, Christoph; Schnitzer, Hans

    2010-05-01

    Zeolite catalysts of three types (H-ZSM-5, Fe-ZSM-5 and H-Beta) were tested in the catalytic co-conversion of rapeseed cake and safflower oil into bio-fuel. This low pressure process was carried out at the temperatures of 350 and 400 degrees Celsius. The yields and compositions of the product mixtures depended on the catalyst nature and the process temperatures. The produced organic phases consisted mainly of hydrocarbons, fatty acids and nitriles. This mixture possessed improved characteristics (e.g. heating value, water content, density, viscosity, pH) compared with the bio-oils, making possible its application as a bio-fuel. The most effective catalyst, providing the highest yield of organic liquid phase, was the highly acidic/wide-pore H-Beta zeolite. The products obtained on this catalyst demonstrated the highest degree of deoxygenation and the higher HHV (Higher Heating Value). The aqueous liquid phase contained water-soluble carboxylic acids, phenols and heterocyclic compounds. Copyright 2009 Elsevier Ltd. All rights reserved.

  18. Catalytic properties of pure and K{sup +}-doped Cu O/Mg O system towards 2-propanol conversion

    Energy Technology Data Exchange (ETDEWEB)

    El-Molla, S. A.; Amin, N. H.; Hammed, M. N.; Sultan, S. N. [Ain Shams University, Faculty of Education, Chemistry Department, Roxy, Heliopolis, Cairo 11757 (Egypt); El-Shobaky, G. A., E-mail: saharelmolla@yahoo.com [National Research Center, Dokki, Cairo (Egypt)

    2013-08-01

    Cu O/Mg O system having different compositions was prepared by impregnation method followed by calcination at 400-900 C. The effect of Cu O content, calcination temperature and doping with small amounts of K{sup +} species (1-3 mol %) on physicochemical, surface and catalytic properties of the system were investigated using X-ray diffraction, adsorption of N{sub 2} at - 196 C, and conversion of isopropyl alcohol at 150-400 C using a flow technique. The results revealed that the solids having the formulae 0.2 and 0.3 Cu O/Mg O calcined at 400 C consisted of nano sized Mg O and Cu O as major phases together with Cu{sub 2}O as minor phase. The Bet-surface areas of different absorbents are decreased by increasing Cu O content, calcination temperature and K{sup +}-doping. Mg O-support material showed very small catalytic activity in 2-propanol conversion. The investigated system behaved as selective catalyst for dehydrogenation of 2-propanol with selectivity >80%. The catalytic activity increased by increasing Cu O content and decreased by increasing the calcination temperature within 400-900 C. K{sup +}-doping increased the catalytic activity and catalytic durability. (Author)

  19. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane

    International Nuclear Information System (INIS)

    Engelmann Pirez, M.

    2004-12-01

    This work deals with the selective catalytic reduction of nitrogen oxides (NO x ), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N 2 , in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO 3 , on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  20. Adaptive Model Predictive Control of Diesel Engine Selective Catalytic Reduction (SCR) Systems

    Science.gov (United States)

    McKinley, Thomas L.

    2009-01-01

    Selective catalytic reduction or SCR is coming into worldwide use for diesel engine emissions reduction for on- and off-highway vehicles. These applications are characterized by broad operating range as well as rapid and unpredictable changes in operating conditions. Significant nonlinearity, input and output constraints, and stringent performance…

  1. Analysis of heterogeneous oxygen exchange and fuel oxidation on the catalytic surface of perovskite membranes

    KAUST Repository

    Hong, Jongsup

    2013-10-01

    The catalytic kinetics of oxygen surface exchange and fuel oxidation for a perovskite membrane is investigated in terms of the thermodynamic state in the immediate vicinity of or on the membrane surface. Perovskite membranes have been shown to exhibit both oxygen perm-selectivity and catalytic activity for hydrocarbon conversion. A fundamental description of their catalytic surface reactions is needed. In this study, we infer the kinetic parameters for heterogeneous oxygen surface exchange and catalytic fuel conversion reactions, based on permeation rate measurements and a spatially resolved physical model that incorporates detailed chemical kinetics and transport in the gas-phase. The conservation equations for surface and bulk species are coupled with those of the gas-phase species through the species production rates from surface reactions. It is shown that oxygen surface exchange is limited by dissociative/associative adsorption/desorption of oxygen molecules onto/from the membrane surface. On the sweep side, while the catalytic conversion of methane to methyl radical governs the overall surface reactions at high temperature, carbon monoxide oxidation on the membrane surface is dominant at low temperature. Given the sweep side conditions considered in ITM reactor experiments, gas-phase reactions also play an important role, indicating the significance of investigating both homogeneous and heterogeneous chemistry and their coupling when examining the results. We show that the local thermodynamic state at the membrane surface should be considered when constructing and examining models of oxygen permeation and heterogeneous chemistry. © 2013 Elsevier B.V.

  2. Analysis of heterogeneous oxygen exchange and fuel oxidation on the catalytic surface of perovskite membranes

    KAUST Repository

    Hong, Jongsup; Kirchen, Patrick; Ghoniem, Ahmed F.

    2013-01-01

    The catalytic kinetics of oxygen surface exchange and fuel oxidation for a perovskite membrane is investigated in terms of the thermodynamic state in the immediate vicinity of or on the membrane surface. Perovskite membranes have been shown to exhibit both oxygen perm-selectivity and catalytic activity for hydrocarbon conversion. A fundamental description of their catalytic surface reactions is needed. In this study, we infer the kinetic parameters for heterogeneous oxygen surface exchange and catalytic fuel conversion reactions, based on permeation rate measurements and a spatially resolved physical model that incorporates detailed chemical kinetics and transport in the gas-phase. The conservation equations for surface and bulk species are coupled with those of the gas-phase species through the species production rates from surface reactions. It is shown that oxygen surface exchange is limited by dissociative/associative adsorption/desorption of oxygen molecules onto/from the membrane surface. On the sweep side, while the catalytic conversion of methane to methyl radical governs the overall surface reactions at high temperature, carbon monoxide oxidation on the membrane surface is dominant at low temperature. Given the sweep side conditions considered in ITM reactor experiments, gas-phase reactions also play an important role, indicating the significance of investigating both homogeneous and heterogeneous chemistry and their coupling when examining the results. We show that the local thermodynamic state at the membrane surface should be considered when constructing and examining models of oxygen permeation and heterogeneous chemistry. © 2013 Elsevier B.V.

  3. Research and proposal on selective catalytic reduction reactor optimization for industrial boiler.

    Science.gov (United States)

    Yang, Yiming; Li, Jian; He, Hong

    2017-08-24

    The advanced computational fluid dynamics (CFD) software STAR-CCM+ was used to simulate a denitrification (De-NOx) project for a boiler in this paper, and the simulation result was verified based on a physical model. Two selective catalytic reduction (SCR) reactors were developed: reactor 1 was optimized and reactor 2 was developed based on reactor 1. Various indicators, including gas flow field, ammonia concentration distribution, temperature distribution, gas incident angle, and system pressure drop were analyzed. The analysis indicated that reactor 2 was of outstanding performance and could simplify developing greatly. Ammonia injection grid (AIG), the core component of the reactor, was studied; three AIGs were developed and their performances were compared and analyzed. The result indicated that AIG 3 was of the best performance. The technical indicators were proposed for SCR reactor based on the study. Flow filed distribution, gas incident angle, and temperature distribution are subjected to SCR reactor shape to a great extent, and reactor 2 proposed in this paper was of outstanding performance; ammonia concentration distribution is subjected to ammonia injection grid (AIG) shape, and AIG 3 could meet the technical indicator of ammonia concentration without mounting ammonia mixer. The developments above on the reactor and the AIG are both of great application value and social efficiency.

  4. Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2010-08-03

    A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

  5. Catalytic nanoporous membranes

    Science.gov (United States)

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  6. Catalytic conversion of ethanol on H-Y zeolite

    Directory of Open Access Journals (Sweden)

    Čegar Nedeljko

    2005-01-01

    Full Text Available The catalytic activity of the H-form of synthetic zeolite NaY was examined in this study. The catalytic activity was determined according to the rate of ethanol conversion in a gas phase in the static system. In the conversion of ethanol on synthetic NaY zeolite at 585, 595, and 610 K, on which the reaction develops at an optimal rate, ethene and diethyl ether are evolved in approximately the same quantity. After transforming the NaY zeolite into the H-form, its catalytic activity was extremely increases so, the reaction develops at a significantly lower temperature with a very large increase in the reaction rate. The distribution of the products also changes, so that at lower temperatures diethyl ether is elvolved in most cases, and the development of ethene is favored at higher ones, and after a certain period of time there is almost complete conversion of ethanol into ethene. The increase in catalytic activity, as well as the change of selectivity of conversion of ethanol on the H-form of zeolite, is the result of removing Na+ cations in the NaY zeolite, so that more acidic catalyst is obtained which contains a number of acidic catalytically active centers, as well as a more powerful one compared to the original NaY zeolite.

  7. SNCR technology for NO sub x reduction in the cement industry. [Selective non-catalytic reduction

    Energy Technology Data Exchange (ETDEWEB)

    Kupper, D; Brentrup, L [Krupp Polysius AG, Beckum (Germany)

    1992-03-01

    This article discusses the selective non-catalytic (SNCR) process for reducing nitrogen oxides in exhaust gases from cement plants. Topics covered include operating experience, injection of additives, selection of the additive, operating costs, reduction efficiency of SNCR, capital expenditure, secondary emissions and cycles of ammonium. (UK).

  8. Tunable preparation of ruthenium nanoparticles with superior size-dependent catalytic hydrogenation properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuan; Luo, Yaodong; Yang, Xuan; Yang, Yaxin; Song, Qijun, E-mail: qsong@jiangnan.edu.cn

    2017-06-15

    Highlights: • A facile and efficient strategy is firstly developed for the synthesis of Ru NPs. • Ru NPs are stable and uniform with the controllable sizes from 2.6 to 51.5 nm. • Ru NPs exhibit size-dependent and superior catalytic hydrogenation activity. - Abstract: Ruthenium (Ru) featured with an unusual catalytic behavior is of great significance in several heterogeneous and electro-catalytic reactions. The preparation of tractable Ru nanocatalysts and the building of highly active catalytic system at ambient temperature remains a grand challenge. Herein, a facile strategy is developed for the controllable preparation of Ru nanoparticles (NPs) with the sizes ranging from 2.6 to 51.5 nm. Ru NPs show superior size-dependent catalytic performance with the best kinetic rate constant as high as −1.52 min{sup −1}, which could far surpass the other traditional noble metals. Ru NPs exert exceedingly efficient low-temperature catalytic activity and good recyclability in the catalytic reduction of nitroaromatic compounds (NACs) and azo dyes. The developed catalytic system provides a distinguishing insight for the artificial preparation of Ru NPs with desired sizes, and allows for the development of rational design rules for exploring catalysts with superior catalytic performances, potentially broadening the applications of metallic NP-enabled catalytic analysis.

  9. Discovery of a selective catalytic p300/CBP inhibitor that targets lineage-specific tumours

    Energy Technology Data Exchange (ETDEWEB)

    Lasko, Loren M.; Jakob, Clarissa G.; Edalji, Rohinton P.; Qiu, Wei; Montgomery, Debra; Digiammarino, Enrico L.; Hansen, T. Matt; Risi, Roberto M.; Frey, Robin; Manaves, Vlasios; Shaw, Bailin; Algire, Mikkel; Hessler, Paul; Lam, Lloyd T.; Uziel, Tamar; Faivre, Emily; Ferguson, Debra; Buchanan, Fritz G.; Martin, Ruth L.; Torrent, Maricel; Chiang, Gary G.; Karukurichi, Kannan; Langston, J. William; Weinert, Brian T.; Choudhary, Chunaram; de Vries, Peter; Van Drie, John H.; McElligott, David; Kesicki, Ed; Marmorstein, Ronen; Sun, Chaohong; Cole, Philip A.; Rosenberg, Saul H.; Michaelides, Michael R.; Lai, Albert; Bromberg, Kenneth D. (AbbVie); (UCopenhagen); (Petra Pharma); (UPENN); (JHU); (Van Drie); (Faraday)

    2017-09-27

    The dynamic and reversible acetylation of proteins, catalysed by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is a major epigenetic regulatory mechanism of gene transcription1 and is associated with multiple diseases. Histone deacetylase inhibitors are currently approved to treat certain cancers, but progress on the development of drug-like histone actyltransferase inhibitors has lagged behind2. The histone acetyltransferase paralogues p300 and CREB-binding protein (CBP) are key transcriptional co-activators that are essential for a multitude of cellular processes, and have also been implicated in human pathological conditions (including cancer3). Current inhibitors of the p300 and CBP histone acetyltransferase domains, including natural products4, bi-substrate analogues5 and the widely used small molecule C6466,7, lack potency or selectivity. Here, we describe A-485, a potent, selective and drug-like catalytic inhibitor of p300 and CBP. We present a high resolution (1.95 Å) co-crystal structure of a small molecule bound to the catalytic active site of p300 and demonstrate that A-485 competes with acetyl coenzyme A (acetyl-CoA). A-485 selectively inhibited proliferation in lineage-specific tumour types, including several haematological malignancies and androgen receptor-positive prostate cancer. A-485 inhibited the androgen receptor transcriptional program in both androgen-sensitive and castration-resistant prostate cancer and inhibited tumour growth in a castration-resistant xenograft model. These results demonstrate the feasibility of using small molecule inhibitors to selectively target the catalytic activity of histone acetyltransferases, which may provide effective treatments for transcriptional activator-driven malignancies and diseases.

  10. Copper based anodes for bio-ethanol fueled low-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kondakindi, R.R.; Karan, K. [Queen' s Univ., Kingston, ON (Canada)

    2003-07-01

    Laboratory studies have been conducted to develop a low-temperature solid oxide fuel cell (SOFC) fueled by bio-ethanol. SOFCs are considered to be a potential source for clean and efficient electricity. The use of bio-ethanol to power the SOFC contributes even further to reducing CO{sub 2} emissions. The main barrier towards the development of the proposed SOFC is the identification of a suitable anode catalyst that prevents coking during electro-oxidation of ethanol while yielding good electrical performance. Copper was selected as the catalyst for this study. Composite anodes consisting of copper catalysts and gadolinium-doped ceria (GDC) electrolytes were prepared using screen printing of GDC and copper oxide on dense GDC electrolytes and by wet impregnation of copper nitrate in porous GDC electrolytes followed by calcination and sintering. The electrical conductivity of the prepared anodes was characterized to determine the percolation threshold. Temperature-programmed reduction and the Brunner Emmett Teller (BET) methods were used to quantify the catalyst dispersion and surface area. Electrochemical performance of the single-cell SOFC with a hydrogen-air system was used to assess the catalytic activities. Electrochemical Impedance Spectroscopy was used to probe the electrode kinetics.

  11. Catalytic Oxidation of Allylic Alcohols to Methyl Esters

    DEFF Research Database (Denmark)

    Gallas-Hulin, Agata; Kotni, Rama Krishna; Nielsen, Martin

    2017-01-01

    Aerobic oxidation of allylic alcohols to methyl esters using gold nanoparticles supported on different metal oxide carriers has been performed successfully under mild conditions (room temperature, 0.1 MPa O2) without significant loss of catalytic activity. The effects of different reaction...... parameters are studied to find the suitable reaction conditions. All catalysts are characterised by XRD, XRF and TEM. Among these catalysts, Au/TiO2 showed the most efficient catalytic activity towards the selective oxidation of allylic alcohols to the corresponding esters. Moreover, the same Au/TiO2...... to synthesize methyl esters from allylic alcohols....

  12. Methodology study for the catalyst obtention to low temperature fuel cells (DEFC)

    International Nuclear Information System (INIS)

    Oliveira, Emilia Lucena de; Korb, Matias De Angelis; Correa, Patricia dos Santos; Radtke, Claudio; Malfatti, Celia de Fraga; Rieder, Ester

    2010-01-01

    Different methods to elaboration of catalysts in direct ethanol fuel cells (low temperature fuel cells) have been proposed in the literature. The present work aims to study a simplified methodology to obtain Pt-Sn-Ni alloys, used as catalysts in low temperature fuel cells. Impregnation/reduction method was employed to obtain Pt- Sn-Ni alloys supported on carbon, using ethylenoglycol as reductor agent and carbon Vulcan XC72R as support. Different amounts of Pt, Sn e Ni were studied, with the intent to obtain the maximum catalytic effect. The catalysts were obtained in an alkaline range, at 130 deg C, using the proportion ethylenoglycol:water 75/25 v/v. The analytical techniques used in this study was RBS (Rutherford Backscattering Spectroscopy), X Ray Diffraction and Cyclic Voltammetry. (author)

  13. A low-barrier hydrogen bond mediates antibiotic resistance in a noncanonical catalytic triad

    Science.gov (United States)

    2018-01-01

    One group of enzymes that confer resistance to aminoglycoside antibiotics through covalent modification belongs to the GCN5-related N-acetyltransferase (GNAT) superfamily. We show how a unique GNAT subfamily member uses a previously unidentified noncanonical catalytic triad, consisting of a glutamic acid, a histidine, and the antibiotic substrate itself, which acts as a nucleophile and attacks the acetyl donor molecule. Neutron diffraction studies allow for unambiguous identification of a low-barrier hydrogen bond, predicted in canonical catalytic triads to increase basicity of the histidine. This work highlights the role of this unique catalytic triad in mediating antibiotic resistance while providing new insights into the design of the next generation of aminoglycosides. PMID:29632894

  14. Catalytic exhaust control

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, H

    1973-09-01

    Recent achievements and problems in the development of exhaust control devices in the USA are reviewed. To meet the 1976 emission standards, catalytic systems for the oxidation of carbon monoxide and hydrocarbons and for the reduction of nitrogen oxides to nitrogen and water are needed. While oxidizing catalysts using platinum, palladium, copper, vanadium, and chromium appplied on alumina or ceramic materials are more or less effective in emission control, there are no catalytic devices for the reduction of nitrogen oxides with the required useful life of 25,000 to 50,000 miles as yet available. In the case of platinum catalysts on monolithic supports, the operating temperature of 650 to 750/sup 0/C as required for the oxidation process may cause inactivation of the catalysts and fusion of the support material. The oxidation of CO and hydrocarbons is inhibited by high concentrations of CO, nitric oxide, and hydrocarbons. The use of catalytic converters requires the use of lead-free or low-lead gasoline. The nitrogen oxides conversion efficiency is considerably influenced by the oxygen-to-CO ratio of the exhaust gas, which makes limitation of this ratio necessary.

  15. COST OF SELECTIVE CATALYTIC REDUCTION (SCR) APPLICATION FOR NOX CONTROL ON COAL-FIRED BOILERS

    Science.gov (United States)

    The report provides a methodology for estimating budgetary costs associated with retrofit applications of selective catalytic reduction (SCR) technology on coal-fired boilers. SCR is a postcombustion nitrogen oxides (NOx) control technology capable of providing NOx reductions >90...

  16. Particle size effects in the catalytic electroreduction of CO₂ on Cu nanoparticles.

    Science.gov (United States)

    Reske, Rulle; Mistry, Hemma; Behafarid, Farzad; Roldan Cuenya, Beatriz; Strasser, Peter

    2014-05-14

    A study of particle size effects during the catalytic CO2 electroreduction on size-controlled Cu nanoparticles (NPs) is presented. Cu NP catalysts in the 2-15 nm mean size range were prepared, and their catalytic activity and selectivity during CO2 electroreduction were analyzed and compared to a bulk Cu electrode. A dramatic increase in the catalytic activity and selectivity for H2 and CO was observed with decreasing Cu particle size, in particular, for NPs below 5 nm. Hydrocarbon (methane and ethylene) selectivity was increasingly suppressed for nanoscale Cu surfaces. The size dependence of the surface atomic coordination of model spherical Cu particles was used to rationalize the experimental results. Changes in the population of low-coordinated surface sites and their stronger chemisorption were linked to surging H2 and CO selectivities, higher catalytic activity, and smaller hydrocarbon selectivity. The presented activity-selectivity-size relations provide novel insights in the CO2 electroreduction reaction on nanoscale surfaces. Our smallest nanoparticles (~2 nm) enter the ab initio computationally accessible size regime, and therefore, the results obtained lend themselves well to density functional theory (DFT) evaluation and reaction mechanism verification.

  17. Catalytic Ethanol Dehydration over Different Acid-activated Montmorillonite Clays.

    Science.gov (United States)

    Krutpijit, Chadaporn; Jongsomjit, Bunjerd

    2016-01-01

    In the present study, the catalytic dehydration of ethanol to obtain ethylene over montmorillonite clays (MMT) with mineral acid activation including H2SO4 (SA-MMT), HCl (HA-MMT) and HNO3 (NA-MMT) was investigated at temperature range of 200 to 400°C. It revealed that HA-MMT exhibited the highest catalytic activity. Ethanol conversion and ethylene selectivity were found to increase with increased reaction temperature. At 400°C, the HA-MMT yielded 82% of ethanol conversion having 78% of ethylene yield. At lower temperature (i.e. 200 to 300°C), diethyl ether (DEE) was a major product. The highest activity obtained from HA-MMT can be attributed to an increase of weak acid sites and acid density by the activation of MMT with HCl. It can be also proven by various characterization techniques that in most case, the main structure of MMT did not alter by acid activation (excepted for NA-MMT). Upon the stability test for 72 h during the reaction, the MMT and HA-MMT showed only slight deactivation due to carbon deposition. Hence, the acid activation of MMT by HCl is promising to enhance the catalytic dehydration of ethanol.

  18. Influence of the Crystal Structure of Titanium Oxide on the Catalytic Activity of Rh/TiO2 in Steam Reforming of Propane at Low Temperature.

    Science.gov (United States)

    Yu, Lin; Sato, Katsutoshi; Toriyama, Takaaki; Yamamoto, Tomokazu; Matsumura, Syo; Nagaoka, Katsutoshi

    2018-05-01

    Solid oxide fuel cells (SOFCs) using liquefied petroleum gas(LPG) reduce CO2 emissions due to their high energy-conversion efficiency. Although SOFCs can convert LPG directly, coking occurs easily by decomposition of hydrocarbons, including C-C bonds on the electrode of fuel cell stacks. It is therefore necessary to develop an active steam pre-reforming catalyst that eliminates the hydrocarbons at low temperature, where waste heat of SOFCs is used. Here we show that the crystal structure of the TiO2 that anchors Rh particles is crucial for catalytic activity of Rh/TiO2 catalysts for propane pre-reforming. Our experimental results revealed that strong metal support interaction (SMSI) induced during H2 pre-reduction were optimized over Rh/TiO2 with a rutile structure; this catalyst catalyzed the reaction much more effectively than conventional Rh/γ-Al2O3. In contrast, the SMSI was too strong for Rh/TiO2 with an anatase structure, and the surface of the Rh particles was therefore covered mostly with partially reduced TiO2. The result was very low activity. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NOx reduction with NH3

    Science.gov (United States)

    Pourkhalil, Mahnaz; Moghaddam, Abdolsamad Zarringhalam; Rashidi, Alimorad; Towfighi, Jafar; Mortazavi, Yadollah

    2013-08-01

    Manganese oxide catalysts (MnOx) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by the incipient wetness impregnation method. These catalysts were characterized by N2 adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H2-temperature programmed reduction (H2-TPR) methods. The effects of reaction temperature, MnOx loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NOx with NH3. Under the reaction conditions of 200 °C, 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol%, GHSV = 30,000 h-1 and 12 wt% MnOx, NOx conversion and N2 selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO2 and 2.5 vol% H2O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.

  20. Durability and regeneration of catalysts of the iron family in hydrogenation of low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Funasaka, W; Yokogawa, C; Hayashi, K; Kawamura, T; Fujita, H; Suga, S

    1949-01-01

    The low-temperature tar consisting of neutral and acidic oils has been reduced under atmospheric pressure between 400/sup 0/ and 500/sup 0/ by using catalysts prepared from Fe-Cr-kieselguhr, yellow ocher, and other material. When the reduction was performed at 480/sup 0/ with the yellow ocher from Niwasaka, Fukushima Prefacture, Japan, the low-temperature tar was easily converted to neutral and light oils and the catalysts could be regenerated by repeated baking and reduction. It is concluded that the commercialization of this reduction process is possible by using a cycle (each takes 20 minutes) composed of catalytic reaction, baking, and reduction of the catalysts.

  1. Chemiluminescence analyzer of NOx as a high-throughput screening tool in selective catalytic reduction of NO

    International Nuclear Information System (INIS)

    Oh, Kwang Seok; Woo, Seong Ihl

    2011-01-01

    A chemiluminescence-based analyzer of NO x gas species has been applied for high-throughput screening of a library of catalytic materials. The applicability of the commercial NO x analyzer as a rapid screening tool was evaluated using selective catalytic reduction of NO gas. A library of 60 binary alloys composed of Pt and Co, Zr, La, Ce, Fe or W on Al 2 O 3 substrate was tested for the efficiency of NO x removal using a home-built 64-channel parallel and sequential tubular reactor. The NO x concentrations measured by the NO x analyzer agreed well with the results obtained using micro gas chromatography for a reference catalyst consisting of 1 wt% Pt on γ-Al 2 O 3 . Most alloys showed high efficiency at 275 °C, which is typical of Pt-based catalysts for selective catalytic reduction of NO. The screening with NO x analyzer allowed to select Pt-Ce (X) (X=1–3) and Pt–Fe (2) as the optimal catalysts for NO x removal: 73% NO x conversion was achieved with the Pt–Fe (2) alloy, which was much better than the results for the reference catalyst and the other library alloys. This study demonstrates a sequential high-throughput method of practical evaluation of catalysts for the selective reduction of NO.

  2. Substrate-Directed Catalytic Selective Chemical Reactions.

    Science.gov (United States)

    Sawano, Takahiro; Yamamoto, Hisashi

    2018-05-04

    The development of highly efficient reactions at only the desired position is one of the most important subjects in organic chemistry. Most of the reactions in current organic chemistry are reagent- or catalyst-controlled reactions, and the regio- and stereoselectivity of the reactions are determined by the inherent nature of the reagent or catalyst. In sharp contrast, substrate-directed reaction determines the selectivity of the reactions by the functional group on the substrate and can strictly distinguish sterically and electronically similar multiple reaction sites in the substrate. In this Perspective, three topics of substrate-directed reaction are mainly reviewed: (1) directing group-assisted epoxidation of alkenes, (2) ring-opening reactions of epoxides by various nucleophiles, and (3) catalytic peptide synthesis. Our newly developed synthetic methods with new ligands including hydroxamic acid derived ligands realized not only highly efficient reactions but also pinpointed reactions at the expected position, demonstrating the substrate-directed reaction as a powerful method to achieve the desired regio- and stereoselective functionalization of molecules from different viewpoints of reagent- or catalyst-controlled reactions.

  3. Low-Temperature Catalytic Performance of Ni-Cu/Al2O3 Catalysts for Gasoline Reforming to Produce Hydrogen Applied in Spark Ignition Engines

    Directory of Open Access Journals (Sweden)

    Le Anh Tuan

    2016-03-01

    Full Text Available The performance of Ni-Cu/Al2O3 catalysts for steam reforming (SR of gasoline to produce a hydrogen-rich gas mixture applied in a spark ignition (SI engine was investigated at relatively low temperature. The structural and morphological features and catalysis activity were observed by X-ray diffractometry (XRD, scanning electron microscopy (SEM, and temperature programmed reduction (TPR. The results showed that the addition of copper improved the dispersion of nickel and therefore facilitated the reduction of Ni at low temperature. The highest hydrogen selectivity of 70.6% is observed over the Ni-Cu/Al2O3 catalysts at a steam/carbon ratio of 0.9. With Cu promotion, a gasoline conversion of 42.6% can be achieved at 550 °C, while with both Mo and Ce promotion, the gasoline conversions were 31.7% and 28.3%, respectively, higher than with the conventional Ni catalyst. On the other hand, initial durability testing showed that the conversion of gasoline over Ni-Cu/Al2O3 catalysts slightly decreased after 30 h reaction time.

  4. Low-temperature kinetic measurements of microsecond freeze-hyperquench (MHQ) cytochrome oxidase monitored by UV-visible spectroscopy with a newly designed cuvette.

    Science.gov (United States)

    Wiertz, F G M; de Vries, S

    2006-02-01

    A special cuvette was designed to measure optical changes of MHQ (microsecond freeze-hyperquench) powder samples at temperatures below approx. 250 K. Reduced cytochrome c oxidase from Paracoccus denitrificans was reacted with O(2) for 100 micros, frozen as a powder and transferred to the cuvette. Subsequently, cytochrome oxidase was allowed to react further following stepwise increments of the temperature from 100 K up to 250 K while recording spectra between 300 and 700 nm. The temperature was raised only when no further changes in the spectra could be detected. The experiment yielded spectra of the A, P(M), F and O intermediate states. This demonstrated that the catalytic cycle of cytochrome oxidase at low temperature is similar to that at room temperature and so verifies the suitability of this method for the study of enzymes with high catalytic-centre activity.

  5. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  6. Catalytic fast pyrolysis of durian rind using silica-alumina catalyst: Effects of pyrolysis parameters.

    Science.gov (United States)

    Tan, Y L; Abdullah, A Z; Hameed, B H

    2018-05-18

    Silica-alumina catalyst was prepared and used in the catalytic fast pyrolysis of durian rind in a drop-type two-stage reactor. The effects of catalytic temperature (400 °C-600 °C) and catalyst-to-durian rind ratio (1:30-3:30) were evaluated. Bio-oil yield was increased with increased catalytic temperature due to considerable dehydration process, but it was reduced with high catalyst loading due to the overcracking of organics into light gases. Silica-alumina catalyst possessed good selectivity and the products changed according to the temperature. The major components in bio-oil were hydrocarbons, furan derivatives, and aromatic compounds at 400 °C, 500 °C, and 600 °C, respectively. The hydrogen and carbon contents of bio-oil were reduced with high catalyst loading due to the overcracking of organics, and the deoxygenation process became unfavorable. The silica-alumina catalyst worked well in catalytic fast pyrolysis of durian rind, and the condition may be adjusted based on the desired products. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. A 25 kWe low concentration methane catalytic combustion gas turbine prototype unit

    International Nuclear Information System (INIS)

    Su, Shi; Yu, Xinxiang

    2015-01-01

    Low concentration methane, emitted from various industries e.g. coal mines and landfills into atmosphere, is not only an important greenhouse gas, but also a wasted energy resource if not utilized. In the past decade, we have been developing a novel VAMCAT (ventilation air methane catalytic combustion gas turbine) technology. This turbine technology can be used to mitigate methane emissions for greenhouse gas reduction, and also to utilize the low concentration methane as an energy source. This paper presents our latest research results on the development and demonstration of a 25 kWe lean burn catalytic combustion gas turbine prototype unit. Recent experimental results show that the unit can be operated with 0.8 vol% of methane in air, producing about 19–21 kWe of electricity output. - Highlights: • A novel low concentration methane catalytic turbine prototype unit was developed. • The 25 kWe unit can be operated with ∼0.8 vol.% CH 4 in air with 19–21 kWe output. • A new start-up method was developed for the prototype unit

  8. Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation

    KAUST Repository

    Imran, Ali

    2016-03-11

    Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liquid yield due to the increased production of non-condensables, primarily hydrocarbons. The catalytically produced bio-oil was less viscous and zeolites were effective at cracking heavy molecular weight compounds in the bio-oil. Acidic zeolites, H-Y and H-ZSM5, increased the desirable chemical compounds in the bio-oil such as phenols, furans and hydrocarbon, and reduced the undesired compounds such as acids. On the other hand reducing the acidity of zeolites reduced some of the undesired compounds in the bio-oil such as ketones and aldehydes. The performance of H-Y was superior to that of the rest of zeolites studied: bio-oil of high chemical and calorific value was produced with a high organic liquid yield and low oxygen content. H-ZSM5 was a close competitor to H-Y in performance but with a lower yield of bio-oil. Online fractionation of catalytic pyrolysis vapors was employed by controlling the condenser temperature and proved to be a successful process parameter to tailor the

  9. Morphological effects on the selectivity of intramolecular versus intermolecular catalytic reaction on Au nanoparticles.

    Science.gov (United States)

    Wang, Dan; Sun, Yuanmiao; Sun, Yinghui; Huang, Jing; Liang, Zhiqiang; Li, Shuzhou; Jiang, Lin

    2017-06-14

    It is hard for metal nanoparticle catalysts to control the selectivity of a catalytic reaction in a simple process. In this work, we obtain active Au nanoparticle catalysts with high selectivity for the hydrogenation reaction of aromatic nitro compounds, by simply employing spine-like Au nanoparticles. The density functional theory (DFT) calculations further elucidate that the morphological effect on thermal selectivity control is an internal key parameter to modulate the nitro hydrogenation process on the surface of Au spines. These results show that controlled morphological effects may play an important role in catalysis reactions of noble metal NPs with high selectivity.

  10. The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter.

    Science.gov (United States)

    Mihai, Oana; Tamm, Stefanie; Stenfeldt, Marie; Olsson, Louise

    2016-02-28

    A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O2 and H2O at low temperature (150, 175 and 200°C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150°C, which shows that there is a reaction with these species and soot. In addition, the conversion of NOx due to NO2 SCR was significantly enhanced in the presence of soot; we attribute this to the smaller amount of ammonium nitrate species present in the experiments where soot is available since it is well known that ammonium nitrate formation is a major problem at low temperature due to the blocking of the catalytic sites. Further, a scanning electron microscopy analysis of the soot particles shows that they are about 30-40 nm and are therefore too large to enter the pores of the zeolites. There are likely CuxOy or other copper species available on the outside of the zeolite crystallites, which could have been enhanced due to the hydrothermal treatment at 850°C of the SCR-coated filter prior to the soot loading. We therefore propose that soot is

  11. Structural insights into the loss of catalytic competence in pectate lyase activity at low pH

    DEFF Research Database (Denmark)

    Ali, Salyha; Søndergaard, Chresten Rauff; Teixeira, Susana

    2015-01-01

    at the active centre (+1 subsite), they withdraw electrons acidifying the C5 proton facilitating its abstraction by the catalytic arginine. Here we show that activity is lost at low pH because protonation of aspartates results in the loss of the two catalytic calcium-ions causing a profound failure to correctly...

  12. Co and Fe-catalysts supported on sepiolite: effects of preparation conditions on their catalytic behaviors in high temperature gas flow treatment of dye.

    Science.gov (United States)

    Lin, Xiangfeng; Fang, Jian; Chen, Menglin; Huang, Zhi; Su, Chengyuan

    2016-08-01

    An efficient adsorbent/catalyst Co and Fe-catalysts loaded on sepiolite (Co-Fe/sepiolite) was successfully prepared for high temperature gas flow catalytic reaction by a simple impregnation method. The impact of preparation conditions (such as pH value of impregnation solution, impregnation time, calcination temperature, and time) on catalytic activity was studied. We found that the catalytic activity of Co-Fe/sepiolite was strongly influenced by all the investigated parameters. The regeneration efficiency (RE) was used to evaluate the catalytic activity. The RE is more noticeable at pH 5.0 of impregnation solution, impregnation time 18 h, calcination temperature 650 °C, and calcination time 3 h. This Co-Fe/sepiolite has great adsorption capacity in absorbing dye. It is used for an adsorbent to adsorb dye from wastewater solution under dynamic adsorption and saturated with dye, then regenerated with high temperature gas flow for adsorption/oxidation cycles. The Co-Fe/sepiolite acts as a catalyst to degrade the dye during regeneration under high temperature gas flow. Hence, the Co-Fe/sepiolite is not only an adsorbent but also a catalyst. The Co-Fe/sepiolite is more stable than sepiolite when applied in the treatment of plant's wastewater. The Co-Fe/sepiolite can be reused in adsorption-regeneration cycle. The results indicate the usability of the proposed combined process, dye adsorption on Co-Fe/sepiolite followed by the catalytic oxidation in high temperature gas flow.

  13. Catalytic chemical amide synthesis at room temperature: one more step toward peptide synthesis.

    Science.gov (United States)

    Mohy El Dine, Tharwat; Erb, William; Berhault, Yohann; Rouden, Jacques; Blanchet, Jérôme

    2015-05-01

    An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.

  14. Catalytic oxidation of dibromomethane over Ti-modified Co3O4 catalysts: Structure, activity and mechanism.

    Science.gov (United States)

    Mei, Jian; Huang, Wenjun; Qu, Zan; Hu, Xiaofang; Yan, Naiqiang

    2017-11-01

    Ti-modified Co 3 O 4 catalysts with various Co/Ti ratios were synthesized using the co-precipitation method and were used in catalytic oxidation of dibromomethane (CH 2 Br 2 ), which was selected as the model molecule for brominated volatile organic compounds (BVOCs). Addition of Ti distorted the crystal structure and led to the formation of a Co-O-Ti solid solution. Co 4 Ti 1 (Co/Ti molar ratio was 4) achieved higher catalytic activity with a T 90 (the temperature needed for 90% conversion) of approximately 245°C for CH 2 Br 2 oxidation and higher selectivity to CO 2 at a low temperature than the other investigated catalysts. In addition, Co 4 Ti 1 was stable for at least 30h at 500ppm CH 2 Br 2 , 0 or 2vol% H 2 O, 0 or 500ppm p-xylene (PX), and 10% O 2 at a gas hourly space velocity of 60,000h -1 . The final products were CO x , Br 2 , and HBr, without the formation of other Br-containing organic byproducts. The high catalytic activity was attributed to the high Co 3+ /Co 2+ ratio and high surface acidity. Additionally, the synergistic effect of Co and Ti made it superior for CH 2 Br 2 oxidation. Furthermore, based on the analysis of products and in situ DRIFTs studies, a receivable reaction mechanism for CH 2 Br 2 oxidation over Ti-modified Co 3 O 4 catalysts was proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Effect of Calcination Temperatures and Mo Modification on Nanocrystalline (γ-χ-Al2O3 Catalysts for Catalytic Ethanol Dehydration

    Directory of Open Access Journals (Sweden)

    Tharmmanoon Inmanee

    2017-01-01

    Full Text Available The mixed gamma and chi crystalline phase alumina (M-Al catalysts prepared by the solvothermal method were investigated for catalytic ethanol dehydration. The effects of calcination temperatures and Mo modification were elucidated. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, transmission electron microscopy (TEM, and NH3-temperature programmed desorption (NH3-TPD. The catalytic activity was tested for ethylene production by dehydration reaction of ethanol in gas phase at atmospheric pressure and temperature between 200°C and 400°C. It was found that the calcination temperatures and Mo modification have effects on acidity of the catalysts. The increase in calcination temperature resulted in decreased acidity, while the Mo modification on the mixed phase alumina catalyst yielded increased acidity, especially in medium to strong acids. In this study, the catalytic activity of ethanol dehydration to ethylene apparently depends on the medium to strong acid. The mixed phase alumina catalyst calcined at 600°C (M-Al-600 exhibits the complete ethanol conversion having ethylene yield of 98.8% (at 350°C and the Mo-modified catalysts promoted dehydrogenation reaction to acetaldehyde. This can be attributed to the enhancement of medium to strong acid with metal sites of catalyst.

  16. Ionometric determination of fluorides at low temperatures

    International Nuclear Information System (INIS)

    Kostyukova, I.S.; Ennan, A.A.; Dzerzhko, E.K.; Leivikova, A.A.

    1995-01-01

    A method for determining fluoride ions in solution at low temperatures using a solid-contact fluorine-selective electrode (FSE) has been developed. The effect of temperature (60 to -15 degrees C) on the calibration slope, potential equilibrium time, and operational stability is studied; the effect of an organic additive (cryoprotector) on the calibration slope is also studied. The temperature relationships obtained for the solid-contact FSEs allow appropriate corrections to be applied to the operational algorithm of the open-quotes Ftoringclose quotes hand-held semiautomatic HF gas analyzer for the operational temperature range of -16 to 60 degrees C

  17. Low temperature catalytic reforming of heptane to hydrogen and syngas

    Directory of Open Access Journals (Sweden)

    M.E.E. Abashar

    2016-09-01

    Full Text Available The production of hydrogen and syngas from heptane at a low temperature is studied in a circulating fast fluidized bed membrane reactor (CFFBMR. A thin film of palladium-based membrane is employed to the displacement of the thermodynamic equilibrium for high conversion and yield. A mathematical model is developed to simulate the reformer. A substantial improvement of the CFFBMR is achieved by implementing the thin hydrogen membrane. The results showed that almost complete conversion of heptane and 46.25% increase of exit hydrogen yield over the value without membrane are achieved. Also a wide range of the H2/CO ratio within the recommended industrial range is obtained. The phenomena of high spikes of maximum nature at the beginning of the CFFBMR are observed and explanation offered. The sensitivity analysis results have shown that the increase of the steam to carbon feed ratio can increase the exit hydrogen yield up to 108.29%. It was found that the increase of reaction side pressure at a high steam to carbon feed ratio can increase further the exit hydrogen yield by 49.36% at a shorter reactor length. Moreover, the increase of reaction side pressure has an important impact in a significant decrease of the carbon dioxide and this is a positive sign for clean environment.

  18. Environmental and economic evaluation of selective non-catalytic reduction of nitrogen oxides

    Science.gov (United States)

    Parchevskii, V. M.; Shchederkina, T. E.; Proshina, A. O.

    2017-11-01

    There are two groups of atmosphere protecting measures: technology (primary) and treatment (secondary). When burning high-calorie low-volatile brands of coals in the furnaces with liquid slag removal to achieve emission standards required joint use of these two methods, for example, staged combustion and selective non-catalytic reduction recovery (SNCR). For the economically intelligent combination of these two methods it is necessary to have information not only about the environmental performance of each method, but also the operating costs per unit of reduced emission. The authors of this report are made an environmental-economic analysis of SNCR on boiler Π-50P Kashirskaya power station. The obtained results about the dependence of costs from the load of the boiler and the mass emissions of nitrogen oxides then approximates into empirical formulas, is named as environmental and economic characteristics, which is suitable for downloading into controllers and other control devices for subsequent implementation of optimal control of emissions to ensure compliance with environmental regulations at the lowest cost at any load of the boiler.

  19. Catalytic Destruction of a Surrogate Organic Hazardous Air Pollutant as a Potential Co-benefit for Coal-fired Selective Catalyst Reduction Systems

    Science.gov (United States)

    Catalytic destruction of benzene (C6H6), a surrogate for organic hazardous air pollutants (HAPs) produced from coal combustion, was investigated using a commercial selective catalytic reduction (SCR) catalyst for evaluating the potential co-benefit of the SCR technology for reduc...

  20. Catalytic Cracking of Lactide and Poly(Lactic Acid) to Acrylic Acid at Low Temperatures.

    Science.gov (United States)

    Terrade, Frédéric G; van Krieken, Jan; Verkuijl, Bastiaan J V; Bouwman, Elisabeth

    2017-05-09

    Despite being a simple dehydration reaction, the industrially relevant conversion of lactic acid to acrylic acid is particularly challenging. For the first time, the catalytic cracking of lactide and poly(lactic acid) to acrylic acid under mild conditions is reported with up to 58 % yield. This transformation is catalyzed by strong acids in the presence of bromide or chloride salts and proceeds through simple S N 2 and elimination reactions. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. Development of selective catalytic oxidation (SCO) for NH{sub 3} and HCN removal from gasification gas; Selektiivisen katalyyttisen hapetusprosessin (SCO) kehittaeminen kaasutuskaasun NH{sub 3}:n ja HCN:n poistoon

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T.; Heiskanen, K. [VTT Energy, Espoo (Finland)

    1997-10-01

    In gasification, reactive nitrogen compounds (mainly NH{sub 3} and HCN) are formed from fuel nitrogen. If the gas containing NH{sub 3} is burned, a high NO{sub x} emission may be formed. The content of nitrogen compounds of the hot gasification gas could be reduced in Selective Catalytic Oxidation (SCO) process. In this process small amounts of reactive oxidisers are injected into the gas in order to convert NH{sub 3} to N{sub 2}. The utilization of SCO process together with low NO{sub x} burners in advanced gasification power stations might offer an alternative for flue gas treatment technologies like SCR (Selective Catalytic Reduction). In the earlier research, conditions were found, where oxidizers reacted selectively with ammonia in the gasification gas. Highest ammonia reduction took place in the aluminium oxide bed in the presence of NO and O{sub 2}. The aim of this study is to examine the reaction mechanism in order to be able to further evaluate the development possibilities of this kind process. The effect of composition and the amount of added oxidizer, the content of combustible gas components, space velocity, pressure and temperature will be studied. The experiments are carried out with the laboratory scale high pressure flow reactor of VTT Energy. Kinetic modelling of the experimental results is carried out in co-operation with the combustion chemistry group of Aabo Akademi. The aim of the modelling work is to bring insight to the gas-phase reactions that are important for the SCO-process. (orig.)

  2. Promotion of catalytic performance by adding W into Pt/ZrO{sub 2} catalyst for selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Mengmeng [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, Sichuan (China); Wang, Suning; Li, Yuanshan [College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Xu, Haidi, E-mail: xuhaidi@scu.edu.cn [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, Sichuan (China); Chen, Yaoqiang, E-mail: nic7501@scu.edu.cn [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610064, Sichuan (China); College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China)

    2017-04-30

    Highlights: • The tungsten species weaken platinum-oxygen bond strength. • Pt{sup 0} was the active species of ammonia oxidation reaction in the low temperature. • Some PtO species could convert to Pt [111] beside WO{sub 3} species. - Abstract: Pt-WO{sub 3}/ZrO{sub 2} catalyst was prepared by co-impregnation method to improve the ammonia oxidation performance of Pt/ZrO{sub 2}. Differences in textural, structural, surface chemical states, redox properties and acid properties, together with the catalytic performance of Pt/ZrO{sub 2} and Pt-WO{sub 3}/ZrO{sub 2} catalysts were investigated systematically. The results of H{sub 2}-TPR revealed that higher reduction ability was possessed by Pt-WO{sub 3}/ZrO{sub 2} than that of Pt/ZrO{sub 2} due to the influence of tungsten on platinum. The XPS results showed that electron transfer from tungsten to platinum species made higher electron density around platinum. The TEM results revealed that the active lattice plane Pt[111] was obtained by modification of W species. Consequently, Pt-WO{sub 3}/ZrO{sub 2} exhibited obviously better ammonia oxidation performance compared with Pt/ZrO{sub 2}, the light-off temperature of NH{sub 3} shifted from 284 °C to 249 °C, the activation energy decreased from 113.4 kJ mol{sup −1} to 96.2 kJ mol{sup −1}.

  3. Process for catalytic flue gas denoxing

    International Nuclear Information System (INIS)

    Woldhuis, A.; Goudriaan, F.; Groeneveld, M.; Samson, R.

    1991-01-01

    With the increasing concern for the environment, stringency of legislation and industry's awareness of its own environmental responsibility, the demand for the reduction of emission levels of nitrogen oxides is becoming increasingly urgent. This paper reports that Shell has developed a low temperature catalytic deNOx system for deep removal of nitrogen oxides, which includes a low-pressure-drop reactor. This process is able to achieve over 90% removal of nitrogen oxides and therefore can be expected to meet legislation requirements for the coming years. The development of a low-temperature catalyst makes it possible to operate at temperatures as low as 120 degrees C, compared to 300-400 degrees C for the conventional honeycomb and plate-type catalysts. This allows an add-on construction, which is most often a more economical solution than the retrofits in the hot section required with conventional deNOx catalysts. The Lateral Flow Reactor (LFR), which is used for dust-free flue gas applications, and the Parallel Passage Reactor (PPR) for dust-containing flue gas applications, have been developed to work with pressure drops below 10 mbar

  4. The effect of temperature on the catalytic conversion of Kraft lignin using near-critical water

    DEFF Research Database (Denmark)

    Nguyen, Thi Dieu Huyen; Maschietti, Marco; Åmand, Lars-Erik

    2014-01-01

    The catalytic conversion of suspended LignoBoost Kraft lignin was performed in near-critical water using ZrO2/K2CO3 as the catalytic system and phenol as the co-solvent and char suppressing agent. The reaction temperature was varied from 290 to 370 C and its effect on the process was investigated...... in a continuous flow (1 kg/h). The yields of water-soluble organics (WSO), bio-oil and char (dry lignin basis) were in the ranges of 5–11%, 69–87% and 16–22%, respectively. The bio-oil, being partially deoxygenated, exhibited higher carbon content and heat value, but lower sulphur content than lignin. The main 1...

  5. Facile synthesis of PbTiO3 truncated octahedra via solid-state reaction and their application in low-temperature CO oxidation by loading Pt nanoparticles

    KAUST Repository

    Yin, Simin; Zhu, Yihan; Ren, Zhaohui; Chao, Chunying; Li, Xiang; Wei, Xiao; Shen, Ge; Han, Yu; Han, Gaorong

    2014-01-01

    Perovskite PbTiO3 (PTO) nanocrystals with a truncated octahedral morphology have been prepared by a facile solid-state reaction. Pt nanoparticles preferentially nucleated on the {111} facet of PTO nanocrystals exhibit a remarkable low-temperature catalytic activity towards CO oxidation from a temperature as low as 30 °C and achieve 100% conversion at ∼50 °C. © 2014 the Partner Organisations.

  6. COMPARISON OF WEST GERMAN AND U.S. FLUE GAS DESULFURIZATION AND SELECTIVE CATALYTIC REDUCTION COSTS

    Science.gov (United States)

    The report documents a comparison of the actual cost retrofitting flue gas desulfurization (FGD) and selective catalytic reduction (SCR) on Federal Republic of German (FRG) boilers to cost estimating procedures used in the U.S. to estimate the retrofit of these controls on U.S. b...

  7. Postmortem magnetic resonance imaging dealing with low temperature objects

    International Nuclear Information System (INIS)

    Kobayashi, Tomoya; Shiotani, Seiji; Isobe, Tomonori

    2010-01-01

    In Japan, the medical examiner system is not widespread, the rate of autopsy is low, and many medical institutions therefore perform postmortem imaging using clinical equipment. Postmortem imaging is performed to clarify cause of death, select candidates for autopsy, make a guide map for autopsy, or provide additional information for autopsy. Findings are classified into 3 categories: cause of death and associated changes, changes induced by cardiopulmonary resuscitation, and postmortem changes. Postmortem magnetic resonance imaging shows characteristic changes in signal intensity related to low body temperature after death; they are low temperature images. (author)

  8. Metal-Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles.

    Science.gov (United States)

    Lambert, Kyle M; Bobbitt, James M; Eldirany, Sherif A; Kissane, Liam E; Sheridan, Rose K; Stempel, Zachary D; Sternberg, Francis H; Bailey, William F

    2016-04-04

    Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98% isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Endurance and failure of an alumina-based monopropellant microthruster with integrated heater, catalytic bed and temperature sensors

    Science.gov (United States)

    Khaji, Zahra; Klintberg, Lena; Barbade, Dhananjay; Palmer, Kristoffer; Thornell, Greger

    2017-05-01

    Monopropellant ceramic microthrusters with an integrated heater, catalytic bed and two temperature sensors, but of various designs, were manufactured by milling a fluidic channel and chamber, and a nozzle, and screen printing platinum patterns on green tapes of alumina that were stacked and laminated before sintering. In order to increase the surface area of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, to leave behind a porous and rough layer. As an early development level in manufacturing robust and high-temperature tolerant microthrusters, the influence of design on the temperature gradients and dry temperature tolerance of the devices was studied. On average, the small reaction chambers showed a more than 1.5 times higher dry temperature tolerance (in centigrade) compared to devices with larger chambers, independent of the heater and device size. However, for a given temperature, big devices consumed on average 2.9 times more power than the small ones. It was also found that over the same area and under the same heating conditions, devices with small chambers were subjected to approximately 40% smaller temperature differences. A pressure test done on two small devices with small chambers revealed that pressures of at least 26.3 bar could be tolerated. Above this pressure, the interfaces failed but the devices were not damaged. To investigate the cooling effect of the micropropellant, the endurance of a full thruster was also studied under wet testing where it was fed with 31 wt.% hydrogen peroxide. The thruster demonstrated complete evaporation and/or full decomposition at a power above 3.7 W for a propellant flow of 50 µl min-1. At this power, the catalytic bed locally reached a temperature of 147 °C. The component was successfully heated to an operating temperature of 307 °C, where it cracked. Under these firing conditions, and assuming complete decomposition, calculations give a thrust and

  10. On the nanostructuring and catalytic promotion of intermediate temperature solid oxide fuel cell (IT-SOFC) cathodes

    Science.gov (United States)

    Serra, José M.; Buchkremer, Hans-Peter

    Solid oxide fuel cells (SOFCs) are highly efficient energy converters for both stationary and mobile purposes. However, their market introduction still demands the reduction of manufacture costs and one possible way to reach this goal is the decrease of the operating temperatures, which entails the improvement of the cathode electrocatalytic properties. An ideal cathode material may have mixed ionic and electronic conductivity as well as proper catalytic properties. Nanostructuring and catalytic promotion of mixed conducting perovskites (e.g. La 0.58Sr 0.4Fe 0.8Co 0.2O 3- δ) seem to be promising approaches to overcoming cathode polarization problems and are briefly illustrated here. The preparation of nanostructured cathodes with relatively high surface area and enough thermal stability enables to improve the oxygen exchange rate and therefore the overall SOFC performance. A similar effect was obtained by catalytic promoting the perovskite surface, allowing decoupling the catalytic and ionic-transport properties in the cathode design. Noble metal incorporation may improve the reversibility of the reduction cycles involved in the oxygen reduction. Under the cathode oxidizing conditions, Pd seems to be partially dissolved in the perovskite structure and as a result very well dispersed.

  11. Catalytic oxidative pyrolysis of spent organic ion exchange resins from nuclear power plants

    International Nuclear Information System (INIS)

    Sathi Sasidharan, N.; Deshingkar, D.S.; Wattal, P.K.; Shirsat, A.N.; Bharadwaj, S.R.

    2005-08-01

    The spent IX resins from nuclear power reactors are highly active solid wastes generated during operations of nuclear reactors. Catalytic oxidative pyrolysis of these resins can lead to high volume reduction of these wastes. Low temperature pyrolysis of transition metal ion loaded IX resins in presence of nitrogen was carried out in order to optimize catalyst composition to achieve maximum weight reduction. Thermo gravimetric analysis of the pyrolysis residues was carried out in presence of air in order to compare the oxidative characteristics of transition metal oxide catalysts. Copper along with iron, chromium and nickel present in the spent IX resins gave the most efficient catalyst combination for catalytic and oxidative pyrolysis of the residues. During low temperature catalytic pyrolysis, 137 Cesium volatility was estimated to be around 0.01% from cationic resins and around 0.1% from anionic resins. During oxidative pyrolysis at 700 degC, nearly 10 to 40% of 137 Cesium was found to be released to off gases depending upon type of resin and catalyst loaded on to it. The oxidation of pyrolytic residues at 700 degC gave weight reduction of 15% for cationic resins and 93% for anionic resins. Catalytic oxidative pyrolysis is attractive for reducing weight and volume of spent cationic resins from PHWRs and VVERs. (author)

  12. Catalytic oxidation for treatment of ECLSS and PMMS waste streams. [Process Material Management Systems

    Science.gov (United States)

    Akse, James R.; Thompson, John; Scott, Bryan; Jolly, Clifford; Carter, Donald L.

    1992-01-01

    Catalytic oxidation was added to the baseline multifiltration technology for use on the Space Station Freedom in order to convert low-molecular weight organic waste components such as alcohols, aldehydes, ketones, amides, and thiocarbamides to CO2 at low temperature (121 C), thereby reducing the total organic carbon (TOC) to below 500 ppb. The rate of reaction for the catalytic oxidation of aqueous organics to CO2 and water depends primarily upon the catalyst, temperature, and concentration of reactants. This paper describes a kinetic study conducted to determine the impact of each of these parameters upon the reaction rate. The results indicate that a classic kinetic model, the Langmuir-Hinshelwood rate equation for heterogeneous catalysis, can accurately represent the functional dependencies of this rate.

  13. Surface-Bound Intermediates in Low-Temperature Methanol Synthesis on Copper. Participants and Spectators

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong; Mei, Donghai; Peden, Charles HF; Campbell, Charles T.; Mims, Charles A.

    2015-11-03

    The reactivity of surface adsorbed species present on copper catalysts during methanol synthesis at low temperatures was studied by simultaneous infrared spectroscopy (IR) and mass spectroscopy (MS) measurements during “titration” (transient surface reaction) experiments with isotopic tracing. The results show that adsorbed formate is a major bystander species present on the surface under steady-state methanol synthesis reaction conditions, but it cannot be converted to methanol by reaction with pure H2, nor with H2 plus added water. Formate-containing surface adlayers for these experiments were produced during steady state catalysis in (a) H2:CO2 (with substantial formate coverage) and (b) moist H2:CO (with no IR visible formate species). Both these reaction conditions produce methanol at steady state with relatively high rates. Adlayers containing formate were also produced by (c) formic acid adsorption. Various "titration" gases were used to probe these adlayers at modest temperatures (T = 410-450K) and 6 bar total pressure. Methanol gas (up to ~1% monolayer equivalent) was produced in "titration" from the H2:CO2 catalytic adlayers by H2 plus water, but not by dry hydrogen. The decay in the formate IR features accelerated in the presence of added water vapor. The H2:CO:H2O catalytic adlayer produced similar methanol titration yields in H2 plus water but showed no surface formate features in IR (less than 0.2% monolayer coverage). Finally, formate from formic acid chemisorption produced no methanol under any titration conditions. Even under (H2:CO2) catalytic reaction conditions, isotope tracing showed that pre-adsorbed formate from formic acid did not contribute to the methanol produced. Although non-formate intermediates exist during low temperature methanol synthesis on copper which can be converted to methanol gas

  14. Selective catalytic reduction system and process using a pre-sulfated zirconia binder

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A.

    2010-06-29

    A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO.sub.2)SO.sub.4, palladium, and a pre-sulfated zirconia binder. The inclusion of a pre-sulfated zirconia binder substantially increases the durability of a Pd-based SCR catalyst system. A system for implementing the disclosed process is further provided.

  15. Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

    International Nuclear Information System (INIS)

    Qiu Lingguang; Gu Lina; Hu Gang; Zhang Lide

    2009-01-01

    Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen) 2 (H 2 O) 2 ] 2+ (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M 1 (H 2 O) 6 ].[M 2 (phen) 2 (H 2 O) 2 ] 2 .2(BTC).xH 2 O (M 1 , M 2 =Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22-24), were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed. - Grapical abstract: A modular design strategy has been developed to synthesize microporous metal-organic frameworks with potential catalytic activity by self-assembly of the framework-building blocks and the catalyst unit

  16. SSZ-13-supported manganese oxide catalysts for low temperature ...

    Indian Academy of Sciences (India)

    YONGZHOU YE

    Their performances for the selective catalytic reduction (SCR) of NOx with NH3 were evaluated. ... catalysts have received considerable attention.2,3 More- over, catalysts ..... zeolite channels or causing agglomeration on the cat- alyst surface ...

  17. Efficient Hydrogenolysis of Alkanes at Low Temperature and Pressure Using Tantalum Hydride on MCM-41, and a Quantum Chemical Study

    KAUST Repository

    Polshettiwar, Vivek; Pasha, Farhan Ahmad; De Mallmann, Aimery; Norsic, Sé bastien; Thivolle-Cazat, Jean; Basset, Jean-Marie

    2012-01-01

    Hydrogenolysis of hydrocarbons is of considerable technological importance for applications such as the hydroprocessing of petrochemical feedstocks to generate high-value and useful chemicals and fuels. We studied the catalytic activity of tantalum hydride supported on MCM-41 for the hydrogenolysis of alkanes at low temperature and low atmospheric pressure in a dynamic reactor. The reactions proceed with good turnover numbers, and the catalyst could be reused for several times, which makes the overall catalytic process sustainable. We derived the plausible mechanism by using DFT calculations and identified the preferred pathways by the analysis of potential energy surface. Our results and the proposed reaction mechanism demonstrate the viability of the "catalyst-by-design" approach. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Efficient Hydrogenolysis of Alkanes at Low Temperature and Pressure Using Tantalum Hydride on MCM-41, and a Quantum Chemical Study

    KAUST Repository

    Polshettiwar, Vivek

    2012-02-10

    Hydrogenolysis of hydrocarbons is of considerable technological importance for applications such as the hydroprocessing of petrochemical feedstocks to generate high-value and useful chemicals and fuels. We studied the catalytic activity of tantalum hydride supported on MCM-41 for the hydrogenolysis of alkanes at low temperature and low atmospheric pressure in a dynamic reactor. The reactions proceed with good turnover numbers, and the catalyst could be reused for several times, which makes the overall catalytic process sustainable. We derived the plausible mechanism by using DFT calculations and identified the preferred pathways by the analysis of potential energy surface. Our results and the proposed reaction mechanism demonstrate the viability of the "catalyst-by-design" approach. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis, spectroscopic characterization and catalytic oxidation ...

    Indian Academy of Sciences (India)

    were characterized by infrared, electronic, electron paramagnetic resonance ... The catalytic oxidation property of ruthenium(III) complexes were also ... cies at room temperature. ..... aldehyde part of Schiff base ligands, catalytic activ- ity of new ...

  20. Dynamic modeling of a three-stage low-temperature ethanol reformer for fuel cell application

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Vanesa M; Serra, Maria [Institut de Robotica i Informatica Industrial (CSIC-UPC), Llorens i Artigas 4-6, 08028 Barcelona (Spain); Lopez, Eduardo; Llorca, Jordi [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, ed. ETSEIB, 08028 Barcelona (Spain)

    2009-07-01

    A low-temperature ethanol reformer based on a cobalt catalyst for the production of hydrogen has been designed aiming the feed of a fuel cell for an autonomous low-scale power production unit. The reformer comprises three stages: ethanol dehydrogenation to acetaldehyde and hydrogen over SnO{sub 2} followed by acetaldehyde steam reforming over Co(Fe)/ZnO catalyst and water gas shift reaction. Kinetic data have been obtained under different experimental conditions and a dynamic model has been developed for a tubular reformer loaded with catalytic monoliths for the production of the hydrogen required to feed a 1 kW PEMFC. (author)

  1. On the Interpretation of Low Temperature Calorimetry Data

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2008-01-01

    The effect of selected factors and phenomena on Low Temperature Calorimetry (LTC) results has been investigated, in order to determine the possibilities and limitations of using LTC for characterisation of the porosity of cement-based materials. LTC was carried out on a model material with mono......-sized pores of approximately 14 nm saturated with either distilled water or a sodium chloride solution, as well as on water, the salt solution, and an artificial pore solution, alone. It was found that supercooling is unavoidable during the liquid-solid phase transition, and that even at low temperature...... to limit transport of liquid, whereas heating should be undertaken at a low rate to limit the effect of non-equilibrium....

  2. A Mesopore-Dependent Catalytic Cracking of n-Hexane Over Mesoporous Nanostructured ZSM-5.

    Science.gov (United States)

    Qamar, M; Ahmed, M I; Qamaruddin, M; Asif, M; Sanhoob, M; Muraza, O; Khan, M Y

    2018-08-01

    Herein, pore size, crystalinity, and Si/Al ratio of mesoporous ZSM-5 (MFI) nanocrystals was controlled by synthesis parameters, such as surfactant concentration ([3-(trimethoxysilyl)propyl] hexa-decyl dimethyl ammonium chloride), sodium hydroxide concentrations, synthesis temperature and time. The morphology, surface structure and composition of the MFI particles was systematically investigated. More notably, the mesopore-dependent catalytic activity of ZSM-5 was evaluated by studying the cracking of n-hexane. The findings suggest the porosity has pronounced impact on the catalytic activity, selectivity and stability of ZSM-5 nanocrystals. Critical surface attributes such as nature of acid sites (Brønsted and Lewis), concentration, and strength are obtained by the infrared study of adsorbed probe molecules (pyridine) and the temperature programmed desorption. In spite of being weaker in Si/Al ratio or acidic strength, mesoporous catalysts showed more stable and efficient cracking of n-hexane suggesting that acidity seems not the predominant factor operative in the activity, selectivity and stability.

  3. Catalytic properties and acidity of modified MCM-41 mesoporous materials with low Si/Al ratio: heptane isomerisation

    Directory of Open Access Journals (Sweden)

    Ahmed Belhakem

    2006-06-01

    Full Text Available The catalytic properties and acidity of modified MCM-41 with a low Si/Al ratio and 0-95% NH4+ exchange were investigated. The samples were characterised by X-ray diffraction, scanning and transmission electron microscopy, and nitrogen adsorption. The acidity was studied by pyridine adsorption, temperature programmed desorption (TPD of ammonia, and infrared (IR spectroscopy. Adsorption of pyridine and IR spectroscopy indicated various types of Lewis and Brönsted acid sites. The density distribution of acid sites was determined by TPD. Both Lewis and Brönsted acid sites were found to be active in the heptane isomerisation. The presence of aluminium (low Si/Al combined to the ionic exchange between Na+ and NH4+ increases the acidity of MCM-41 materials. A close correlation between acidity and isomerisation was observed. Coke deposition, which reduces the activity, was also studied.

  4. In-reactor stress relaxation of selected metals and alloys at low temperatures

    International Nuclear Information System (INIS)

    Causey, A.R.; Carpenter, G.J.C.; MacEwen, S.R.

    1980-01-01

    Stress relaxation of bent beam specimens under fast neutron irradiation at 340 and 570 K has been studied for a range of materials, as follows: several stainless steels, a maraged steel, AISI-4140, Ni, Inconel X-750, Ti, Zircaloy-2, Zr-2.5% Nb and Zr 3 Al. All specimens were in the annealed or solution-treated condition. Where comparisons were possible, the creep coefficients derived from the stress relaxation tests were found to be consistent with other studies of irradiation-induced creep. The steels showed the lowest rates of stress relaxation; the largest rates were observed with Zr-Nb, Ti and Ni. For most materials, the creep coefficient at 340 K was equal to or greater than that at 570 K. Such weak temperature dependence is not easily reconciled with existing models of irradiation creep based on dislocation climb, such as SIPA or climb-induced glide. Rate theory calculations indicate that because the vacancy mobility becomes very low at the lower temperature, recombination should dominate point defect annealing, resulting in a very low creep rate compared to that at the higher temperature. It is shown that the weak temperature dependence observed experimentally cannot be accounted for by the inclusion of more mobile divacancies in the calculation. (orig.)

  5. In-reactor stress relaxation of selected metals and alloys at low temperatures

    International Nuclear Information System (INIS)

    Causey, A.R.; Carpenter, G.J.C.; MacEwen, S.R.

    1980-01-01

    Stress relaxation of bent beam specimens under fast neutron irradiation at 340 and 570 K has been studied for a range of materials, as follows: several stainless steels, a maraged steel, AISI-4140, Ni, Inconel X-750, Ti, Zircaloy-2, Zr-2.5% Nb and Zr 3 A1. All specimens were in the annealed or solution-treated condition. Where comparisons were possible, the creep coefficients derived from the stress relaxation tests were found to be consistent with other studies of irradiation-induced creep. The steels showed the lowest rates of stress relaxation; the largest rates were observed with Zr-Nb, Ti and Ni. For most materials, the creep coefficient at 340 K was equal to or greater than that at 570 K. Such weak temperature dependence is not easily reconciled with existing models of irradiation creep based on dislocation climb, such as SIPA or climb-induced glide. Rate theory calculations indicate that because the vacancy mobility becomes very low at the lower temperature, recombination should dominate point defect annealing, resulting in a very low creep rate compared to that at the higher temperature. It is shown that the weak temperature dependence observed experimentally cannot be accounted for by the inclusion of more mobile divacancies in the calculation. (author)

  6. Uniformity index measurement technology using thermocouples to improve performance in urea-selective catalytic reduction systems

    Science.gov (United States)

    Park, Sangki; Oh, Jungmo

    2018-05-01

    The current commonly used nitrogen oxides (NOx) emission reduction techniques employ hydrocarbons (HCs), urea solutions, and exhaust gas emissions as the reductants. Two of the primary denitrification NOx (DeNOx) catalyst systems are the HC-lean NOx trap (HC-LNT) catalyst and urea-selective catalytic reduction (urea-SCR) catalyst. The secondary injection method depends on the type of injector, injection pressure, atomization, and spraying technique. In addition, the catalyst reaction efficiency is directly affected by the distribution of injectors; hence, the uniformity index (UI) of the reductant is very important and is the basis for system optimization. The UI of the reductant is an indicator of the NOx conversion efficiency (NCE), and good UI values can reduce the need for a catalyst. Therefore, improving the UI can reduce the cost of producing a catalytic converter, which are expensive due to the high prices of the precious metals contained therein. Accordingly, measurement of the UI is an important process in the development of catalytic systems. Two of the commonly used methods for measuring the reductant UI are (i) measuring the exhaust emissions at many points located upstream/downstream of the catalytic converter and (ii) acquisition of a reductant distribution image on a section of the exhaust pipe upstream of the catalytic converter. The purpose of this study is to develop a system and measurement algorithms to measure the exothermic response distribution in the exhaust gas as the reductant passes through the catalytic converter of the SCR catalyst system using a set of thermocouples downstream of the SCR catalyst. The system is used to measure the reductant UI, which is applied in real-time to the actual SCR system, and the results are compared for various types of mixtures for various engine operating conditions and mixer types in terms of NCE.

  7. Synthesis of ultrasmall Li-Mn spinel oxides exhibiting unusual ion exchange, electrochemical, and catalytic properties

    Science.gov (United States)

    Miyamoto, Yumi; Kuroda, Yoshiyuki; Uematsu, Tsubasa; Oshikawa, Hiroyuki; Shibata, Naoya; Ikuhara, Yuichi; Suzuki, Kosuke; Hibino, Mitsuhiro; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-10-01

    The efficient surface reaction and rapid ion diffusion of nanocrystalline metal oxides have prompted considerable research interest for the development of high functional materials. Herein, we present a novel low-temperature method to synthesize ultrasmall nanocrystalline spinel oxides by controlling the hydration of coexisting metal cations in an organic solvent. This method selectively led to Li-Mn spinel oxides by tuning the hydration of Li+ ions under mild reaction conditions (i.e., low temperature and short reaction time). These particles exhibited an ultrasmall crystallite size of 2.3 nm and a large specific surface area of 371 ± 15 m2 g-1. They exhibited unique properties such as unusual topotactic Li+/H+ ion exchange, high-rate discharge ability, and high catalytic performance for several aerobic oxidation reactions, by creating surface phenomena throughout the particles. These properties differed significantly from those of Li-Mn spinel oxides obtained by conventional solid-state methods.

  8. Synthesis of ultrasmall Li–Mn spinel oxides exhibiting unusual ion exchange, electrochemical, and catalytic properties

    Science.gov (United States)

    Miyamoto, Yumi; Kuroda, Yoshiyuki; Uematsu, Tsubasa; Oshikawa, Hiroyuki; Shibata, Naoya; Ikuhara, Yuichi; Suzuki, Kosuke; Hibino, Mitsuhiro; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-01-01

    The efficient surface reaction and rapid ion diffusion of nanocrystalline metal oxides have prompted considerable research interest for the development of high functional materials. Herein, we present a novel low-temperature method to synthesize ultrasmall nanocrystalline spinel oxides by controlling the hydration of coexisting metal cations in an organic solvent. This method selectively led to Li–Mn spinel oxides by tuning the hydration of Li+ ions under mild reaction conditions (i.e., low temperature and short reaction time). These particles exhibited an ultrasmall crystallite size of 2.3 nm and a large specific surface area of 371 ± 15 m2 g−1. They exhibited unique properties such as unusual topotactic Li+/H+ ion exchange, high-rate discharge ability, and high catalytic performance for several aerobic oxidation reactions, by creating surface phenomena throughout the particles. These properties differed significantly from those of Li–Mn spinel oxides obtained by conventional solid-state methods. PMID:26456216

  9. Low-temperature graphene synthesis using microwave plasma CVD

    International Nuclear Information System (INIS)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-01-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 10 5 Ω/sq.

  10. Low-temperature graphene synthesis using microwave plasma CVD

    Science.gov (United States)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-02-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

  11. Microwave-Assisted Selective Hydrogenation of Furfural to Furfuryl Alcohol Employing a Green and Noble Metal-Free Copper Catalyst.

    Science.gov (United States)

    Romano, Pedro N; de Almeida, João M A R; Carvalho, Yuri; Priecel, Peter; Falabella Sousa-Aguiar, Eduardo; Lopez-Sanchez, Jose A

    2016-12-20

    Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H 2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3-4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass-derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fluid selection for a low-temperature solar organic Rankine cycle

    International Nuclear Information System (INIS)

    Tchanche, Bertrand Fankam; Papadakis, George; Lambrinos, Gregory; Frangoudakis, Antonios

    2009-01-01

    Theoretical performances as well as thermodynamic and environmental properties of few fluids have been comparatively assessed for use in low-temperature solar organic Rankine cycle systems. Efficiencies, volume flow rate, mass flow rate, pressure ratio, toxicity, flammability, ODP and GWP were used for comparison. Of 20 fluids investigated, R134a appears as the most suitable for small scale solar applications. R152a, R600a, R600 and R290 offer attractive performances but need safety precautions, owing to their flammability.

  13. Catalytic reforming of glycerol in supercritical water over bimetallic Pt-Ni catalyst

    NARCIS (Netherlands)

    Chakinala, A.G.; van Swaaij, Willibrordus Petrus Maria; Kersten, Sascha R.A.; de Vlieger, Dennis; Seshan, Kulathuiyer; Brilman, Derk Willem Frederik

    2013-01-01

    Catalytic reforming of pure glycerol for the production of hydrogen at low temperature and short residence times in supercritical water was investigated using a bimetallic Pt–Ni catalyst supported on alumina. Initial tests were carried out to study the reforming activity of bimetallic Pt–Ni

  14. Low-Temperature Synthesis Routes to Intermetallic Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schaak, Raymond E

    2008-01-08

    Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies

  15. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion

    International Nuclear Information System (INIS)

    Pozan, Gulin Selda

    2012-01-01

    Highlights: ► α-Al 2 O 3 , obtained from Bohmite, as a support for enhancing of the activity. ► The support material for catalytic oxidation. ► The manganese state and oxygen species effect on the catalytic combustion reaction. - Abstract: The aim of this work was to study combustion of toluene (1000 ppm) over MnO 2 modified with different supports. α-Al 2 O 3 and γ-Al 2 O 3 obtained from Boehmite, γ-Al 2 O 3 (commercial), SiO 2 , TiO 2 and ZrO 2 were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO 2 was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO 2 /α-Al 2 O 3 (B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289 °C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity.

  16. Catalytic dehydration of ethanol to ethylene over HMOR HZSM-5 modified with copper and iron

    Directory of Open Access Journals (Sweden)

    José Luis Agudelo

    2005-09-01

    Full Text Available Catalytic dehydration of ethanol to ethylene on HMOR (Si/Al = 6.5, HZSM-5 (Si/Al = 29, Cu-HZSM-5 (Si/Al = 98 and Fe-HZSM-5 (Si/Al = 151 was studied at atmospheric pressure and 120oC - 300ºC. ZSM-5 supported catalysts were active at temperatures over 260ºC, achieving more than 60% conversion. Ethylene was predominantly produced as a dehydration product. Incorporating Cu did not significantly improve catalytic activity compared to HZSM-5. H-MOR was very active at low temperatures but deactivated rapidly at 240ºC, most probably due to coke formation.

  17. Effect of calcination temperature on the structure and performance of CeO{sub x}–MnO{sub x}/TiO{sub 2} nanoparticles for the catalytic combustion of chlorobenzene

    Energy Technology Data Exchange (ETDEWEB)

    He, Fei; Chen, Yong; Zhao, Pei; Liu, Shantang, E-mail: anliu123@hotmail.com [Wuhan Institute of Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemistry and Environmental Engineering (China)

    2016-05-15

    In this study, MnO{sub x}/TiO{sub 2}, CeO{sub x}/TiO{sub 2}, and CeO{sub x}–MnO{sub x}/TiO{sub 2} catalysts were prepared by the homogeneous precipitation method. The effect of calcination temperature on the structure and catalytic performance of CeO{sub x}–MnO{sub x}/TiO{sub 2} mixed oxide catalyst in the catalytic combustion of chlorobenzene was investigated. The samples were characterized by X-ray diffraction, nitrogen adsorption–desorption, transmission electron microscopy, Raman spectra, hydrogen temperature-programmed reduction, and X-ray photoelectron spectroscopy. The results indicate that calcination significantly affect the activity of the prepared catalysts. When calcined at a low temperature such as 400 °C, Ce, and Mn species form a solid solution of MnCeO{sub x} in the catalyst, thus locating the O atoms in a perturbed chemical surrounding in the catalysts. This increases the mobility of the O atoms during the reaction, probably contributing to the highest catalytic activity of CeO{sub x}–MnO{sub x}/TiO{sub 2} among all the tested catalysts. However, a further increase in the calcination temperature decreased the performance of the catalyst for the catalytic combustion of chlorobenzene. This is probably because of a reduction in surface chemisorbed oxygen concentration, a decrease in the interface area between metal oxides and MnCeO{sub x} caused by the isolation of MnO{sub x} or CeO{sub 2} from MnCeO{sub x}, and a decrease in the specific surface area of CeO{sub x}–MnO{sub x}/TiO{sub 2} catalyst due to the sintering of catalyst.Graphical Abstract.

  18. Evaluation of catalytic combustion of actual coal-derived gas

    Science.gov (United States)

    Blanton, J. C.; Shisler, R. A.

    1982-01-01

    The combustion characteristics of a Pt-Pl catalytic reactor burning coal-derived, low-Btu gas were investigated. A large matrix of test conditions was explored involving variations in fuel/air inlet temperature and velocity, reactor pressure, and combustor exit temperature. Other data recorded included fuel gas composition, reactor temperatures, and exhaust emissions. Operating experience with the reactor was satisfactory. Combustion efficiencies were quite high (over 95 percent) over most of the operating range. Emissions of NOx were quite high (up to 500 ppm V and greater), owing to the high ammonia content of the fuel gas.

  19. Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon

    International Nuclear Information System (INIS)

    Rodriguez, Henry; Hoyos Bibian

    2004-01-01

    Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon was studied, in acid media at different temperatures and concentrations. During the maturation time of deposited iridium, the surface is covered by an irreversible oxide formation, which affects the behavior of the catalytic mixture. The Pt 7 0 Ir 3 0 and Pt 9 0 Ir 1 0 mixtures seem to be a little more active than the Pt/C electrode at potentials below 800 mV (vs. HRE). In all electrodes appears two reactions: partial ethanol oxidation to produce acetaldehyde (main path of reaction at low temperatures and high electrode coverage with ethanol adsorption residues) and the total oxidation to carbon dioxide which is considerable at potential above 800 mV and it is increased with increasing temperature

  20. Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation

    KAUST Repository

    Imran, Ali; Bramer, Eddy; Seshan, Kulathuiyer; Brem, Gerrit

    2016-01-01

    -staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low

  1. Low-temperature conversion of high-moisture biomass: Topical report, January 1984--January 1988

    Energy Technology Data Exchange (ETDEWEB)

    Sealock, L.J. Jr.; Elliott, D.C.; Butner, R.S.; Neuenschwander, G.G.

    1988-10-01

    Pacific Northwest Laboratory (PNL) is developing a low-temperature, catalytic process that converts high-moisture biomass feedstocks and other wet organic substances to useful gaseous and liquid fuels. The advantage of this process is that it works without the need for drying or dewatering the feedstock. Conventional thermal gasification processes, which require temperatures above 750/degree/C and air or oxygen for combustion to supply reaction heat, generally cannot utilize feedstocks with moisture contents above 50 wt %, as the conversion efficiency is greatly reduced as a result of the drying step. For this reason, anaerobic digestion or other bioconversion processes traditionally have been used for gasification of high-moisture feedstocks. However, these processes suffer from slow reaction rates and incomplete carbon conversion. 50 refs., 21 figs., 22 tabs.

  2. Catalytic-Dielectric Barrier Discharge Plasma Reactor For Methane and Carbon Dioxide Conversion

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2007-10-01

    Full Text Available A catalytic - DBD plasma reactor was designed and developed for co-generation of synthesis gas and C2+ hydrocarbons from methane. A hybrid Artificial Neural Network - Genetic Algorithm (ANN-GA was developed to model, simulate and optimize the reactor. Effects of CH4/CO2 feed ratio, total feed flow rate, discharge voltage and reactor wall temperature on the performance of catalytic DBD plasma reactor was explored. The Pareto optimal solutions and corresponding optimal operating parameters ranges based on multi-objectives can be suggested for catalytic DBD plasma reactor owing to two cases, i.e. simultaneous maximization of CH4 conversion and C2+ selectivity, and H2 selectivity and H2/CO ratio. It can be concluded that the hybrid catalytic DBD plasma reactor is potential for co-generation of synthesis gas and higher hydrocarbons from methane and carbon dioxide and showed better than the conventional fixed bed reactor with respect to CH4 conversion, C2+ yield and H2 selectivity for CO2 OCM process. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: I. Istadi, N.A.S. Amin. (2007. Catalytic-Dielectric Barrier Discharge Plasma Reactor For Methane and Carbon Dioxide Conversion. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 37-44.  doi:10.9767/bcrec.2.2-3.8.37-44][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.8.37-44 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/8][Cited by: Scopus 1 |

  3. Multi-Stage Selective Catalytic Reduction of NOx in Lean-Burn Engine Exhaust

    National Research Council Canada - National Science Library

    Penetrante, B

    1997-01-01

    .... A plasma can also be used to oxidize NO to NO2. This paper compares the multi-stage catalytic scheme with the plasma-assisted catalytic scheme for reduction of NOx in lean-burn engine exhausts. The advantages of plasma oxidation over catalytic oxidation are presented.

  4. Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

    KAUST Repository

    Hinkle, C. L.; Galatage, R. V.; Chapman, R. A.; Vogel, E. M.; Alshareef, Husam N.; Freeman, C.; Christensen, M.; Wimmer, E.; Niimi, H.; Li-Fatou, A.; Shaw, J. B.; Chambers, J. J.

    2012-01-01

    Silicon N-metal-oxide-semiconductor (NMOS) and P-metal-oxide-semiconductor (PMOS) band edge effective work functions and the correspondingly low threshold voltages (Vt) are demonstrated using standard fab materials and processes in a gate-last scheme employing low-temperature anneals and selective cladding layers. Al diffusion from the cladding to the TiN/HfO2interface during forming gas anneal together with low O concentration in the TiN enables low NMOS Vt. The use of non-migrating W cladding along with experimentally detected N-induced dipoles, produced by increased oxygen in the TiN, facilitates low PMOS Vt.

  5. Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

    KAUST Repository

    Hinkle, C. L.

    2012-04-09

    Silicon N-metal-oxide-semiconductor (NMOS) and P-metal-oxide-semiconductor (PMOS) band edge effective work functions and the correspondingly low threshold voltages (Vt) are demonstrated using standard fab materials and processes in a gate-last scheme employing low-temperature anneals and selective cladding layers. Al diffusion from the cladding to the TiN/HfO2interface during forming gas anneal together with low O concentration in the TiN enables low NMOS Vt. The use of non-migrating W cladding along with experimentally detected N-induced dipoles, produced by increased oxygen in the TiN, facilitates low PMOS Vt.

  6. Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.

    2007-07-01

    The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

  7. Catalytic generation of methane at 60-100 °C and 0.1-300 MPa from source rocks containing kerogen Types I, II, and III

    Science.gov (United States)

    Wei, Lin; Schimmelmann, Arndt; Mastalerz, Maria; Lahann, Richard W.; Sauer, Peter E.; Drobniak, Agnieszka; Strąpoć, Dariusz; Mango, Frank D.

    2018-06-01

    Low temperature (60 and 100 °C) and long-term (6 months to 5 years) heating of pre-evacuated and sterilized shales and coals containing kerogen Types I (Mahogany Shale), II (Mowry Shale and New Albany Shale), and III (Springfield Coal and Wilcox Lignite) with low initial maturities (vitrinite reflectance Ro 0.39-0.62%) demonstrates that catalytically generated hydrocarbons may explain the occurrence of some non-biogenic natural gas accumulations where insufficient thermal maturity contradicts the conventional thermal cracking paradigm. Extrapolation of the observed rate of catalytic methanogenesis in the laboratory suggests that significant amounts of sedimentary organic carbon can be converted to relatively dry natural gas over tens of thousands of years in sedimentary basins at temperatures as low as 60 °C. Our laboratory experiments utilized source rock (shale and coal) chips sealed in gold and Pyrex® glass tubes in the presence of hydrogen-isotopically contrasting waters. Parallel heating experiments applied hydrostatic pressures from 0.1 to 300 MPa. Control experiments constrained the influence of pre-existing and residual methane in closed pores of rock chips that was unrelated to newly generated methane. This study's experimental methane yields at 60 and 100 °C are 5-11 orders of magnitude higher than the theoretically predicted yields from kinetic models of thermogenic methane generation, which strongly suggests a contribution of catalytic methanogenesis. Higher temperature, longer heating time, and lower hydrostatic pressure enhanced catalytic methanogenesis. No clear relationships were observed between kerogen type or total organic carbon content and methane yields via catalysis. Catalytic methanogenesis was strongest in Mowry Shale where methane yields at 60 °C amounted to ∼2.5 μmol per gram of organic carbon after one year of hydrous heating at ambient pressure. In stark contrast to the earlier findings of hydrogen isotopic exchange between

  8. Effect of Dopant Loading on the Structural and Catalytic Properties of Mn-Doped SrTiO3 Catalysts for Catalytic Soot Combustion

    Directory of Open Access Journals (Sweden)

    Santiago Iván Suárez-Vázquez

    2018-02-01

    Full Text Available Soot particles have been associated with respiratory diseases and cancer. To decrease these emissions, perovskite-mixed oxides have been proposed due to their thermal stability and redox surface properties. In this work, SrTiO3 doped with different amounts of Mn were synthesized by the hydrothermal method and tested for soot combustion. Results show that at low Mn content, structural distortion, and higher Oads/Olat ratio were observed which was attributed to the high content of Mn3+ in Ti sites. On the other hand, increasing the Mn content led to surface segregation of manganese oxide. All synthesized catalysts showed mesopores in the range of 32–47 nm. In the catalytic combustion of soot, the samples synthesized in this work lowered the combustion temperature by more than 100 °C compared with the uncatalyzed reaction. The sample doped with 1 wt % of Mn showed the best catalytic activity. The activation energy of these samples was also calculated, and the order of decreasing activation energy is as follows: uncatalyzed > Mn0 > Mn8 > Mn4 > Mn1. The best catalytic activity for Mn1 was attributed to its physicochemical properties and the mobility of the oxygen from the bulk to the surface at temperatures higher than 500 °C.

  9. Pyroelectrically Induced Pyro-Electro-Chemical Catalytic Activity of BaTiO3 Nanofibers under Room-Temperature Cold–Hot Cycle Excitations

    OpenAIRE

    Yuntao Xia; Yanmin Jia; Weiqi Qian; Xiaoli Xu; Zheng Wu; Zichen Han; Yuanting Hong; Huilin You; Muhammad Ismail; Ge Bai; Liwei Wang

    2017-01-01

    A pyro-electro-chemical catalytic dye decomposition using lead-free BaTiO3 nanofibers was realized under room-temperature cold–hot cycle excitation (30–47 °C) with a high Rhodamine B (RhB) decomposition efficiency ~99%, which should be ascribed to the product of pyro-electric effect and electrochemical redox reaction. Furthermore, the existence of intermediate product of hydroxyl radical in pyro-electro-chemical catalytic process was also observed. There is no significant decrease in pyro-ele...

  10. Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol over Nitrogen-Doped Carbon-Supported Iron Catalysts.

    Science.gov (United States)

    Li, Jiang; Liu, Jun-Ling; Zhou, Hong-Jun; Fu, Yao

    2016-06-08

    Iron-based heterogeneous catalysts, which were generally prepared by pyrolysis of iron complexes on supports at elevated temperature, were found to be capable of catalyzing the transfer hydrogenation of furfural (FF) to furfuryl alcohol (FFA). The effects of metal precursor, nitrogen precursor, pyrolysis temperature, and support on catalytic performance were examined thoroughly, and a comprehensive study of the reaction parameters was also performed. The highest selectivity of FFA reached 83.0 % with a FF conversion of 91.6 % under the optimal reaction condition. Catalyst characterization suggested that iron cations coordinated by pyridinic nitrogen functionalities were responsible for the enhanced catalytic activity. The iron catalyst could be recycled without significant loss of catalytic activity for five runs, and the destruction of the nitrogen-iron species, the presence of crystallized Fe2 O3 phase, and the pore structure change were the main reasons for catalyst deactivation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    Directory of Open Access Journals (Sweden)

    Maciel Adeilton

    2008-01-01

    Full Text Available AbstractNanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  12. Preparation of Cu-Fe-Al-O nanosheets and their catalytic application in methanol steam reforming for hydrogen production

    Science.gov (United States)

    Wang, Leilei; Zhang, Fan; Miao, Dinghao; Zhang, Lei; Ren, Tiezhen; Hui, Xidong; He, Zhanbing

    2017-03-01

    Candidates of precious metal catalysts, prepared in a facile and environmental way and showing high catalytic performances at low temperatures, are always highly desired by industry. In this work, large-scale Cu-Fe-Al-O nanosheets were synthesized by facile dealloying of Al-Cu-Fe alloys in NaOH solution. The composition, microscopic morphology, and crystal structure were respectively investigated using wavelength-dispersive x-ray spectroscopy with an electron probe microanalyzer, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. Furthermore, we found that the 2D Cu-Fe-Al-O nanosheets gave excellent catalytic performances in hydrogen production by methanol steam reforming at relatively low temperatures, e.g. 513 K.

  13. Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

    Science.gov (United States)

    Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

    2014-03-01

    Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Morphology induced photo-degradation study of low temperature, chemically derived ZnO/SnO{sub 2} heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Shreyasi, E-mail: Shreyasi.tua@gamil.com; Maiti, Soumen; Chattopadhyay, Kalyan Kumar, E-mail: kalyan-chattopadhyay@yahoo.com [Thin Films and Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India)

    2016-05-06

    Rational construction of heterostructure is a key pathway to pursue highly active photocatalysts that also offers prospects to explore the relationship between structural aspect and photocatalytic efficiency. Here, we adopted a two-step wet chemical protocol for decoration of ZnO nanowires with SnO{sub 2} nanoclusters. ZnO nanowires were prepared by one pot ambient conditioned synthesis from commercial zinc powder. In sequence, synthesized ZnO nanowires were engineered with varying quantity SnO{sub 2} nanoclusters via low temperature hydrothermal method. Environmental remediation through catalytic activity of the samples was inspected taking two dyes having different ionic character (Methyl Orange and Rhodamine B) under UV irradiation where the optimized hybrid displayed better performance than mono component oxides. Enhancement in catalytic performance could be enlightened by the heterostructure formation at the ZnO/SnO{sub 2} interface which in turns prolonged photogenerated carrier separation and extend the photo response range. Furthermore, the photocatalysis performance by heterostructure could be recycled for several times without noticeable decrease in their catalytic activity.

  15. Synthesis and kinetics investigation of meso-microporous Cu-SAPO-34 catalysts for the selective catalytic reduction of NO with ammonia.

    Science.gov (United States)

    Liu, Jixing; Yu, Fuhong; Liu, Jian; Cui, Lifeng; Zhao, Zhen; Wei, Yuechang; Sun, Qianyao

    2016-10-01

    A series of meso-microporous Cu-SAPO-34 catalysts were successfully synthesized by a one-pot hydrothermal crystallization method, and these catalysts exhibited excellent NH 3 -SCR performance at low temperature. Their structure and physic chemical properties were characterized by means of X-ray diffraction patterns (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N 2 sorption-desorption, nuclear magnetic resonance (NMR), Inductively Coupled Plasma-Atomic Emission spectrometer (ICP-AES), X-ray absorption spectroscopy (XPS), Temperature-programmed desorption of ammonia (NH 3 -TPD), Ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS) and Temperature programmed reduction (TPR). The analysis results indicate that the high activities of Cu-SAPO-34 catalysts could be attributed to the enhancement of redox property, the formation of mesopores and the more acid sites. Furthermore, the kinetic results verify that the formation of mesopores remarkably reduces diffusion resistance and then improves the accessibility of reactants to catalytically active sites. The 1.0-Cu-SAPO-34 catalyst exhibited the high NO conversion (>90%) among the wide activity temperature window in the range of 150-425°C. Copyright © 2016. Published by Elsevier B.V.

  16. LASER INDUCED SELECTIVE ACTIVATION UTILIZING AUTO-CATALYTIC ELECTROLESS PLATING ON POLYMER SURFACE

    DEFF Research Database (Denmark)

    Zhang, Yang; Nielsen, Jakob Skov; Tang, Peter Torben

    2009-01-01

    . Characterization of the deposited copper layer was used to select and improve laser parameters. Several types of polymers with different melting points were used as substrate. Using the above mentioned laser treatment, standard grades of thermoplastic materials such as ABS, SAN, PE, PC and others have been......This paper presents a new method for selective micro metallization of polymers induced by laser. An Nd: YAG laser was employed to draw patterns on polymer surfaces using a special set-up. After subsequent activation and auto-catalytic electroless plating, copper only deposited on the laser tracks....... Induced by the laser, porous and rough structures are formed on the surface, which favours the palladium attachment during the activation step prior to the metallization. Laser focus detection, scanning electron microscopy (SEM) and other instruments were used to analyze the topography of the laser track...

  17. A fuzzy logic urea dosage controller design for two-cell selective catalytic reduction systems.

    Science.gov (United States)

    You, Kun; Wei, Lijiang; Jiang, Kai

    2017-12-22

    Diesel engines have dominated in the heavy-duty vehicular and marine power source. However, the induced air pollution is a big problem. As people's awareness of environmental protection increasing, the emission regulations of diesel-engine are becoming more stringent. In order to achieve the emission regulations, the after-treatment system is a necessary choice. Specifically, the selective catalytic reduction (SCR) system has been widely applied to reduce the NO X emissions of diesel engine. Different from single-cell SCR systems, the two-cell systems have various benefits from the modeling and control perspective. In this paper, the urea dosage controller design for two-cell SCR systems was investigated. Firstly, the two-cell SCR modeling was introduced. Based on the developed model, the design procedure for the fuzzy logic urea dosage controller was well addressed. Secondly, simulations and comparisons were employed via an experimental verification of the whole vehicle simulator. And the results showed that the designed controller simultaneously achieved high NO X reduction rate and low tail-pipe ammonia slip. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  18. Catalytic optimization and physicochemical studies over Zn/Ca/Al2O3 catalyst for transesterification of low grade cooking oil

    International Nuclear Information System (INIS)

    Mohd Kamal, Norhasyimah; Wan Abu Bakar, Wan Azelee; Ali, Rusmidah

    2017-01-01

    Highlights: • Zn/Ca/Al 2 O 3 has high potential in producing biodiesel. • High basicity favoured high conversion of biodiesel. • Calcination temperature showed the highest influence on the catalytic activity. • RSM was used to determine the optimum operating conditions for biodiesel production. - Abstract: Recently, there has been an increasing interest in green and renewable fuels due to the worldwide concern of an environmental crisis. So, this study focused on the synthesis, optimization and characterization of series of heterostructure Zn/Ca/Al 2 O 3 catalysts with different parameters to test their effectiveness towards biodiesel production. The physicochemical properties of the potential catalyst were determined by BET, FESEM and CO 2 -TPD. The activity of the catalyst in transesterification reaction was evaluated at reaction temperature of 65 °C, 3 h reaction time, 6% (w/w) catalyst concentration and 1:24 M ratio of oil to methanol. The investigation of the synthesized Zn/Ca/Al 2 O 3 catalyst showed that the calcination temperature, number of alumina coatings and dopant to base ratio have significant effects on the catalytic performance. These three critical parameters were investigated using response surface methodology (RSM) with Box Behnken design (BBD) to determine the optimum operating conditions for biodiesel production. From RSM study, the optimum conditions were 800 °C calcination temperature, 3 times alumina beads coating and 10:90 dopant to base ratio which gave 97.80% biodiesel conversion. From the F-value and low p-value (<0.05) obtained showed that the model was significant for predicting the optimum biodiesel conversion. An experiment was conducted under the optimum conditions to confirm the agreement of the model prediction and the experimental results. The experimental value (97.64%) closely agreed with the predicted results from RSM and hence validated the findings of response surface optimization.

  19. Catalytic reactor for low-Btu fuels

    Science.gov (United States)

    Smith, Lance; Etemad, Shahrokh; Karim, Hasan; Pfefferle, William C.

    2009-04-21

    An improved catalytic reactor includes a housing having a plate positioned therein defining a first zone and a second zone, and a plurality of conduits fabricated from a heat conducting material and adapted for conducting a fluid therethrough. The conduits are positioned within the housing such that the conduit exterior surfaces and the housing interior surface within the second zone define a first flow path while the conduit interior surfaces define a second flow path through the second zone and not in fluid communication with the first flow path. The conduit exits define a second flow path exit, the conduit exits and the first flow path exit being proximately located and interspersed. The conduits define at least one expanded section that contacts adjacent conduits thereby spacing the conduits within the second zone and forming first flow path exit flow orifices having an aggregate exit area greater than a defined percent of the housing exit plane area. Lastly, at least a portion of the first flow path defines a catalytically active surface.

  20. Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags : the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique

    NARCIS (Netherlands)

    Sanchez-Romaquera, V.; Wïnscher, S.; Turki, B.M.; Abbel, R.J.; Barbosa, S.; Tate, D.J.; Oyeka, D.; Batchelor, J.C.; Parker, E.A.; Schubert, U.S.; Yeates, S.G.

    2015-01-01

    Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices

  1. Low temperature incineration of mixed wastes using bulk metal oxide catalysts

    International Nuclear Information System (INIS)

    Gordon, M.J.; Gaur, S.; Kelkar, S.; Baldwin, R.M.

    1996-01-01

    Volume reduction of low-level mixed wastes from former nuclear weapons facilities is a significant environmental problem. Processing of these materials presents unique scientific and engineering problems due to the presence of minute quantities of radionuclides which must be contained and concentrated for later safe disposal. Low-temperature catalytic incineration is one option that has been utilized at the Rocky Flats facility for this purpose. This paper presents results of research regarding evaluation of bulk metal oxides as catalysts for low-temperature incineration of carbonaceous residues which are typical by-products of fluidized bed combustion of mixed wastes under oxygen-lean conditions. A series of 14 metal oxides were screened in a thermogravimetric analyzer, using on-line mass spectrometry for speciation of reaction product gases. Catalyst evaluation criteria focused on the thermal-redox activity of the metals using both carbon black and PVC char as surrogate waste materials. Results indicated that metal oxides which were P-type semiconductor materials were suitable as catalysts for this application. Oxides of cobalt, molybdenum, vanadium, and manganese were found to be particularly stable and active catalysts under conditions specific to this process (T<650C, low oxygen partial pressures). Bench-scale evaluation of these metal oxides with respect to stability to chlorine (HCl) attack was carried out at 550C using a TG/MS system. Cobalt oxide was found to be resistant to metal loss in a HCl/He gaseous environment while metal loss from Mo, Mn, and V-based catalysts was moderate to severe. XRD and SEM/EDX analysis of spent Co catalysts indicated the formation of non-stoichiometric cobalt chlorides. Regeneration of chlorinated cobalt was found to successfully restore the low-temperature combustion activity to that of the fresh metal oxide

  2. Synthesis and microstructure of La_1_−_xCa_xCoO_3 nanoparticles and their catalytic activity for CO oxidation

    International Nuclear Information System (INIS)

    Luu, Tien Hung; Nguyen, Xuan Dung; Phan, Thi Minh Huyen; Schulze, Steffen; Hietschold, Michael

    2015-01-01

    Perovskite nanoparticles of La_1_−_xCa_xCoO_3 (x = 0, 0.2, 0.3, 0.5) were synthesized by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. Microstructure of samples was characterized by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) combined with x-ray diffraction (XRD). The nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and BET (Brunauer–Emmet–Teller). A high surface area (15–21 m"2 g"−"1) at low temperature (600 °C) of samples was obtained. The optimal preparative conditions were PVA/metals 2:1 by mole, pH = 3 and 80 °C for gel formation. Perovskites exhibit a good catalytic activity in total oxidation of CO at the low temperature (<250 °C) of reaction. (paper)

  3. Halogen poisoning effect of Pt-TiO{sub 2} for formaldehyde catalytic oxidation performance at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaofeng; Cheng, Bei [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Tai Po, N.T. Hong Kong (China)

    2016-02-28

    Graphical abstract: - Highlights: • The Pt-TiO{sub 2} catalyst is deactivated by adsorption of halogen ions. • The halogen poison is mainly attributed to the active site blocking of the Pt surface. • Halogen ions and Pt form Pt−X coordination bonds. • Large halogen diameter exhibits severe poisoning effect. - Abstract: Catalytic decomposition of formaldehyde (HCHO) at room temperature is an important method for HCHO removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. However, the stability of this catalyst remains unexplored. In this study, Pt-TiO{sub 2} (Pt-P25) catalysts with and without adsorbed halogen ions (including F{sup −}, Cl{sup −}, Br{sup −}, and I{sup −}) were prepared through impregnation and ion modification. Pt-TiO{sub 2} samples with adsorbed halogen ions exhibited reduced catalytic activity for formaldehyde decomposition at room temperature compared with the Pt-TiO{sub 2} sample; the catalytic activity followed the order of F-Pt-P25, Cl-Pt-P25, Br-Pt-P25, and I-Pt-P25. Characterization results (including XRD, TEM, HRTEM, BET, XPS, and metal dispersion) showed that the adsorbed halogen ions can poison Pt nanoparticles (NPs), thereby reducing the HCHO oxidation activity of Pt-TiO{sub 2}. The poison mechanism is due to the strong adsorption of halogen ions on the surface of Pt NPs. The adsorbed ions form coordination bonds with surface Pt atoms by transferring surplus electrons into the unoccupied 5d orbit of the Pt atom, thereby inhibiting oxygen adsorption and activation of the Pt NP surface. Moreover, deactivation rate increases with increasing diameter of halogen ions. This study provides new insights into the fabrication of high-performance Pt-based catalysts for indoor air purification.

  4. On exhaust emissions from petrol-fuelled passenger cars at low ambient temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Laurikko, J. [VTT Energy, Espoo (Finland). Energy Use

    1998-11-01

    The study at hand deals with regulated and unregulated exhaust emissions from petrol-fuelled cars at low ambient temperatures with present-day or near-future exhaust after treatment systems. The subject has been investigated at VTT over a decade and this report compiles data from various sub-studies carried out between the years 1993 - 1997. Each one of them viewed different aspects of the phenomenon, like determining the low-temperature response of today`s new cars employing three-way catalytic converters or assessing the long-term durability and the influence of vehicle mileage upon the low-temperature emissions performance. Within these studies, together more than 120 cars of model years from 1990 to 1997 have been tested. Most of them were normal, in-service vehicles with total mileages differing between only a few thousand kilometres for new cars up to 80,000 km or even more for the in-use vehicles. Both the US FTP75 and the European test cycle have been employed, and the ambient temperatures ranged from the baseline (+22 deg C) down to +- O deg C, -7 deg C and in some cases even to -20 deg C. The studies attested that new cars having today`s advanced emissions control systems produced fairly low levels of emissions when tested in conditions designated in the regulations that are the basis of the current new-vehicle certification. However, this performance was not necessarily attained at ambient temperatures that were below the normative range. Fairly widespread response was recorded, and cars having almost equal emissions output at baseline could produce largely deviating outcomes in low-temperature conditions. On average, CO and HC emissions increased by a factor of five to 10, depending on the ambient temperature and vehicle type. However, emissions of NO{sub x} were largely unaffected. Apart from these regulated emissions, many unregulated species were also determined, either by using traditional sampling and chromatography methods or on-line, employing

  5. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl

    2015-01-01

    For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling of the ac...... for standard SCR. Finally, the role of a nitrate/nitrite equilibrium and the possible in uence of Cu dimers and Brønsted sites are discussed, and an explanation is offered as to how a catalyst can be effective for SCR, while being a poor catalyst for NO oxidation to NO2....... spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The calculated activation energy by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate determining...

  6. Mean field approximation for the kinetics of the selective catalytic reduction of NO by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Santos, M.; Bodanese, J.P. [Centro de Ensino Sao Jose, Universidade do Vale do Itajai (Brazil); S. Grandi, B.C. da [Departamento de Fisica, Universidade Federal de Santa Catarina, Florianopolis (Brazil)

    2007-04-15

    In this work we study a catalytic reaction model among three monomers in order to understand the chemical kinetics of the selective catalytic reduction of nitrogen oxide by ammonia (4NO+4NH{sub 3}+O{sub 2}{yields}4N{sub 2}+6H{sub 2}O). Our model takes into account the formation of the intermediate species in the global scheme of the reaction. In order to determine the dynamical behaviour of the model we used single site approximation method. In this approach we have observed that, depending on the values of the control parameters, the model presents an active or an inactive phase. In fact, the dynamical phase diagram of the model exhibits a first order line separating these two phases. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Role of Calcination Temperature on the Hydrotalcite Derived MgO–Al2O3 in Converting Ethanol to Butanol

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Santosa, Daniel M.; Li, Xiaohong S.; Devaraj, Arun; Karkamkar, Abhijeet J.; Wang, Yong

    2015-10-09

    In the base catalyzed ethanol condensation reactions, the calcined MgO-Al2O3 derived hydrotalcites used broadly as catalytic material and the calcination temperature plays a big role in determining the catalytic activity. The characteristic of the hydrotalcite material treated between catalytically relevant temperatures 450ºC and 800ºC have been studied with respect to the physical, chemical, and structural properties and compared with catalytic activity testing. With the increasing calcination temperature, the total measured catalytic basicity dropped linearly with the calcination temperature and the total measured acidity stayed the same for all the calcination temperatures except 800ºC. However, the catalyst activity testing does not show any direct correlation between the measured catalytic basicity and the catalyst activity to the ethanol condensation reaction to form 1-butanol. The highest ethanol conversion of 44 percent with 1-butanol selectivity of 50 percent was achieved for the 600ºC calcined hydrotalcite material.

  8. Selective catalytic reduction system and process for control of NO.sub.x emissions in a sulfur-containing gas stream

    Science.gov (United States)

    Sobolevskiy, Anatoly

    2015-08-11

    An exhaust gas treatment process, apparatus, and system for reducing the concentration of NOx, CO and hydrocarbons in a gas stream, such as an exhaust stream (29), via selective catalytic reduction with ammonia is provided. The process, apparatus and system include a catalytic bed (32) having a reducing only catalyst portion (34) and a downstream reducing-plus-oxidizing portion (36). Each portion (34, 36) includes an amount of tungsten. The reducing-plus-oxidizing catalyst portion (36) advantageously includes a greater amount of tungsten than the reducing catalyst portion (36) to markedly limit ammonia salt formation.

  9. A cold-adapted endoglucanase from camel rumen with high catalytic activity at moderate and low temperatures: an anomaly of truly cold-adapted evolution in a mesophilic environment.

    Science.gov (United States)

    Khalili Ghadikolaei, Kamran; Gharechahi, Javad; Haghbeen, Kamahldin; Akbari Noghabi, Kambiz; Hosseini Salekdeh, Ghasem; Shahbani Zahiri, Hossein

    2018-03-01

    Endoglucanases are important enzymes in plant biomass degradation. They have current and potential applications in various industrial sectors including human and animal food processing, textile, paper, and renewable biofuel production. It is assumed that the cold-active endoglucanases, with high catalytic rates in moderate and cold temperatures, can improve the cost-effectiveness of industrial processes by lowering the need for heating and, thus, energy consumption. In this study, the endoglucanase CelCM3 was procured from a camel rumen metagenome via gene cloning and expression in Escherichia coli BL21 (DE3). The maximum activity of the enzyme on carboxymethyl cellulose (CMC) was obtained at pH 5 and 30 °C with a V max and K m of 339 U/mg and 2.57 mg/ml, respectively. The enzyme with an estimated low melting temperature of 45 °C and about 50% activity at 4 °C was identified to be cold-adapted. A thermodynamic analysis corroborated that CelCM3 with an activation energy (E a ), enthalpy of activation (ΔH), and Gibb's free energy (ΔG) of, respectively, 18.47 kJ mol -1 , 16.12 kJ mol -1 , and 56.09 kJ mol -1 is a cold-active endoglucanase. In addition, CelCM3 was tolerant of metal ions, non-ionic detergents, urea, and organic solvents. Given these interesting characteristics, CelCM3 shows promise to meet the requirements of industrial applications.

  10. Formation of nanocrystals embedded in a silicon nitride film at a low temperature ({<=}200 deg. C)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung-Min; Kim, Tae-Hwan [Department of Nano Science and Technology, University of Seoul, Seoul 130-743 (Korea, Republic of); Hong, Wan-Shick [Department of Nano Science and Technology, University of Seoul, Seoul 130-743 (Korea, Republic of)], E-mail: wshong@uos.ac.kr

    2008-12-15

    Silicon-rich silicon nitride films with embedded silicon nanocrystals (Si NCs) were fabricated successfully on plastic substrates at a low temperature by catalytic chemical vapor deposition. A mixture of SiH{sub 4}, NH{sub 3} and H{sub 2} was used as a source gas. Formation of the silicon nanocrystals was analyzed by photoluminescence spectra and was confirmed by transmission electron microscopy. The formation of Si NCs required an H{sub 2}/SiH{sub 4} mixture ratio that was higher than four.

  11. Catalytic Hydrogenation of CO2 to Methanol: Study of Synergistic Effect on Adsorption Properties of CO2 and H2 in CuO/ZnO/ZrO2 System

    Directory of Open Access Journals (Sweden)

    Chunjie Huang

    2015-11-01

    Full Text Available A series of CuO/ZnO/ZrO2 (CZZ catalysts with different CuO/ZnO weight ratios have been synthesized by citrate method and tested in the catalytic hydrogenation of CO2 to methanol. Experimental results showed that the catalyst with the lowest CuO/ZnO weight ratio of 2/7 exhibited the best catalytic performance with a CO2 conversion of 32.9%, 45.8% methanol selectivity, and a process delivery of 193.9 gMeOH·kgcat−1·h−1. A synergetic effect is found by systematic temperature-programmed-desorption (TPD studies. Comparing with single and di-component systems, the interaction via different components in a CZZ system provides additional active sites to adsorb more H2 and CO2 in the low temperature range, resulting in higher weight time yield (WTY of methanol.

  12. Heterogeneous catalytic materials solid state chemistry, surface chemistry and catalytic behaviour

    CERN Document Server

    Busca, Guido

    2014-01-01

    Heterogeneous Catalytic Materials discusses experimental methods and the latest developments in three areas of research: heterogeneous catalysis; surface chemistry; and the chemistry of catalysts. Catalytic materials are those solids that allow the chemical reaction to occur efficiently and cost-effectively. This book provides you with all necessary information to synthesize, characterize, and relate the properties of a catalyst to its behavior, enabling you to select the appropriate catalyst for the process and reactor system. Oxides (used both as catalysts and as supports for cata

  13. Twinning in fcc lattice creates low-coordinated catalytically active sites in porous gold

    Energy Technology Data Exchange (ETDEWEB)

    Krajčí, Marian [Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84511 Bratislava (Slovakia); Kameoka, Satoshi; Tsai, An-Pang [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2016-08-28

    We describe a new mechanism for creation of catalytically active sites in porous gold. Samples of porous gold prepared by de-alloying Al{sub 2}Au exhibit a clear correlation between the catalytic reactivity towards CO oxidation and structural defects in the fcc lattice of Au. We have found that on the stepped (211) surfaces quite common twin boundary defects in the bulk structure of porous gold can form long close-packed rows of atoms with the coordination number CN = 6. DFT calculations confirm that on these low-coordinated Au sites dioxygen chemisorbs and CO oxidation can proceed via the Langmuir–Hinshelwood mechanism with the activation energy of 37 kJ/mol or via the CO–OO intermediate with the energy barrier of 19 kJ/mol. The existence of the twins in porous gold is stabilized by the surface energy.

  14. Catalytic process for tritium exchange reaction

    International Nuclear Information System (INIS)

    Hansoo Lee; Kang, H.S.; Paek, S.W.; Hongsuk Chung; Yang Geun Chung; Sook Kyung Lee

    2001-01-01

    The catalytic activities for a hydrogen isotope exchange were measured through the reaction of a vapor and gas mixture. The catalytic activity showed to be comparable with the published data. Since the gas velocity is relatively low, the deactivation was not found clearly during the 5-hour experiment. Hydrogen isotope transfer experiments were also conducted through the liquid phase catalytic exchange reaction column that consisted of a catalytic bed and a hydrophilic bed. The efficiencies of both the catalytic and hydrophilic beds were higher than 0.9, implying that the column performance was excellent. (author)

  15. Room-temperature synthesis and enhanced catalytic performance of silver-reduced graphene oxide nanohybrids

    International Nuclear Information System (INIS)

    Thu, Tran Viet; Ko, Pil Ju; Phuc, Nguyen Huu Huy; Sandhu, Adarsh

    2013-01-01

    The synthesis of supported, ultrasmall metallic nanoparticles (NPs) is of great importance for catalytic applications. In this study, silver-reduced graphene oxide nanohybrids (Ag–rGO NHs) were prepared by reducing Ag ions and graphene oxide (GO) at room temperature using sodium borohydride (NaBH 4 ) and trisodium citrate. The resulting products were characterized using UV–Vis spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy. The rich chemistry of GO surface provided many sites for the nucleation of Ag ions and efficiently limited their growth. Ag NPs were uniformly grown on basal planes of rGO with a high density (∼1,700 NPs μm −2 ) and well-defined size (3.6 ± 0.6 nm) as evidenced in SEM and HRTEM studies. The resulting Ag–rGO NHs were readily dispersed in water and exhibited enhanced catalytic activity toward the reduction of 4-nitrophenol by NaBH 4 in comparison to unsupported Ag NPs. The role of rGO as an excellent support for Ag catalyst is discussed

  16. Room-temperature synthesis and enhanced catalytic performance of silver-reduced graphene oxide nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Thu, Tran Viet, E-mail: thu@eiiris.tut.ac.jp; Ko, Pil Ju, E-mail: ko@eiiris.tut.ac.jp [Toyohashi University of Technology, Electronics-Inspired Interdisciplinary Research Institute (Japan); Phuc, Nguyen Huu Huy [Toyohashi University of Technology, Department of Electrical and Electronic Information Engineering (Japan); Sandhu, Adarsh [Toyohashi University of Technology, Electronics-Inspired Interdisciplinary Research Institute (Japan)

    2013-10-15

    The synthesis of supported, ultrasmall metallic nanoparticles (NPs) is of great importance for catalytic applications. In this study, silver-reduced graphene oxide nanohybrids (Ag-rGO NHs) were prepared by reducing Ag ions and graphene oxide (GO) at room temperature using sodium borohydride (NaBH{sub 4}) and trisodium citrate. The resulting products were characterized using UV-Vis spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy. The rich chemistry of GO surface provided many sites for the nucleation of Ag ions and efficiently limited their growth. Ag NPs were uniformly grown on basal planes of rGO with a high density ({approx}1,700 NPs {mu}m{sup -2}) and well-defined size (3.6 {+-} 0.6 nm) as evidenced in SEM and HRTEM studies. The resulting Ag-rGO NHs were readily dispersed in water and exhibited enhanced catalytic activity toward the reduction of 4-nitrophenol by NaBH{sub 4} in comparison to unsupported Ag NPs. The role of rGO as an excellent support for Ag catalyst is discussed.

  17. Low to moderate temperature nanolaminate heater

    Science.gov (United States)

    Eckels, J Del [Livermore, CA; Nunes, Peter J [Danville, CA; Simpson, Randall L [Livermore, CA; Hau-Riege, Stefan [Fremont, CA; Walton, Chris [Oakland, CA; Carter, J Chance [Livermore, CA; Reynolds, John G [San Ramon, CA

    2011-01-11

    A low to moderate temperature heat source comprising a high temperature energy source modified to output low to moderate temperatures wherein the high temperature energy source modified to output low to moderate temperatures is positioned between two thin pieces to form a close contact sheath. In one embodiment the high temperature energy source modified to output low to moderate temperatures is a nanolaminate multilayer foil of reactive materials that produces a heating level of less than 200.degree. C.

  18. Synergetic mechanism of methanol–steam reforming reaction in a catalytic reactor with electric discharges

    International Nuclear Information System (INIS)

    Kim, Taegyu; Jo, Sungkwon; Song, Young-Hoon; Lee, Dae Hoon

    2014-01-01

    Highlights: • Methanol–steam reforming was performed on Cu catalysts under an electric discharge. • Discharge had a synergetic effect on the catalytic reaction for methanol conversion. • Discharge lowered the temperature for catalyst activation or light off. • Discharge controlled the yield and selectivity of species in a reforming process. • Adsorption triggered by a discharge was a possible mechanism for a synergetic effect. - Abstract: Methanol–steam reforming was performed on Cu/ZnO/Al 2 O 3 catalysts under an electric discharge. The discharge occurred between the electrodes where the catalysts were packed. The electric discharge was characterized by the discharge voltage and electric power to generate the discharge. The existence of a discharge had a synergetic effect on the catalytic reaction for methanol conversion. The electric discharge provided modified reaction paths resulting in a lower temperature for catalyst activation or light off. The discharge partially controlled the yield and selectivity of species in a reforming process. The aspect of control was examined in view of the reaction kinetics. The possible mechanisms for the synergetic effect between the catalytic reaction and electric discharge on methanol–steam reforming were addressed. A discrete reaction path, particularly adsorption triggered by an electric discharge, was suggested to be the most likely mechanism for the synergetic effect. These results are expected to provide a guide for understanding the plasma–catalyst hybrid reaction

  19. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion.

    Science.gov (United States)

    Pozan, Gulin Selda

    2012-06-30

    The aim of this work was to study combustion of toluene (1000ppm) over MnO(2) modified with different supports. α-Al(2)O(3) and γ-Al(2)O(3) obtained from Boehmite, γ-Al(2)O(3) (commercial), SiO(2), TiO(2) and ZrO(2) were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO(2) was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO(2)/α-Al(2)O(3)(B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289°C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. The Catalytic Activity of Modified Zeolite Lanthanum on the Catalytic Cracking of Al-Duara Atmospheric Distillation Residue

    Directory of Open Access Journals (Sweden)

    Karim Khalifa Esgair

    2016-03-01

    Full Text Available Atmospheric residue fluid catalytic cracking was selected as a probe reaction to test the catalytic performance of modified NaY zeolites and prepared NaY zeolites. Modified NaY zeolites have been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with lanthanum and the weight percent added are 0.28, 0.53, and 1.02 respectively. The effects of addition of lanthanum to zeolite Y in different weight percent on the cracking catalysts were investigated using an experimental laboratory plant scale of fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV range of 6 to 24 h-1, and the range of temperature from 450 to 510 oC. The activity of the catalyst with 1.02 wt% lanthanum has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the lanthanum causes an increase in the thermal stability of the zeolite.

  1. Thermal buffering performance of composite phase change materials applied in low-temperature protective garments

    Science.gov (United States)

    Yang, Kai; Jiao, Mingli; Yu, Yuanyuan; Zhu, Xueying; Liu, Rangtong; Cao, Jian

    2017-07-01

    Phase change material (PCM) is increasingly being applied in the manufacturing of functional thermo-regulated textiles and garments. This paper investigated the thermal buffering performance of different composite PCMs which are suitable for the application in functional low-temperature protective garments. First, according to the criteria selecting PCM for functional textiles/garments, three kinds of pure PCM were selected as samples, which were n-hexadecane, n-octadecane and n-eicosane. To get the adjustable phase change temperature range and higher phase change enthalpy, three kinds of composite PCM were prepared using the above pure PCM. To evaluate the thermal buffering performance of different composite PCM samples, the simulated low-temperature experiments were performed in the climate chamber, and the skin temperature variation curves in three different low temperature conditions were obtained. Finally composite PCM samples’ thermal buffering time, thermal buffering capacity and thermal buffering efficiency were calculated. Results show that the comprehensive thermal buffering performance of n-octadecane and n-eicosane composite PCM is the best.

  2. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    real catalyst. The ISPS-packed-bed catalysed conversion of rapeseed oil revealed low activity but advantageous flow properties. A number of functionalised, organic bases have been tested for their activity in transesterification of trioctanoate with methanol, especially guanidines. The activity for trioctanoate conversion was promising, however, hygroscopic catalysts be may lead to saponification of the triglyceride. Hydrodeoxygenation is treated in chapter 3. The reaction routes and activity in batch hydrodeoxygenation are strongly dependent on the supported noble metal catalyst and temperature used for the conversion to alkanes. Generally, Pt and Pd were the most active metals and have highest selectivity for decarboxylation reaction. Stearic or oleic acid were converted much faster than tripalmitin. The deoxygenation was performed in a continuous trickle-bed reactor over 2 wt% Pd/Sibunit at 300 deg. C. 10 wt% stearic acid yielded almost complete and selective conversion to heptadecane in 5% H{sub 2}/Ar at 20 bar, however pure Ar gas led to deactivation. A deactivation profile by coking builds up as a function of the distance from the reactor inlet. A constant conversion of 12% was obtained with neat stearic acid in 7 days time-on-stream of the spent catalyst. The activity for deoxygenation in continuous mode decreased as stearic acid > ethyl stearate > tristearin under 5 % H{sub 2} in Ar, while lack of H{sub 2} in the feed quickly led to complete deactivation of the catalysts in all feeds. The work is concluded with a summary and an outlook in chapter 4. (Author)

  3. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  4. Improving catalytic selectivity through control of adsorption orientation

    Science.gov (United States)

    Pang, Simon H.

    In this thesis, we present an investigation, starting from surface science experiments, leading to design of supported catalysts, of how adsorption orientation can be used to affect reaction selectivity of highly functional molecules. The surface chemistry of furfuryl alcohol and benzyl alcohol and their respective aldehydes was studied on a Pd(111) single-crystal surface under ultra-high vacuum conditions. Temperature-programmed desorption experiments showed that synergistic chemistry existed between the aromatic ring and the oxygen-containing functional group, each allowing the other to participate in reaction pathways that a monofunctional molecule could not. Most important of these was a deoxygenation reaction that occurred more readily when the surface was crowded by the highest exposures. High-resolution electron energy loss spectroscopy revealed that at these high exposures, molecules were oriented upright on the surface, with the aromatic function extending into vacuum. In contrast, at low exposures, molecules were oriented flat on the surface. The upright adsorption geometry was correlated with deoxygenation, whereas the flat-lying geometry was correlated with decarbonylation. The insight gained from surface science experiments was utilized in catalyst design. Self-assembled monolayers of alkanethiolates were used to systematically reduce the average surface ensemble size, and the reaction selectivity was tracked. When a sparsely-packed monolayer was used, such as one formed by 1-adamantanethiol, the reactant furfural was still able to lie flat on the surface and the reaction selectivity was similar to that of the uncoated catalyst. However, when a densely-packed monolayer, formed by 1-octadecanethiol, was used, furfural was not able to adsorb flat on the surface and instead adopted an upright conformation, leading to a drastic increase in aldehyde hydrogenation and hydrodeoxygenation reaction selectivity. Using an even higher sulfur coverage from a

  5. Catalytic gasification in fluidized bed, of orange waste. Comparison with non catalytic gasification

    International Nuclear Information System (INIS)

    Aguiar Trujillo, Leonardo; Marquez Montesinos, Francisco; Ramos Robaina, Boris A.; Guerra Reyes, Yanet; Arauzo Perez, Jesus; Gonzalo Callejo, Alberto; Sanchez Cebrian, Jose L

    2011-01-01

    The industry processing of the orange, generates high volumes of solid waste. This waste has been used as complement in the animal feeding, in biochemical processes; but their energy use has not been valued by means of the gasification process. They were carried out gasification studies with air in catalytic fluidized bed (using dolomite and olivine as catalysts in a secondary reactor, also varying the temperature of the secondary reactor and the catalyst mass), of the solid waste of orange and the results are compared with those obtained in the gasification with non catalytic air. In the processes we use a design of complete factorial experiment of 2k, valuing the influence of the independent variables and their interactions in the answers, using the software Design-Expert version 7 and a grade of significance of 95 %. The results demonstrate the qualities of the solid waste of orange in the energy use by means of the gasification process for the treatment of these residuals, obtaining a gas of low caloric value. The use of catalysts also diminishes the yield of tars obtained in the gasification process, being more active the dolomite that the olivine in this process. (author)

  6. Evolution of low-temperature phases in a low-temperature structural transition of a La cuprate

    International Nuclear Information System (INIS)

    Inoue, Y.; Horibe, Y.; Koyama, Y.

    1997-01-01

    The microstructure produced by a low-temperature structural phase transition in La 1.5 Nd 0.4 Sr 0.1 CuO 4 has been examined by transmission electron microscopy with the help of imaging plates. The low-temperature transition was found to be proceeded not only by the growth of the Pccn/low-temperature-tetragonal phases nucleated along the twin boundary but also by the nucleation and growth of the phases in the interior of the low-temperature-orthorhombic domain. In addition, because the map of the octahedron tilt as an order parameter is not identical to that of the spontaneous strain accompanied by the transition, the microstructure below the transition is understood to be a very complex mixture of the low-temperature phases. copyright 1997 The American Physical Society

  7. Adsorbent catalytic nanoparticles and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  8. Urea-SCR Temperature Investigation for NOx Control of Diesel Engine

    Directory of Open Access Journals (Sweden)

    Asif Muhammad

    2015-01-01

    Full Text Available SCR (selective catalytic reduction system is continuously being analyzed by many researchers worldwide on various concerns due to the stringent nitrogen oxides (NOx emissions legislation for heavy-duty diesel engines. Urea-SCR includes AdBlue as urea source, which subsequently decomposes to NH3 (ammonia being the reducing agent. Reaction temperature is a key factor for the performance of urea-SCR system, as urea decomposition rate is sensitive to a specific temperature range. This particular study was directed to investigate the temperature of the SCR system in diesel engine with the objective to confirm that whether the appropriate temperature is attained for occurrence of urea based catalytic reduction or otherwise and how the system performs on the prescribed temperature range. Diesel engine fitted with urea-SCR exhaust system has been operated on European standard cycle for emission testing to monitor the temperature and corresponding nitrogen oxides (NOx values on specified points. Moreover, mathematical expressions for approximation of reaction temperature are also proposed which are derived by applying energy conservation principal and gas laws. Results of the investigation have shown that during the whole testing cycle system temperature has remained in the range where urea-SCR can take place with best optimum rate and the system performance on account of NOx reduction was exemplary as excellent NOx conversion rate is achieved. It has also been confirmed that selective catalytic reduction (SCR is the best suitable technology for automotive engine-out NOx control.

  9. Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

    International Nuclear Information System (INIS)

    Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F.C.; Geske, M.; Taha, A.; Pelzer, K.; Schloegl, R.

    2006-01-01

    A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000 deg. C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100 μm sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10 ms. A detection time resolution of up to 20 ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N 2 and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N 2 to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250 deg. C on a Pt catalyst are presented. The detection of CH 3 · radicals is successfully demonstrated

  10. Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

    Science.gov (United States)

    Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F. C.; Geske, M.; Taha, A.; Pelzer, K.; Schlögl, R.

    2006-05-01

    A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000°C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100μm sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10ms. A detection time resolution of up to 20ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N2 and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N2 to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250°C on a Pt catalyst are presented. The detection of CH3• radicals is successfully demonstrated.

  11. H2CAP - Hydrogen assisted catalytic biomass pyrolysis for green fuels

    DEFF Research Database (Denmark)

    Arndal, Trine Marie Hartmann; Høj, Martin; Jensen, Peter Arendt

    2014-01-01

    Pyrolysis of biomass produces a high yield of condensable oil at moderate temperature and low pressure.This bio-oil has adverse properties such as high oxygen and water contents, high acidity and immiscibility with fossil hydrocarbons. Catalytic hydrodeoxygenation (HDO) is a promising technology...... that can be used to upgrade the crude bio-oil to fuel-grade oil. The development of the HDO process is challenged by rapid catalyst deactivation, instability of the pyrolysis oil, poorly investigated reaction conditions and a high complexity and variability of the input oil composition. However, continuous...... catalytic hydropyrolysis coupled with downstream HDO of the pyrolysis vapors before condensation shows promise (Figure 1). A bench scale experimental setup will be constructed for the continuous conversion of solid biomass (100g /h) to low oxygen, fuel-grade bio-oil. The aim is to provide a proof...

  12. Study of the influence of the amount of PBI-H{sub 3}PO{sub 4} in the catalytic layer of a high temperature PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, Justo; Canizares, Pablo; Rodrigo, Manuel A.; Linares, Jose J.; Pinar, F. Javier [Chemical Engineering Department, Enrique Costa Building, University of Castilla-La Mancha, Av. Camilo Jose Cela, n 12, 13071, Ciudad Real (Spain)

    2010-02-15

    The influence of the amount of polybenzimidazole (PBI)-H{sub 3}PO{sub 4} (normalized with respect to the PBI loading, which expressed as C/PBI weight ratio) content in both the anode and cathode has been studied for a PBI-based high temperature proton exchange membrane (PEM) fuel cell. The electrodes prepared with different amounts of PBI have been characterized physically, by measuring the pore size distribution, and visualizing the surface microstructure. Afterwards, the electrochemical behaviour of the electrodes has been evaluated. The catalytic electrochemical activity has been measured by voltamperometry for each electrode prepared with a different PBI content, and the cell performance results have been studied, supported by the impedance spectra, in order to determine the influence of the PBI loading in each electrode. The best results have been achieved with a C/PBI weight ratio of 20, for both the anode and the cathode. A lower C/PBI weight ratio (larger amount of PBI in the catalytic layer) reduced the electrocatalytic activity, and impaired the mass transport processes, due to the large amount of polymer covering the catalyst particle, lowering the cell performance. A higher C/PBI weight ratio (lower amount of PBI in the catalytic layer) reduced the electrocatalytic activity, and slightly increased the ohmic resistance. The low amount of the polymeric ionic carrier PBI-H{sub 3}PO{sub 4} limited the proton mobility, despite of the presence of large amounts of ''free'' H{sub 3}PO{sub 4} in the catalytic layer. (author)

  13. High Temperature Catalytic Combustion Suppports Final Report CRADA No. TSB-0841-94

    Energy Technology Data Exchange (ETDEWEB)

    Hair, Lucy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magno, Scott [Catalytic Combustion Systems, Inc., Mountain View, CA (United States)

    2018-01-19

    This Small Business CRADA between LLNL and Catalytica was executed on January 25, 1995. The total estimated cost of this project was 113K. LLNL's contribution was estimated at $50K funded under the DOE/Defense Program Small Business Initiative. Catalytica's in-kind contribution was estimated at 63K. Catalytic combusion catalyst systems operate at temperatures from 600°C to above 1300°C. Catalytica has developed technology that limits the catalyst temperature to below 1000°C. At temperatures in the range of 850 to 1000°C, the thermal stability of the catalyst is an important issue. Typical supports such as stabilized aluminas, hexaluminates, zirconia and stabilized zirconia supports are typically used but lack either thermal stability or other desirable properties. Catalytica had developed a new concept for thermally stable mixed oxide supports but this concept required the preparation of molecularly uniform precursors; that is, prior to high temperature treatment of these materials, the elements that make up the mixed oxide must be as nearly uniform as possible on a molecular level. The technique of sol gel processing appeared to be the preferred technique to make these molecularly uniform precursors, and a cooperative program with LLNL was established to prepare and test the proposed compounds. Catalytica proposed the composition and concentration levels for the materials to be prepared.

  14. Abatement of phenolic mixtures by catalytic wet oxidation enhanced by Fenton's pretreatment: Effect of H2O2 dosage and temperature

    International Nuclear Information System (INIS)

    Santos, A.; Yustos, P.; Rodriguez, S.; Simon, E.; Garcia-Ochoa, F.

    2007-01-01

    Catalytic wet oxidation (CWO) of a phenolic mixture containing phenol, o-cresol and p-cresol (500 mg/L on each pollutant) has been carried out using a commercial activated carbon (AC) as catalyst, placed in a continuous three-phase reactor. Total pressure was 16 bar and temperature was 127 deg. C. Pollutant conversion, mineralization, intermediate distribution, and toxicity were measured at the reactor outlet. Under these conditions no detoxification of the inlet effluent was found even at the highest catalyst weight (W) to liquid flow rate (Q L ) ratio used. On the other hand, some Fenton Runs (FR) have been carried out in a batch way using the same phenolic aqueous mixture previously cited. The concentration of Fe 2+ was set to 10 mg/L. The influence of the H 2 O 2 amount (between 10 and 100% of the stoichiometric dose) and temperature (30, 50, and 70 deg. C) on phenols conversion, mineralization, and detoxification have been analyzed. Phenols conversion was near unity at low hydrogen peroxide dosage but mineralization and detoxification achieved an asymptotic value at each temperature conditions. The integration of Fenton reagent as pretreatment of the CWO process remarkably improves the efficiency of the CWO reactor and allows to obtain detoxified effluents at mild temperature conditions and relatively low W/Q L values. For a given phenolic mixture a temperature range of 30-50 deg. C in the Fenton pretreatment with a H 2 O 2 dosage between 20 and 40% of the stoichiometric amount required can be proposed

  15. Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

    Science.gov (United States)

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

  16. Hydroconversion of coal tars: effect of the temperature of pyrolysis on the reactivity of tars

    Energy Technology Data Exchange (ETDEWEB)

    Lemberton, J.L.; Touzeyidio, M.; Guisnet, M.

    1988-12-01

    The hydroconversion of a low-temperature and of a high-temperature tar was carried out in the presence of a sulfided Ni and Mo on alumina catalyst - pure or mixed with an acid catalyst (HY zeolite). Significant amounts of light products can be obtained from low temperature tar, formed however through a non-catalytic process. On the contrary, there is a slight catalytic effect during the hydroprocessing of high temperature tar, but the yield in light products is very low. These results can be explained by an extensive poisoning of the NiMo on alumina catalyst by coke which is initiated by the O- and N-containing compounds of the tars. 10 refs., 1 fig., 3 tabs.

  17. The potential of medium-pore zeolites for improved propene yields from catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Bager, F.; Salas, N.; Ernst, S. [Technische Univ. Kaiserslautern (Germany). Dept. of Chemistry, Chemical Technology

    2011-07-01

    The medium-pore zeolites ZSM-5 (MFI), ZSM-22 (TON), ZSM-23 (MTT), and EU-1 (EUO) were synthesized under hydrothermal conditions and modified by ion exchange to obtain the Broensted-acid forms. The activity and selectivity of these catalysts in catalytic cracking of a model compound, viz. n-octane, was studied in a fixed-bed flow-type reactor. The catalytic results clearly reflect the differences in the pore architectures of the tested zeolites on n-octane conversion and on the product selectivities. Over the zeolites with one-dimensional pore systems and without large intracrystalline cavities, a remarkable increase of the contribution of the monomolecular cracking mechanism could be observed as compared to the standard catalyst zeolite ZSM-5. This is indicated by a high selectivity for unsaturated products and, hence, increasing yields of propene. Large cavities in the pore system, viz. in the case of zeolite EU-1, increase the conversion in particular at lower temperatures. However, the large cavities also favor the formation of large transition states required for the classical bimolecular cracking mechanism, resulting in decreased selectivities for unsaturated products, increased selectivities for aromatics formation and faster deactivation. (orig.)

  18. Catalytic effect of halide additives ball milled with magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Malka, I.E.; Bystrzycki, J. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Czujko, T. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); CanmetENERGY, Hydrogen Fuel Cells and Transportation Energy, Natural Resources (Canada)

    2010-02-15

    The influence of various halide additives milled with magnesium hydride (MgH{sub 2}) on its decomposition temperature was studied. The optimum amount of halide additive and milling conditions were evaluated. The MgH{sub 2} decomposition temperature and energy of activation reduction were measured by temperature programmed desorption (TPD) and differential scanning calorimetry (DSC). The difference in catalytic efficiency between chlorides and fluorides of the various metals studied is presented. The effects of oxidation state, valence and position in the periodic table for selected halides on MgH{sub 2} decomposition temperature were also studied. The best catalysts, from the halides studied, for magnesium hydride decomposition were ZrF{sub 4}, TaF{sub 5}, NbF{sub 5}, VCl{sub 3} and TiCl{sub 3}. (author)

  19. The Influence of oxide additives on Ni/Al2O3 catalysts in low temperature methane steam reforming

    International Nuclear Information System (INIS)

    Lazar, Mihaela; Dan, Monica; Mihet, Maria; Almasan, Valer

    2009-01-01

    Hydrogen is industrially produced by methane steam reforming. The process is catalytic and the usual catalyst is based on Ni as the active element. The main problem of this process is its inefficiency. It requires high temperatures at which Ni also favors the formation of graphite, which deactivates the catalysts. Ni has the advantage of being much cheaper than noble metal catalysts, so many researches are done in order to improve the properties of supported Ni catalysts and to decrease the temperature at which the process is energetically efficient. In order to obtain catalysts with high activity and stability, it is essential to maintain the dispersion of the active phase (Ni particles) and the stability of the support. Both properties can be improved by addition of a second oxide to the support. In this paper we present the results obtained in preparation and characterization of Ni/Al 2 O 3 catalysts modified by addition of CeO 2 and La 2 O 3 to alumina support. The following catalysts were prepared by impregnation method: Ni/Al 2 O 3 , Ni/CeO 2 -Al 2 O 3 and Ni/La 2 O 3 -Al 2 O 3 (10 wt.% Ni and 6 wt.% additional oxide). The catalytic surface was characterized by N 2 adsorption - desorption isotherms. The hydrogen - surface bond was characterized by Thermo-Programmed-Desorption (TPD) method. All catalysts were tested in steam reforming reaction of methane in the range of 600 - 700 deg. C, at atmospheric pressure working with CH 4 :H 2 O ratio of 1:3. The modified catalysts showed a better catalytic activity and selectivity for H 2 and CO 2 formation, at lower temperatures than the simple Ni/Al 2 O 3 catalyst. (authors)

  20. The effect of low temperature cryocoolers on the development of low temperature superconducting magnets

    International Nuclear Information System (INIS)

    Green, Michael A.

    2000-01-01

    The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report will also show when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given

  1. Mesoporous Fe-containing ZSM-5 zeolite single crystal catalysts for selective catalytic reduction of nitric oxide by ammonia

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Egeblad, Kresten; Kustova, Marina

    2007-01-01

    Mesoporous and conventional Fe-containing ZSM-5 catalysts (0.5–8 wt% Fe) were prepared using a simple impregnationmethod and tested in NO selective catalytic reduction (SCR) with NH3. It was found that mesoporous Fe-ZSM-5 catalysts exhibit higher SCR activities than comparable conventional cataly...

  2. Low temperature distillation

    Energy Technology Data Exchange (ETDEWEB)

    Vandegrift, J N; Postel, C

    1929-04-09

    To recover gas, oil tars, and coked residues by low temperature distillation from bituminous coals, lignites, oil shales, and the like, the raw material is fed from a hopper into a rotary retort which is zonally heated, the temperature being greatest at the discharge end. The material is heated first to a relatively low temperature, thereby removing the moisture and lighter volatiles which are withdrawn through a pipe by the suction of a pump, while the higher boiling point volatiles and fixed gases are withdrawn by suction through an outlet from the higher temperature zone. The vapors withdrawn from the opposite ends of the retort pass through separate vapor lines and condensers, and the suction in each end of the retort, caused by the pumps, is controlled by valves, which also control the location of the neutral point in the retort formed by said suction. Air and inert gas may be introduced into the retort from pipe and stack respectively through a pipe, and steam may be admitted into the high temperature zone through a pipe.

  3. Low temperature carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, A A

    1934-01-10

    A process is described in which coal is passed through a distillation chamber in one retort at a comparatively low temperature, then passing the coal through a distillation chamber of a second retort subjected to a higher temperature, thence passing the coal through the distillation chamber of a third retort at a still higher temperature and separately collecting the liquid and vapors produced from each retort.

  4. Low temperature synthesis of Zn nanowires by physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Philipp; Kast, Michael; Brueckl, Hubert [Austrian Research Centers GmbH ARC, Nano- Systemtechnologies, Donau-City-Strasse 1, A-1220 Wien (Austria)

    2007-07-01

    We demonstrate catalytic growth of zinc nanowires by physical vapor deposition at modest temperatures of 125-175 C on various substrates. In contrast to conventional approaches using tube furnaces our home-built growth system allows to control the vapor sources and the substrate temperature separately. The silicon substrates were sputter coated with a thin gold layer as metal catalyst. The samples were heated to the growth temperature and subsequently exposed to the zinc vapor at high vacuum conditions. The work pressure was adjusted by the partial pressure of oxygen or argon flow gas. Scanning electron microscopy and atomic force microscopy characterizations revealed that the nanowires exhibit straight, uniform morphology and have diameters in the range of 50-350 nm and lengths up to 70 {mu}m. The Zn nanowires grow independently of the substrates crystal orientation via a catalytic vapor-solid growth mechanism. Since no nanowire formation was observed without gold coating, we expect that the onedimensional growth is initiated by a surface reactive Au seed. ZnO nanowires can be produced in the same preparation chamber by oxidation at 500 C in 1atm (80% Ar, 20% O{sub 2}) for 1 hour. ZnO is highly attractive for sensor applications.

  5. Local Environment and Nature of Cu Active Sites in Zeolite-Based Catalysts for the Selective Catalytic Reduction of NOx

    NARCIS (Netherlands)

    Deka, U.|info:eu-repo/dai/nl/325811202; Lezcano-Gonzalez, I.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Beale, A.M.|info:eu-repo/dai/nl/325802068

    2013-01-01

    Cu-exchanged zeolites have demonstrated widespread use as catalyst materials in the abatement of NOx, especially from mobile sources. Recent studies focusing on Cu-exchanged zeolites with the CHA structure have demonstrated them to be excellent catalysts in the ammonia-assisted selective catalytic

  6. Catalytic synthesis of aromatic diisocyanates by means of carbonylation of nitrocompounds with carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, B K; Manov-Yuvenskii, V I; Khoshdurdev, Kh O; Novikov, S S [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1977-02-11

    The development of an active and selective heterogeneous catalyst for synthesis of aromatic diisocyanates has been studied. The catalytic ability of the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/ deposited on ..gamma..-Al/sub 2/O/sub 3/ has been investigated in the reactions of carbonylation of aromatic dinitrocompounds with carbon oxide. The effect of the catalyst composition, method of catalyst production, reaction temperature and pressure on the catalytic ability have been studied. It has been established that the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/(2-6:1:1) deposited on ..gamma..-Al/sub 2/O/sub 3/ is highly active and selective in the reactions of carbonilation of aromatic dinitrocompounds at 210 deg and 300 atm. It has been used for synthesis of aromatic diisocyanates in yield 32-75%.

  7. Radiation tests at cryogenic temperature on selected organic materials for LHC

    International Nuclear Information System (INIS)

    Humer, K.; Weber, H.W.; Szeless, B.; Tavlet, M.

    1997-01-01

    Future multi-TeV particle accelerators like the CERN Large Hadron Collider (LHC) will use superconducting magnets in which organic materials will be exposed to high radiation levels at temperatures as low as 2 K. A representative selection of organic materials comprising insulating films, cable insulations, epoxy resins and composites were exposed to neutron and gamma radiation of a nuclear reactor. Depending on the type of materials, the integrated radiation doses varied between 180 kGy and 155 MGy. During irradiation, the samples were kept close to the boiling temperature of liquid nitrogen, i.e. at 80 K, and thereafter stored in liquid nitrogen and transferred at the same temperature into the testing device for measurement of tensile and flexural strength. Tests were carried out on the same materials at similar dose rates at room temperature, and the results are compared with the ones obtained at cryogenic temperature. They show that within the selected dose range, a number of organic materials are suitable for use in radiation fields of the LHC at cryogenic temperature

  8. Investigation of a Pt3Sn/C Electro-Catalyst in a Direct Ethanol Fuel Cell Operating at Low Temperatures for Portable Applications

    OpenAIRE

    Zignani, S. C.; Gonzalez, E. R.; Baglio, V.; Siracusano, S.; Arico, A. S.

    2012-01-01

    A 20% Pt3Sn/C catalyst was prepared by reduction with formic acid and used in a direct ethanol fuel cell at low temperatures. The electro-catalytic activity of this bimetallic catalyst was compared to that of a commercial 20% Pt/C catalyst. The PtSn catalyst showed better results in the investigated temperature range (30 degrees-70 degrees C). Generally, Sn promotes ethanol oxidation by adsorption of OH species at considerably lower potentials compared to Pt, allowing the occurrence of a bifu...

  9. In situ DRIFTs investigation of the reaction mechanism over MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} (M = Fe, Co, Ni, Cu) for the selective catalytic reduction of NO{sub x} with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Hang; Zha, Kaiwen; Li, Hongrui; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

    2016-11-30

    Highlights: • MnO{sub x}-FeO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalyst has a strong NO oxidation ability. • A high dispersion of active components is achieved on catalyst surface. • At high temperatures, bidentate nitrate is the common active species. • The addition of Fe can improve the reactivity of gaseous NO{sub 2} and bridged nitrates. - Abstract: A series of MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} (M = Fe, Co, Ni, Cu) catalysts were synthesized by an impregnation method and used for selective catalytic reduction (SCR) of NO{sub x} with NH{sub 3}. The catalytic performances of various MnO{sub x}-MO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalysts were studied. It was found that MnO{sub x}-FeO{sub y}/Ce{sub 0.75}Zr{sub 0.25}O{sub 2} catalyst showed excellent low-temperature activity and a broad temperature window. The catalysts were characterized by N{sub 2} adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared transform spectroscopy (DRIFTS). Characterization of the catalyst confirmed the addition of iron oxide can enhance the NO oxidation ability of the catalyst which results in the outstanding low-temperature SCR activity. Meanwhile, iron oxides were well dispersed on catalyst surface which could avoid the agglomeration of active species, contributing to the strong interaction between active species and the support. More importantly, in situ DRIFTS results confirmed that bidentate nitrates are general active species on these catalysts, whereas the reactivity of gaseous NO{sub 2} and bridged nitrates got improved because of the addition of Fe.

  10. Determination of Henry’s law constant of light hydrocarbon gases at low temperatures

    International Nuclear Information System (INIS)

    Mohebbi, V.; Naderifar, A.; Behbahani, R.M.; Moshfeghian, M.

    2012-01-01

    Highlights: ► Henry’s constants of light hydrocarbon gases are reported at low temperatures. ► Solubility of iso-butane in water at low temperatures (275 K to 293 K) was measured. ► An expression of Krichevsky–Kasarnovsky equation is reported. - Abstract: The solubility of i-butane in water at the low temperatures was measured (274 K to 293 K). Additionally, Henry’s law constants of light hydrocarbons (methane, ethane, propane, i-butane, and n-butane) in water at the low temperatures are reported. A modified equation based on Krichevsky–Kasarnovsky equation is proposed to consider the effect of pressure and temperature on the equation parameters. Results show that Henry’s law constant of the selected components depends on temperature. It is deduced that pressure has a considerable effect on Henry’s law constant for methane, ethane, and propane, whereas this dependency for butanes is negligible.

  11. Denitration of medium level liquid radioactive wastes by catalytic destruction of nitrogen oxides

    International Nuclear Information System (INIS)

    Donato, A.; Ricci, G.

    1984-01-01

    The catalytic abatement by means of NH 3 of the NOsub(x) produced in the radwaste conditioning has been studied. With reference to the gas produced in a bituminization plant, the thermodynamics and the chemistry of the NOsub(x) catalytic reduction to nitrogen and H 2 O have been evaluated. The following operational parameters have been experimentally studied: the catalyst bed temperature; the gas residence time; the vapour concentration; the NOsub(x) concentration; the gas velocity; the catalyst grain size distribution; the catalyst time-life. Abatement yields of the order of 99,5% have been obtained following experimental conditions must be selected. In the case of a bituminization plant, a NOsub(x) catalytic reactor, if installed between the evaporator denitrator and the condenser, could reduce to less than 1/100 the volume of the NaNO 3 secondary wastes produced by the gas scrubbing

  12. Apparatus and Method for Low-Temperature Training of Shape Memory Alloys

    Science.gov (United States)

    Swanger, A. M.; Fesmire, J. E.; Trigwell, S.; Gibson, T. L.; Williams, M. K.; Benafan, O.

    2015-01-01

    An apparatus and method for the low-temperature thermo-mechanical training of shape memory alloys (SMA) has been developed. The experimental SMA materials are being evaluated as prototypes for applicability in novel thermal management systems for future cryogenic applications. Alloys providing two-way actuation at cryogenic temperatures are the chief target. The mechanical training regimen was focused on the controlled movement of rectangular strips, with S-bend configurations, at temperatures as low as 30 K. The custom holding fixture included temperature sensors and a low heat-leak linear actuator with a magnetic coupling. The fixture was mounted to a Gifford-McMahon cryocooler providing up to 25 W of cooling power at 20 K and housed within a custom vacuum chamber. Operations included both training cycles and verification of shape memory movement. The system design and operation are discussed. Results of the training for select prototype alloys are presented.

  13. A Temperature Window for the Synthesis of Single-Walled Carbon Nanotubes by Catalytic Chemical Vapor Deposition of CH4over Mo2-Fe10/MgO Catalyst

    Directory of Open Access Journals (Sweden)

    Yu Ouyang

    2009-01-01

    Full Text Available Abstract A temperature window for the synthesis of single-walled carbon nanotubes by catalytic chemical vapor deposition of CH4over Mo2-Fe10/MgO catalyst has been studied by Raman spectroscopy. The results showed that when the temperature is lower than 750 °C, there were few SWCNTs formed, and when the temperature is higher than 950 °C, mass amorphous carbons were formed in the SWCNTs bundles due to the self-decomposition of CH4. The temperature window of SWCNTs efficient growth is between 800 and 950 °C, and the optimum growth temperature is about 900 °C. These results were supported by transmission electron microscope images of samples formed under different temperatures. The temperature window is important for large-scale production of SWCNTs by catalytic chemical vapor deposition method.

  14. Correlation between Low Temperature Adaptation and Oxidative Stress in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Estéfani García-Rios

    2016-08-01

    Full Text Available Many factors, such as must composition, juice clarification, fermentation temperature or inoculated yeast strain, strongly affect the alcoholic fermentation and aromatic profile of wine. As fermentation temperature is effectively controlled by the wine industry, low-temperature fermentation (10-15 ºC is becoming more prevalent in order to produce white and rosé wines with more pronounced aromatic profiles. Elucidating the response to cold in Saccharomyces cerevisiae is of paramount importance for the selection or genetic improvement of wine strains. Previous research has shown the strong implication of oxidative stress response in adaptation to low temperature during the fermentation process. Here we aimed first to quantify the correlation between recovery after shock with different oxidants and cold, and then to detect the key genes involved in cold adaptation that belong to sulfur assimilation, peroxiredoxins, glutathione-glutaredoxins and thioredoxins pathways. To do so, we analyzed the growth of knockouts from the EUROSCARF collection S. cerevisiae BY4743 strain at low and optimal temperatures. The growth rate of these knockouts, compared with the control, enabled us to identify the genes involved, which were also deleted and validated as key genes in the background of two commercial wine strains with a divergent phenotype in their low-temperature growth. We identified three genes, AHP1, MUP1 and URM1, whose deletion strongly impaired low-temperature growth.

  15. Investigation on catalytic gasification of high-ash coal with mixing-gas in a small-scale fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Zhang, J.; Lin, J. [Fuzhou University, Fuzhou (China)

    2005-10-15

    The experimental study on the Yangquan high-ash coal catalytic gasification with mixing gas by using solid alkali or waste liquid of viscose fiber as the catalyst in a small-scale fluidized bed with 28 mm i.d. was carried out. The loading saturation levels of two catalysts in Yangquan high-ash coal are about 6%. Under the gasification temperature ranging from 830 to 900{sup o}C and from 900 to 920{sup o}C, the apparent reaction order of Yangquan high-ash coal with respect to the unreacted carbon fraction approximates to 2.3 and 1/3 for the non-catalyst case, respectively. Also, the different values of apparent reaction order in the two temperature ranges are presented for the case with 3% solid alkali catalyst loaded. At the low temperature ranging from 830 to 860{sup o}C, the apparent reaction order of catalytic gasification is 1 since enough active carbon sites on the coal surface are formed during the catalytic gasification by solid alkali. But at the high temperature ranging from 860 to 920{sup o}C, the sodium carbonate produced by the reaction of solid alkali with carbon dioxide can be easily fused, transferred and re-distributed, which affects the gasification reaction rate, and the apparent reaction order of catalytic gasification is reduced to 1.3. 10 refs., 9 figs., 4 tab s.

  16. One-pot low-temperature green synthesis of magnetic graphene nanocomposite for the selective reduction of nitrobenzene

    Science.gov (United States)

    Haridas, Vijayasree; Sugunan, Sankaran; Narayanan, Binitha N.

    2018-06-01

    In the present study, a green one-pot low-temperature method is adopted for the synthesis of a novel magnetic graphene nanocomposite catalyst. Graphene preparation is performed without employing any oxidizing agents or corrosive chemicals, under mild sonication in isopropyl alcohol - water mixture. Monolayered nanoplatelets of graphene are obtained in the green solvent mixture and the composite material is found to be ferromagnetic in nature, obvious from the vibrating sample magnetometric measurements. Fe in the nanocomposite exists in two different forms i.e., α-Fe2O3 and α-FeOOH, as evident from the material characterization results. The graphene nanocomposite is found to be highly efficient in the selective reduction of nitrobenzene to aniline under solvent free reaction conditions and magnetic separation of this fine nanomaterial from the reaction mixture is successfully carried out. The catalyst is efficiently reusable till five repeated cycles.

  17. Low temperature behaviour of elastomers in seals; Tieftemperaturverhalten von Elastomeren im Dichtungseinsatz

    Energy Technology Data Exchange (ETDEWEB)

    Jaunich, Matthias

    2012-04-25

    Elastomeric seals are of high importance as machine parts and construction elements, but in spite of this the low temperature limit for the use of a seal was not fully understood. Hence, the required safety relevant evaluation of the lowest acceptable operating seal temperature is difficult. Therefore the presented work was aimed to understand the temperature dependent material behaviour of representative elastomers and to conclude from this knowledge the low temperature limit down to which such seals could safely fulfil the desired requirements. Starting with the published statement that a seal can safely work below its glass transition temperature the influence of the glass-rubber-transition was investigated. At first the glass-rubber-transition temperatures of the selected elastomers were determined applying several techniques to allow a comparison with the behaviour of the seals during component tests. Furthermore a new method to characterise the low temperature behaviour of elastomers was developed that emulates the key features of the standardised compression set test used for seal materials. In comparison to the standardized test this new method allows a much faster measurement that can be automatically performed. Using a model based data analysis an extrapolation of the results to different temperatures can be performed and therefore the necessary measuring expenditure can be additionally reduced. For the temperature dependent characterisation of the failure process of real seals a measurement setup was designed and the materials behaviour was investigated. By use of the results of all applied characterisation techniques the observed dependence of the failure temperature on the degree of compression could be explained for the investigated seals under static load. Additionally information about the behaviour of such seals under dynamic load could be gained from the time dependent material behaviour by use of the time temperature superposition relationship

  18. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    XUJian; WEIWeisheng; 等

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  19. Atomically Precise Metal Nanoclusters for Catalytic Application

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Rongchao [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-11-18

    The central goal of this project is to explore the catalytic application of atomically precise gold nanoclusters. By solving the total structures of ligand-protected nanoclusters, we aim to correlate the catalytic properties of metal nanoclusters with their atomic/electronic structures. Such correlation unravel some fundamental aspects of nanocatalysis, such as the nature of particle size effect, origin of catalytic selectivity, particle-support interactions, the identification of catalytically active centers, etc. The well-defined nanocluster catalysts mediate the knowledge gap between single crystal model catalysts and real-world conventional nanocatalysts. These nanoclusters also hold great promise in catalyzing certain types of reactions with extraordinarily high selectivity. These aims are in line with the overall goals of the catalytic science and technology of DOE and advance the BES mission “to support fundamental research to understand, predict, and ultimately control matter and energy at the level of electrons, atoms, and molecules”. Our group has successfully prepared different sized, robust gold nanoclusters protected by thiolates, such as Au25(SR)18, Au28(SR)20, Au38(SR)24, Au99(SR)42, Au144(SR)60, etc. Some of these nanoclusters have been crystallographically characterized through X-ray crystallography. These ultrasmall nanoclusters (< 2 nm diameter) exhibit discrete electronic structures due to quantum size effect, as opposed to quasicontinuous band structure of conventional metal nanoparticles or bulk metals. The available atomic structures (metal core plus surface ligands) of nanoclusters serve as the basis for structure-property correlations. We have investigated the unique catalytic properties of nanoclusters (i.e. not observed in conventional nanogold catalysts) and revealed the structure-selectivity relationships. Highlights of our

  20. Effect of inlet temperature on the performance of a catalytic reactor. [air pollution control

    Science.gov (United States)

    Anderson, D. N.

    1978-01-01

    A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

  1. Catalyst Deactivation and Regeneration in Low Temperature Ethanol Steam Reforming with Rh/CeO2-ZrO2 Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Roh, Hyun-Seog; Platon, Alex; Wang, Yong; King, David L.

    2006-08-01

    Rh/CeO2-ZrO2 catalysts with various CeO2/ZrO2 ratios have been applied to H2 production from ethanol steam reforming at low temperatures. The catalysts all deactivated with time on stream (TOS) at 350 C. The addition of 0.5% K has a beneficial effect on catalyst stability, while 5% K has a negative effect on catalytic activity. The catalyst could be regenerated considerably even at ambient temperature and could recover its initial activity after regeneration above 200 C with 1% O2. The results are most consistent with catalyst deactivation due to carbonaceous deposition on the catalyst.

  2. The Low Temperature Microgravity Physics Experiments Project

    Science.gov (United States)

    Holmes, Warren; Lai, Anthony; Croonquist, Arvid; Chui, Talso; Eraker, J. H.; Abbott, Randy; Mills, Gary; Mohl, James; Craig, James; Balachandra, Balu; hide

    2000-01-01

    The Low Temperature Microgravity Physics Facility (LTMPF) is being developed by NASA to provide long duration low temperature and microgravity environment on the International Space Station (ISS) for performing fundamental physics investigations. Currently, six experiments have been selected for flight definition studies. More will be selected in a two-year cycle, through NASA Research Announcement. This program is managed under the Low Temperature Microgravity Physics Experiments Project Office at the Jet Propulsion Laboratory. The facility is being designed to launch and returned to earth on a variety of vehicles including the HII-A and the space shuttle. On orbit, the facility will be connected to the Exposed Facility on the Japanese Experiment Module, Kibo. Features of the facility include a cryostat capable of maintaining super-fluid helium at a temperature of 1.4 K for 5 months, resistance thermometer bridges, multi-stage thermal isolation system, thermometers capable of pico-Kelvin resolution, DC SQUID magnetometers, passive vibration isolation, and magnetic shields with a shielding factor of 80dB. The electronics and software architecture incorporates two VME buses run using the VxWorks operating system. Technically challenging areas in the design effort include the following: 1) A long cryogen life that survives several launch and test cycles without the need to replace support straps for the helium tank. 2) The minimization of heat generation in the sample stage caused by launch vibration 3) The design of compact and lightweight DC SQUID electronics. 4) The minimization of RF interference for the measurement of heat at pico-Watt level. 5) Light weighting of the magnetic shields. 6) Implementation of a modular and flexible electronics and software architecture. The first launch is scheduled for mid-2003, on an H-IIA Rocket Transfer Vehicle, out of the Tanegashima Space Center of Japan. Two identical facilities will be built. While one facility is onboard

  3. The Effect of Deposit Temperature on the Catalytic SO2-to-SO3 Conversion in a Copper Flash Smelting Heat Recovery Boiler

    Science.gov (United States)

    Lehmusto, Juho; Vainio, Emil; Laurén, Tor; Lindgren, Mari

    2018-02-01

    The aim of the work was to study the catalytic role of copper flash smelter deposit in the SO2-to-SO3 conversion. In addition, the effect of process gas temperature at 548 K to 1173 K (275 °C to 900 °C) on the amount of SO3 formed was addressed both in the absence and presence of genuine copper flash smelter deposit. The SO3 conversion rate changed as a function of process gas temperature, peaking at 1023 K (750 °C). A dramatic increase in the SO2-to-SO3 conversion was observed when process dust was present, clearly indicating that process dust catalyzes the SO2-to-SO3 conversion. Based on these results, the catalytic ability of the deposit may lead to sulfuric acid dew point corrosion.

  4. Production of phenolic-rich bio-oil from catalytic fast pyrolysis of biomass using magnetic solid base catalyst

    International Nuclear Information System (INIS)

    Zhang, Zhi-bo; Lu, Qiang; Ye, Xiao-ning; Li, Wen-tao; Hu, Bin; Dong, Chang-qing

    2015-01-01

    Highlights: • Phenolic-rich bio-oil was selectively produced from catalytic fast pyrolysis of biomass using magnetic solid base catalyst. • The actual yield of twelve major phenolic compounds reached 43.9 mg/g. • The peak area% of all phenolics reached 68.5% at the catalyst-to-biomass ratio of 7. • The potassium phosphate/ferroferric oxide catalyst possessed promising recycling properties. - Abstract: A magnetic solid base catalyst (potassium phosphate/ferroferric oxide) was prepared and used for catalytic fast pyrolysis of poplar wood to selectively produce phenolic-rich bio-oil. Pyrolysis–gas chromatography/mass spectrometry experiments were conducted to investigate the effects of pyrolysis temperature and catalyst-to-biomass ratio on the product distribution. The actual yields of important pyrolytic products were quantitatively determined by the external standard method. Moreover, recycling experiments were performed to determine the re-utilization abilities of the catalyst. The results showed that the catalyst exhibited promising activity to selectively produce phenolic-rich bio-oil, due to its capability of promoting the decomposition of lignin to generate phenolic compounds and meanwhile inhibiting the devolatilization of holocellulose. The maximal phenolic yield was obtained at the pyrolysis temperature of 400 °C and catalyst-to-biomass ratio of 2. The concentration of the phenolic compounds increased monotonically along with the increasing of the catalyst-to-biomass ratio, with the peak area% value increasing from 28.1% in the non-catalytic process to as high as 68.5% at the catalyst-to-biomass ratio of 7. The maximal total actual yield of twelve quantified major phenolic compounds was 43.9 mg/g, compared with the value of 29.0 mg/g in the non-catalytic process. In addition, the catalyst could be easily recovered and possessed promising recycling properties.

  5. High Selectively Catalytic Conversion of Lignin-Based Phenols into para-/m-Xylene over Pt/HZSM-5

    Directory of Open Access Journals (Sweden)

    Guozhu Liu

    2016-01-01

    Full Text Available High selectively catalytic conversion of lignin-based phenols (m-cresol, p-cresol, and guaiacol into para-/m-xylene was performed over Pt/HZSM-5 through hydrodeoxygenation and in situ methylation with methanol. It is found that the p-/m-xylene selectivity is uniformly higher than 21%, and even increase up to 33.5% for m-cresol (with phenols/methanol molar ratio of 1/8. The improved p-/m-xylene selectivity in presence of methanol is attributed to the combined reaction pathways: methylation of m-cresol into xylenols followed by HDO into p-/m-xylene, and HDO of m-cresol into toluene followed by methylation into p-/m-xylene. Comparison of the product distribution over a series of catalysts indicates that both metals and supporters have distinct effect on the p-/m-xylene selectivity.

  6. A new approach to inertise the containments during catalytic removal of hydrogen

    International Nuclear Information System (INIS)

    Chakraborty, A.K.; Markandeya, S.G.

    1994-01-01

    Use of catalytic recombiners for the removal of hydrogen during a severe accident has been recommended by the German Reactor Safety Commission (RSK) due to numerous successful demonstrations of their performances. At the early stages of the accident, a huge quantity of hydrogen is expected to be released in some compartments requiring supplementary measures to ensure that the excess hydrogen concentration wouldn't pose a threat of deflagration /1/. In this presentation a new idea based on catalytic removal of hydrogen with simultaneous passive inertisation of the atmosphere is proposed for large dry containments particularly for those compartments where high H 2 -concentrations are expected. During the catalytic oxidation of hydrogen, the large exothermic heat of reaction causes strong heating of the catalytic plates as well as a continuous energy input in the containment. This can be limited if this large heat energy is efficiently used for heating some chemical compounds to release inert gases such as steam and/or CO 2 by dissociation at moderate temperatures. Such compounds can be arranged in the form of thin slabs in good thermal contact with the catalytic plates. Several such compounds have been identified which are capable of releasing steam and CO 2 equivalent to about 40 - 75% of their mass. Preliminary calculations have been carded out to demonstrate the effectiveness of the proposed concept for the case of two such selected chemicals placed adjacent to the catalytic plate type recombiners. The calculations performed show promising results. (author)

  7. Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis.

    Science.gov (United States)

    Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

    2017-11-01

    Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. PdNP Decoration of Halloysite Lumen via Selective Grafting of Ionic Liquid onto the Aluminol Surfaces and Catalytic Application.

    Science.gov (United States)

    Dedzo, Gustave K; Ngnie, Gaëlle; Detellier, Christian

    2016-02-01

    The synthesis of selectively deposited palladium nanoparticles (PdNPs) inside tubular halloysite lumens is reported. This specific localization was directed by the selective modification of the aluminol surfaces of the clay mineral through stable Al-O-C bonds. An ionic liquid (1-(2-hydroxyethyl)-3-methylimidazolium) was grafted onto halloysite following the guest displacement method (generally used for kaolinite) using halloysite-DMSO preintercalate. The characterization of this clay nanohybrid material (XRD, NMR, TGA) showed characteristics reminiscent of similar materials synthesized from kaolinite. The grafting on halloysite lumens was also effective without using the DMSO preintercalate. The presence of these new functionalities in halloysite directs the synthesis of uniform PdNPs with size ranging between 3 and 6 nm located exclusively in the lumens. This results from the selective adsorption of PdNPs precursors in functionalized lumens through an anion exchange mechanism followed by in situ reduction. In contrast, the unmodified clay mineral displayed nanoparticles both inside and outside the tubes. These catalysts showed significant catalytic activity for the reduction of 4-nitrophenol (4-NP). The most efficient catalysts were recycled up to three times without reducing significantly the catalytic activities.

  9. Combustion, performance, and selective catalytic reduction of NOx for a diesel engine operated with combined tri fuel (H_2, CH_4, and conventional diesel)

    International Nuclear Information System (INIS)

    Abu-Jrai, Ahmad M.; Al-Muhtaseb, Ala'a H.; Hasan, Ahmad O.

    2017-01-01

    In this study, the effect of tri fuel (ULSD, H_2, and CH_4) operation under real exhaust gas conditions with different gaseous fuel compositions on the combustion characteristics, engine emissions, and selective catalytic reduction (SCR) after treatment was examined at low, medium, and high engine loads. Pt/Al_2O_3-SCR reactor was used and operated at different exhaust gas temperatures. Results revealed that at low load, the two gaseous fuels (H_2 and CH_4) have the same trend on combustion proccess, where both reduce the in-cylinder pressure and rate of heat release. At the high engine load there was a considerable influence appeared as an increase of the premixed combustion phase and a significant decrease of the total combustion duration. In terms of emissions, it was observed that at high engine load, fuels with high CH_4 content tend to reduce NOx formation, whereas, fuels with high H_2 content tend to reduce PM formation, moreover, combustion of tri fuel with 50:50 fuel mixture resulted in lower BSFC compared to the other ratios and hence, the best engine efficiency. The hydrocarbon-SCR catalyst has shown satisfactory performance in NOx reduction under real diesel exhaust gas in a temperature window of 180–280 °C for all engine loads. - Highlights: • Effect of tri fuel (ULSD, H_2, CH_4) on combustion and engine emissions was examined. • Fuel with high CH_4 content (H50-M50 and H25-M75) tend to reduce NOx formation. • Fuel with high H_2 content (H75-M25 and H50-M50) tend to reduce PM formation. • Increasing the percentage of H_2 in the feed gas improved the NO_x reduction. • The hydrocarbon-SCR catalyst has shown satisfactory performance in NO_x reduction.

  10. Catalytic decomposition of tar derived from wood waste pyrolysis using Indonesian low grade iron ore as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Wicakso, Doni Rahmat [Chemical Engineering Department, Faculty of Engineering, Lambung Mangkurat University, Jalan A. Yani KM. 36 Banjarbaru, 70714, South Kalimantan (Indonesia); Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Sutijan; Rochmadi [Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Budiman, Arief, E-mail: abudiman@ugm.ac.id [Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Center for Energy Studies, Gadjah Mada University, Sekip K1A, Yogyakarta, 55281 (Indonesia)

    2016-06-03

    Low grade iron ore can be used as an alternative catalyst for bio-tar decomposition. Compared to other catalysts, such as Ni, Rd, Ru, Pd and Pt, iron ore is cheaper. The objective of this research was to investigate the effect of using low grade iron ore as catalyst for tar catalytic decomposition in fixed bed reactor. Tar used in this experiment was pyrolysis product of wood waste while the catalyst was Indonesian low grade iron ore. The variables studied were temperatures between 500 – 600 °C and catalyst weight between 0 – 40 gram. The first step, tar was evaporated at 450 °C to produce tar vapor. Then, tar vapor was flowed to fixed bed reactor filled low grade iron ore. Gas and tar vapor from reactor was cooled, then the liquid and uncondensable gas were analyzed by GC/MS. The catalyst, after experiment, was weighed to calculate total carbon deposited into catalyst pores. The results showed that the tar components that were heavy and light hydrocarbon were decomposed and cracked within the iron ore pores to from gases, light hydrocarbon (bio-oil) and carbon, thus decreasing content tar in bio-oil and increasing the total gas product. In conclusion, the more low grade iron ore used as catalyst, the tar content in the liquid decrease, the H{sup 2} productivity increased and calorimetric value of bio-oil increased.

  11. Fischer–Tropsch Synthesis at a Low Pressure on Subnanometer Cobalt Oxide Clusters: The Effect of Cluster Size and Support on Activity and Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungsik; Lee, Byeongdu; Seifert, Sönke; Winans, Randall E.; Vajda, Stefan

    2015-05-21

    In this study, the catalytic activity and changes in the oxidation state during the Fischer Tropsch (FT) reaction was investigated on subnanometer size-selected cobalt clusters deposited on oxide (Al2O3, MgO) and carbon-based (ultrananocrystalline diamond UNCD) supports by temperature programmed reaction (TPRx) combined with in-situ grazing-incidence X-ray absorption characterization (GIXAS). The activity and selectivity of ultrasmall cobalt clusters exhibits a very strong dependence on cluster size and support. The evolution of the oxidation state of metal cluster during the reaction reveals that metal-support interaction plays a key role in the reaction.

  12. Sensors based on mesoporous SnO{sub 2}-CuWO{sub 4} with high selective sensitivity to H{sub 2}S at low operating temperature

    Energy Technology Data Exchange (ETDEWEB)

    Stanoiu, Adelina; Simion, Cristian E. [National Institute of Materials Physics, Atomistilor 405A, P.O. Box MG-7, 077125 Bucharest, Măgurele (Romania); Calderon-Moreno, Jose Maria; Osiceanu, Petre [“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, Surface Chemistry and Catalysis Laboratory, Spl. Independentei 202, 060021, Bucharest (Romania); Florea, Mihaela [University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, B-dul Regina Elisabeta 4-12, Bucharest (Romania); National Institute of Materials Physics, Atomistilor 405A, P.O. Box MG-7, 077125 Bucharest, Măgurele (Romania); Teodorescu, Valentin S. [National Institute of Materials Physics, Atomistilor 405A, P.O. Box MG-7, 077125 Bucharest, Măgurele (Romania); Somacescu, Simona, E-mail: somacescu.simona@gmail.com [“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, Surface Chemistry and Catalysis Laboratory, Spl. Independentei 202, 060021, Bucharest (Romania)

    2017-06-05

    Highlights: • Mesoporous SnO{sub 2}-CuWO{sub 4} obtained by an inexpensive synthesis route. • Powders characterization performed by a variety of complementary techniques. • SnO{sub 2}-CuWO{sub 4} layers with high selective sensitivity to H{sub 2}S. • Low operating temperature and relative humidity influences. - Abstract: Development of new sensitive materials by different synthesis routes in order to emphasize the sensing properties for hazardous H{sub 2}S detection is one of a nowadays challenge in the field of gas sensors. In this study we obtained mesoporous SnO{sub 2}-CuWO{sub 4} with selective sensitivity to H{sub 2}S by an inexpensive synthesis route with low environmental pollution level, using tripropylamine (TPA) as template and polyvinylpyrrolidone (PVP) as dispersant/stabilizer. In order to bring insights about the intrinsic properties, the powders were characterized by means of a variety of complementary techniques such as: X-Ray Diffraction, XRD; Transmission Electron Microscopy, TEM; High Resolution TEM, HRTEM; Raman Spectroscopy, RS; Porosity Analysis by N{sub 2} adsorption/desorption, BET; Scanning Electron Microscopy, SEM and X-ray Photoelectron Spectroscopy, XPS. The sensors were fabricated by powders deposition via screen-printing technique onto planar commercial Al{sub 2}O{sub 3} substrates. The sensor signals towards H{sub 2}S exposure at low operating temperature (100 °C) reaches values from 10{sup 5} (for SnWCu600) to 10{sup 6} (for SnWCu800) over the full range of concentrations (5–30 ppm). The recovery processes were induced by a short temperature trigger of 500 °C. The selective sensitivity was underlined with respect to the H{sub 2}S, relative to other potential pollutants and relative humidity (10–70% RH).

  13. Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

    International Nuclear Information System (INIS)

    Park, Young Ok; Choi, Ho Kyung

    2010-01-01

    The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

  14. Catalytic properties of new anode materials for solid oxide fuel cells operated under methane at intermediary temperature

    Science.gov (United States)

    Sauvet, A.-L.; Fouletier, J.

    The recent trend in solid oxide fuel cell concerns the use of natural gas as fuel. Steam reforming of methane is a well-established process for producing hydrogen directly at the anode side. In order to develop new anode materials, the catalytic activities of several oxides for the steam reforming of methane were characterized by gas chromatography. We studied the catalytic activity as a function of steam/carbon ratios r. The methane and the steam content were varied between 5 and 30% and between 1.5 and 3.5%, respectively, corresponding to r-values between 0.07 and 0.7. Catalyst (ruthenium and vanadium)-doped lanthanum chromites substituted with strontium, gadolinium-doped ceria (Ce 0.9Gd 0.1O 2) referred as to CeGdO 2, praseodymium oxide, molybdenum oxide and copper oxide were tested. The working temperature was fixed at 850°C, except for 5% ruthenium-doped La 1- xSr xCrO 3 where the temperature was varied between 700 and 850°C. Two types of behavior were observed as a function of the activity of the catalyst. The higher steam reforming efficiency was observed with 5% of ruthenium above 750°C.

  15. Treatment of the early-stage glottic cancer using low-temperature radiofrequency coblation

    Directory of Open Access Journals (Sweden)

    Bing Liu

    2016-01-01

    Conclusions: Although the current probe design has limitations for the resection of certain tumors, low-temperature RF coblation appears to be a potentially effective method for the endoscopic resection of selected glottic cancers.

  16. Sintering of Catalytic Nanoparticles: Particle Migration or Ostwald Ripening?

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; DeLaRiva, Andrew T.; Challa, Sivakumar R.

    2013-01-01

    deactivation, is an important mechanism for the loss of catalyst activity. This is especially true for high temperature catalytic processes, such as steam reforming, automotive exhaust treatment, or catalytic combustion. With dwindling supplies of precious metals and increasing demand, fundamental...

  17. Selective carbon monoxide oxidation over Ag-based composite oxides

    Energy Technology Data Exchange (ETDEWEB)

    Guldur, C. [Gazi University, Ankara (Turkey). Chemical Engineering Department; Balikci, F. [Gazi University, Ankara (Turkey). Institute of Science and Technology, Environmental Science Department

    2002-02-01

    We report our results of the synthesis of 1 : 1 molar ratio of the silver cobalt and silver manganese composite oxide catalysts to remove carbon monoxide from hydrogen-rich fuels by the catalytic oxidation reaction. Catalysts were synthesized by the co-precipitation method. XRD, BET, TGA, catalytic activity and catalyst deactivation studies were used to identify active catalysts. Both CO oxidation and selective CO oxidation were carried out in a microreactor using a reaction gas mixture of 1 vol% CO in air and another gas mixture was prepared by mixing 1 vol% CO, 2 vol% O{sub 2}, 84 vol% H{sub 2}, the balance being He. 15 vol% CO{sub 2} was added to the reactant gas mixture in order to determine the effect of CO{sub 2}, reaction gases were passed through the humidifier to determine the effect of the water vapor on the oxidation reaction. It was demonstrated that metal oxide base was decomposed to the metallic phase and surface areas of the catalysts were decreased when the calcination temperature increased from 200{sup o}C to 500{sup o}C. Ag/Co composite oxide catalyst calcined at 200{sup o}C gave good activity at low temperatures and 90% of CO conversion at 180{sup o}C was obtained for the selective CO oxidation reaction. The addition of the impurities (CO{sub 2} or H{sub 2}O) decreased the activity of catalyst for selective CO oxidation in order to get highly rich hydrogen fuels. (author)

  18. Catalytic membrane in reduction of aqueous nitrates: operational principles and catalytic performance

    NARCIS (Netherlands)

    Ilinitch, O.M.; Cuperus, F.P.; Nosova, L.V.; Gribov, E.N.

    2000-01-01

    The catalytic membrane with palladium-copper active component supported over the macroporous ceramic membrane, and a series of γ-Al 2O 3 supported Pd-Cu catalysts were prepared and investigated. In reduction of nitrate ions by hydrogen in water at ambient temperature, pronounced internal diffusion

  19. Power generation from low-temperature heat source

    Energy Technology Data Exchange (ETDEWEB)

    Lakew, Amlaku Abie

    2012-07-01

    The potential of low-temperature heat sources for power production has been discussed for decades. The diversity and availability of low-temperature heat sources makes it interesting for power production. The thermodynamic power cycle is one of the promising technologies to produce electricity from low-temperature heat sources. There are different working fluids to be used in a thermodynamic power cycle. Working fluid selection is essential for the performance of the power cycle. Over the last years, different working fluid screening criteria have been used. In broad speaking the screening criteria can be grouped as thermodynamic performance, component size requirement, economic performance, safety and environmental impact. Screening of working fluids at different heat source temperatures (80-200 Celsius degrees) using thermodynamic performance (power output and exergy efficiency) and component size (heat exchanger and turbine) is investigated. It is found that the 'best' working fluid depends on the criteria used and heat source temperature level. Transcritical power cycles using carbon dioxide as a working fluid is studied to produce power at 100 Celsius degrees. Carbon dioxide is an environmentally friendly refrigerant. The global warming potential of carbon dioxide is 1. Furthermore, because of its low critical temperature (31 Celsius degrees), carbon dioxide can operate in a transcritical power cycle for lower heat source temperatures. A transcritical configuration avoids the problem of pinching which otherwise would happened in subcritical power cycle. In the process, better temperature matching is achieved and more heat is extracted. Thermodynamic analysis of transcritical cycle is performed; it is found that there is an optimal operating pressure for highest net power output. The pump work is a sizable fraction of the work produced by the turbine. The effect of efficiency deterioration of the pump and the turbine is compared. When the

  20. Low-temperature conversion of ammonia to nitrogen in water with ozone over composite metal oxide catalyst.

    Science.gov (United States)

    Chen, Yunnen; Wu, Ye; Liu, Chen; Guo, Lin; Nie, Jinxia; Chen, Yu; Qiu, Tingsheng

    2018-04-01

    As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people's attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co 3 O 4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia (50mg/L) in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co 3 O 4 molar ratio 8:2, calcined at 500°C for 3hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of 44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO 4 2- and HCO 3 - could inhibit the catalytic activity while CO 3 2- and Br - could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia. Copyright © 2017. Published by Elsevier B.V.

  1. Catalytic fast co-pyrolysis of bamboo residual and waste lubricating oil over an ex-situ dual catalytic beds of MgO and HZSM-5: Analytical PY-GC/MS study

    International Nuclear Information System (INIS)

    Wang, Jia; Zhang, Bo; Zhong, Zhaoping; Ding, Kuan; Deng, Aidong; Min, Min; Chen, Paul; Ruan, Roger

    2017-01-01

    Highlights: • Catalytic co-pyrolysis of bamboo residual and waste lubricating oil was conducted. • MgO was beneficial to deacidification via ketonization and aldol condensation. • Dual catalytic bed system exhibited prominent deoxygenation and aromatization. • A HZSM-5/MgO mass ratio of 3:2 largely increased the yield of aromatics. • Waste lubricating oil leads hydrocarbon pool towards the formation of hydrocarbons. - Abstract: Catalytic fast co-pyrolysis (co-CFP) of bamboo residual (BR) and waste lubricating oil (WLO) over dual catalytic beds of MgO and HZSM-5 were carried out in an analytical PY-GC/MS. The effects of pyrolysis temperature, catalyst types, HZSM-5/MgO mass ratio and WLO percentage on products distribution and selectivities of aromatics were investigated. Experimental results revealed that 600 °C promoted the total peak area of volatile matters and accelerated the yields of furans and phenols. Compared to HZSM-5, MgO exhibited pronounced deacidification via ketonization and aldol condensation reactions as the minimum yield of acids (2.116%) and the maximum yield of ketones (28.805%) could be obtained. Furthermore, given the selectivity of phenols, MgO not only spurred the increase of overall phenols yield, but also facilitated the selectivity of light phenols like phenol and 4-methyl-phenol. With respect to the co-CFP of BR and WLO, a HZSM-5/MgO mass ratio of 3:2 largely accelerated the yield of aromatics via Diels-Alder reaction. Simultaneously, the WLO percentage played a vital role in the yield of hydrocarbons (i.e. aromatics + olefins & alkanes), and the maximum yield (70.305%) could be attained at the percentage of 60% as a function of significant activation of hydrocarbon pool.

  2. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Alcinikov, Y.; Fainberg, V.; Garbar, A.; Gutman, M.; Hetsroni, G.; Shindler, Y.; Tatrtakovsky, L.; Zvirin, Y.

    1998-01-01

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  3. Circadian rhythm of temperature selection in a nocturnal lizard.

    Science.gov (United States)

    Refinetti, R; Susalka, S J

    1997-08-01

    We recorded body temperature and locomotor activity of Tokay geckos (Gekko gecko) with free access to a heat source under a 14:10 light-dark cycle and in constant darkness. Under the light-dark cycle, the lizards selected higher temperatures during the light phase, when locomotor activity was less intense. Rhythmicity in temperature selection was transiently disrupted but later resumed when the animals were placed in constant darkness. These results demonstrate the existence of a circadian rhythm of temperature selection in nocturnal ectotherms and extend previous findings of a temporal mismatch between the rhythms of locomotor activity and temperature selection in nocturnal rodents.

  4. Nonvacuum, maskless fabrication of a flexible metal grid transparent conductor by low-temperature selective laser sintering of nanoparticle ink.

    Science.gov (United States)

    Hong, Sukjoon; Yeo, Junyeob; Kim, Gunho; Kim, Dongkyu; Lee, Habeom; Kwon, Jinhyeong; Lee, Hyungman; Lee, Phillip; Ko, Seung Hwan

    2013-06-25

    We introduce a facile approach to fabricate a metallic grid transparent conductor on a flexible substrate using selective laser sintering of metal nanoparticle ink. The metallic grid transparent conductors with high transmittance (>85%) and low sheet resistance (30 Ω/sq) are readily produced on glass and polymer substrates at large scale without any vacuum or high-temperature environment. Being a maskless direct writing method, the shape and the parameters of the grid can be easily changed by CAD data. The resultant metallic grid also showed a superior stability in terms of adhesion and bending. This transparent conductor is further applied to the touch screen panel, and it is confirmed that the final device operates firmly under continuous mechanical stress.

  5. Achieving low return temperature for domestic hot water preparation by ultra-low-temperature district heating

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Svendsen, Svend

    2017-01-01

    District heating (DH) is a cost-effective method of heat supply, especially to area with high heat density. Ultra-low-temperature district heating (ULTDH) is defined with supply temperature at 35-45 degrees C. It aims at making utmost use of the available low-temperature energy sources. In order...... to achieve high efficiency of the ULTDH system, the return temperature should be as low as possible. For the energy-efficient buildings in the future, it is feasible to use ULTDH to cover the space heating demand. However, considering the comfort and hygiene requirements of domestic hot water (DHW...... lower return temperature and higher efficiency for DHW supply, an innovative substation was devised, which replaced the bypass with an instantaneous heat exchanger and a micro electric storage tank. The energy performance of the proposed substation and the resulting benefits for the DH system...

  6. Catalytical conversion from ortho-H2 to para-H2

    International Nuclear Information System (INIS)

    Corat, E.J.

    1984-01-01

    The classical theory of ortho to para-H 2 conversion is discussed, considering the catalytical action of an inhomogeneous magnetic field on a surface with magnetic particles. In particular, the use of charcoal as a catalyst at low temperatures (77 0 K) is considered and some results are presented. The development of a sensor for the determination of para-H 2 concentration in H 2 gas is studied. Experimental results with this sensor are also shown. (Author) [pt

  7. Experimental and Numerical Study of Low Temperature Methane Steam Reforming for Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Martin Khzouz

    2017-12-01

    Full Text Available Low temperature methane steam reforming for hydrogen production, using experimental developed Ni/Al2O3 catalysts is studied both experimentally and numerically. The catalytic activity measurements were performed at a temperature range of 500–700 °C with steam to carbon ratio (S/C of 2 and 3 under atmospheric pressure conditions. A mathematical analysis to evaluate the reaction feasibility at all different conditions that have been applied by using chemical equilibrium with applications (CEA software and in addition, a mathematical model focused on the kinetics and the thermodynamics of the reforming reaction is introduced and applied using a commercial finite element analysis software (COMSOL Multiphysics 5.0. The experimental results were employed to validate the extracted simulation data based on the yields of the produced H2, CO2 and CO at different temperatures. A maximum hydrogen yield of 2.7 mol/mol-CH4 is achieved at 700 °C and S/C of 2 and 3. The stability of the 10%Ni/Al2O3 catalyst shows that the catalyst is prone to deactivation as supported by Thermogravimetric Analysis TGA results.

  8. Catalytic reduction of NOx in gasoline engine exhaust over copper- and nickel-exchanged X-zeolite catalysts

    International Nuclear Information System (INIS)

    Bhattacharyya, S.; Das, R.K.

    2001-01-01

    Catalytic removal of NO x in engine exhaust gases can be accomplished by non-selective reduction, selective reduction and decomposition. Noble metals are extensively used for non-selective reduction of NO x and up to 90% of engine NO x emissions can be reduced in a stoichiometric exhaust. This requirement of having the stoichiometric fuel-air ratio acts against efficiency improvement of engines. Selective NO x reduction in the presence of different reductants such as, NH 3 , urea or hydrocarbons, requires close control of the amount of reductant being injected which otherwise may be emitted as a pollutant. Catalytic decomposition is the best option for NO x removal. Nevertheless, catalysts which are durable, economic and active for NO x reduction at normal engine exhaust temperature ranges are still being investigated. Three catalysts based on X-zeolite have been developed by exchanging the Na+ ion with copper, nickel and copper-nickel metal ions and applied to the exhaust of a stationary gasoline engine to explore their potential for catalytic reduction of NO x under a wide range of engine and exhaust conditions. Some encouraging results have been obtained. The catalyst Cu-X exhibits much better NO x reduction performance at any temperature in comparison to Cu-Ni-X and Ni-X; while Cu-Ni-X catalyst exhibits slightly better performance than Ni-X catalyst. Maximum NO x efficiency achieved with Cu-X catalyst is 59.2% at a space velocity (sv) of 31 000 h -1 ; while for Cu-Ni-X and Ni-X catalysts the equivalent numbers are 60.4% and 56% respectively at a sv of 22 000 h -1 . Unlike noble metals, the doped X-zeolite catalysts exhibit significant NO x reduction capability for a wide range of air/fuel ratio and with a slower rate of decline as well with increase in air/fuel ratio. (author)

  9. Pyroelectrically Induced Pyro-Electro-Chemical Catalytic Activity of BaTiO3 Nanofibers under Room-Temperature Cold–Hot Cycle Excitations

    Directory of Open Access Journals (Sweden)

    Yuntao Xia

    2017-04-01

    Full Text Available A pyro-electro-chemical catalytic dye decomposition using lead-free BaTiO3 nanofibers was realized under room-temperature cold–hot cycle excitation (30–47 °C with a high Rhodamine B (RhB decomposition efficiency ~99%, which should be ascribed to the product of pyro-electric effect and electrochemical redox reaction. Furthermore, the existence of intermediate product of hydroxyl radical in pyro-electro-chemical catalytic process was also observed. There is no significant decrease in pyro-electro-chemical catalysis activity after being recycled five times. The pyro-electrically induced pyro-electro-chemical catalysis provides a high-efficient, reusable and environmentally friendly technology to remove organic pollutants from water.

  10. Enhancing charge transfer kinetics by nanoscale catalytic cermet interlayer.

    Science.gov (United States)

    An, Jihwan; Kim, Young-Beom; Gür, Turgut M; Prinz, Fritz B

    2012-12-01

    Enhancing the density of catalytic sites is crucial for improving the performance of energy conversion devices. This work demonstrates the kinetic role of 2 nm thin YSZ/Pt cermet layers on enhancing the oxygen reduction kinetics for low temperature solid oxide fuel cells. Cermet layers were deposited between the porous Pt cathode and the dense YSZ electrolyte wafer using atomic layer deposition (ALD). Not only the catalytic role of the cermet layer itself but the mixing effect in the cermet was explored. For cells with unmixed and fully mixed cermet interlayers, the maximum power density was enhanced by a factor of 1.5 and 1.8 at 400 °C, and by 2.3 and 2.7 at 450 °C, respectively, when compared to control cells with no cermet interlayer. The observed enhancement in cell performance is believed to be due to the increased triple phase boundary (TPB) density in the cermet interlayer. We also believe that the sustained kinetics for the fully mixed cermet layer sample stems from better thermal stability of Pt islands separated by the ALD YSZ matrix, which helped to maintain the high-density TPBs even at elevated temperature.

  11. Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

    Science.gov (United States)

    Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

    2010-04-07

    The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

  12. The influence of calcination temperatures on the acid-based properties and catalytic activity for the 1,3-butadiene synthesis from ethanol/acetaldehyde mixture

    Science.gov (United States)

    Gao, Meixiang; Jiang, Haoxi; Zhang, Minhua

    2018-05-01

    The influences of the calcination temperature on the catalysts' acid-based properties and catalytic activity for the 1,3-butadiene synthesis from ethanol are investigated. The results show that the 2 wt% ZrO2/Nano-SiO2 calcined at 773 K shows the best performance with the selectivity of 93.18% and conversion of 58.52% when reacted at 593 K, a WHSV of 1.8 h-1 and 3.5:1 volume ratio ethanol-to-acetaldehyde in an atmospheric fixed-bed reactor. Prepared catalysts were characterized by N2 adsorption-desorption, XRD, temperature-programmed desorption of NH3 and CO2, FTIR spectroscopy of adsorbed pyridine and CO2. Based on the relationship between the catalyst activity and its properties, the fact can be presumed that the formation and strength of Zrsbnd Osbnd Si bond determines the acid-based properties of the catalyst. In addition, moderate-intensity weak acid-basic sites are more suitable for ethanol conversion to BD with the amount of acid and basic sites as close as possible.

  13. Research progress on catalytic denitrification technology in chemical industry

    Science.gov (United States)

    Jin, Yezhi

    2017-12-01

    In recent years, due to the rising emission of NOx annually, attention has been aroused widely by people on more and more severe environmental problems. This paper first discusses applying NOx removal and control technologies and relating chemical principles. Of many technologies, selective reduction reaction (SCR) is the most widely used. Catalysts, the concentration of NOx at the entrance of SCR catalytic reactor, reaction temperature, NH3/NOx mole ratio and NH3 slip rate analyzed later contributes to the removal efficiency of NOx. Finally, the processing and configuration of SCR de-NOx system are briefly introduced.

  14. Catalytic cracking of iso-hexene over sapo-34 catalyst

    International Nuclear Information System (INIS)

    Nawaz, Z.; Shu, Q.

    2009-01-01

    The catalytic cracking of model feed compound, iso-hexene (2-methyl-1-pentene) was experimentally studied over 100% pure SAPO-34 zeolite catalyst. The critical focus was given to obtain maximum propylene selectivity. The product distributions were analyzed at temperature between 450-600 degree C. time-on-stream (TOS) from 1 to 5 min. and at WHSV = 7.9 h/sub -1/ The reaction behavior was quantified on both direct and indirect carbenium ion mechanisms owing to catalyst's small pore diameter with respect to 2-methyl-l-pentene kinetic diameter. The propylene yield and selectivity obtained was 41.2% and 43.1% respectively. with higher overall olefins selectivity 90.3%. The small pore size and week surface acid sites of 1000 percent pure SAPO-34 catalyst were found to be suitable for light olefins production and eliminate chances of bimolecular reactions. It was observed that both conversion and selectivity were strongly effected by TOS, as coke precursors become dominant and deactivate catalyst at higher TOS. (author)

  15. Monolithic Au/CeO2 nanorod framework catalyst prepared by dealloying for low-temperature CO oxidation

    Science.gov (United States)

    Zhang, Xiaolong; Duan, Dong; Li, Guijing; Feng, Wenjie; Yang, Sen; Sun, Zhanbo

    2018-03-01

    Monolithic Au/CeO2 nanorod frameworks (NFs) with porous structure were prepared by dealloying melt-spun Al89.7Ce10Au0.3 ribbons. After calcination in O2, a 3D Au/CeO2 NF catalyst with large surface area was obtained and used for low-temperature CO oxidation. The small Au clusters/nanoparticles (NPs) were in situ supported and highly dispersed on the nanorod surface, creating many nanoscale contact interfaces. XPS results demonstrated that high-concentration oxygen vacancy and Au δ+/Au0 co-existed in the calcined sample. The Au/CeO2 nanorod catalyst calcined at 400 °C exhibited much higher catalytic activity for CO oxidation compared with the dealloyed sample and bare CeO2 nanorods. Moreover, its complete reaction temperature was as low as 91 °C. The designed Au/CeO2 NF catalyst not only possessed extreme sintering resistance but also exhibited high performance owing to the enhanced interaction between the Au clusters/NPs and CeO2 nanorod during calcination.

  16. Spectroscopic investigation into the design of solid-acid catalysts for the low temperature dehydration of ethanol.

    Science.gov (United States)

    Potter, Matthew E; Aswegen, Sivan V; Gibson, Emma K; Silverwood, Ian P; Raja, Robert

    2016-07-14

    The increased demand for bulk hydrocarbons necessitates research into increasingly sustainable, energy-efficient catalytic processes. Owing to intricately designed structure-property correlations, SAPO-34 has become established as a promising material for the low temperature ethanol dehydration to produce ethylene. However, further optimization of this process requires a precise knowledge of the reaction mechanism at a molecular level. In order to achieve this a range of spectroscopic characterization techniques are required to probe both the interaction with the active site, and also the wider role of the framework. To this end we employ a combination of in situ infra-red and neutron scattering techniques to elucidate the influence of the surface ethoxy species in the activation of both diethyl ether and ethanol, towards the improved formation of ethylene at low temperatures. The combined conclusions of these studies is that the formation of ethylene is the rate determining step, which is of fundamental importance towards the development of this process and the introduction of bio-ethanol as a viable feedstock for ethylene production.

  17. The influence of calcination temperature on catalytic activities in a Co based catalyst for CO2 dry reforming

    International Nuclear Information System (INIS)

    Song, Sang-Hoon; Son, Ju-Hee; Budiman, Anatta Wahyu; Choi, Myoung-Jae; Chang, Tae-Sun; Shin, Chae-Ho

    2014-01-01

    The carbon dioxide dry reforming of methane (CDR) reaction could be thermodynamically favored in the range of 800 to 1,000 .deg. C. However, the catalyst in this reaction should be avoided at the calcination temperature over 800 .deg. C since strong metal support interaction (SMSI) in this temperature range can decrease activity due to loss of active sites. Therefore, we focused on optimizing the temperature of pretreatment and a comparison of surface characterization results for CDR. Results related to metal sintering over support, re-dispersion by changing of particle size of metal-support, and strong metal support interaction were observed and confirmed in this work. In our conclusion, optimum calcination temperature for a preparation of catalyst was proposed that 400 .deg. C showed a higher and more stable catalytic activity without changing of support characteristics

  18. Highly anisotropic SmCo5 nanoflakes by surfactant-assisted ball milling at low temperature

    International Nuclear Information System (INIS)

    Liu, Lidong; Zhang, Songlin; Zhang, Jian; Ping Liu, J.; Xia, Weixing; Du, Juan; Yan, Aru; Yi, Jianhong; Li, Wei; Guo, Zhaohui

    2015-01-01

    Surfactant-assisted ball milling (SABM) has been shown to be a promising method for preparing rare earth-transition metal (RE-TM) nanoflakes and nanoparticles. In this work, we prepared SmCo 5 nanoflakes by SABM at low temperature, and 2-methyl pentane and trioctylamine were specially selected as solvent and surfactant, respectively, due to their low melting points. The effects of milling temperature on the morphology, microstructure and magnetic performance of SmCo 5 nanoflakes were investigated systematically. Comparing with the samples milled at room temperature, the SmCo 5 nanoflakes prepared at low temperature displayed more homogeneous morphology and lower oxygen content. Remarkably, better crystallinity, better grain alignment and larger remanence ratio were shown in the samples milled at low temperature, which resulted from the distinct microstructure caused by low milling temperature. The differences in structural evolution between the SmCo 5 nanoflakes milled at room temperature and low temperature, including the formation of nanocrystalline, grain boundary sliding, grain rotation, et al., were discussed. It was found that lowering the temperature of SABM was a powerful method for the fabrication of RE-TM nanoflakes, which showed better hard magnetic properties and lower oxygen content. This was important for the preparation of high-performance sintered magnets, bonded magnets and nanocomposite magnets. - Highlights: • We prepare SmCo 5 nanoflakes by surfactant-assisted ball milling at low temperature. • Better grain alignment and higher remanence ratio are achieved. • The oxygen content is reduced by lowering the milling temperature. • A distinct microstructural evolution caused by low milling temperature is clarified

  19. Low temperature and surfactant-free synthesis of Pd2Sn intermetallic nanoparticles for ethanol electro-oxidation

    International Nuclear Information System (INIS)

    Wang, Congmin; Wu, Yurong; Wang, Xin; Zou, Liangliang; Zou, Zhiqing; Yang, Hui

    2016-01-01

    Many intermetallic compounds have a predictable structure, interesting electronic effects, and useful catalytic properties. In this work, a low temperature, surfactant-free, and one-pot method is used to synthesize carbon supported Pd 2 Sn intermetallic nanoparticles. The superlattice of the product was then characterized using X-ray diffraction and transmission electron microscopy. These synthesized intermetallic nanoparticles were found to exhibit a higher activity and stability for electrocatalysis of the ethanol oxidation reaction in an alkaline media than has been achieved using a traditional Pd/C catalyst, which could be attributed to the structural and compositional stabilities of ordered Pd 2 Sn intermetallic nanoparticles.

  20. A general framework to select working fluid and configuration of ORCs for low-to-medium temperature heat sources

    International Nuclear Information System (INIS)

    Vivian, Jacopo; Manente, Giovanni; Lazzaretto, Andrea

    2015-01-01

    Highlights: • General guidelines are proposed to select ORC working fluid and cycle layout. • Distance between critical and heat source temperature for optimal fluid selection. • Separate contributions of cycle efficiency and heat recovery factor. - Abstract: The selection of the most suitable working fluid and cycle configuration for a given heat source is a fundamental step in the search for the optimum design of Organic Rankine Cycles. In this phase cycle efficiency and heat source recovery factor lead to opposite design choices in the achievement of maximum system efficiency and, in turn, maximum power output. In this work, both separate and combined effects of these two performance factors are considered to supply a thorough understanding of the compromise resulting in maximum performance. This goal is pursued by carrying out design optimizations of four different ORC configurations operating with twenty-seven working fluids and recovering heat from sensible heat sources in the temperature range 120–180 °C. Optimum working fluids and thermodynamic parameters are those which simultaneously allow high cycle efficiency and high heat recovery from the heat source to be obtained. General guidelines are suggested to reach this target for any system configuration. The distance between fluid critical temperature and inlet temperature of the heat source is found to play a key role in predicting the optimum performance of all system configurations regardless of the inlet temperature of the heat source

  1. Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH_3

    International Nuclear Information System (INIS)

    Zhang, Tao; Shi, Juan; Liu, Jian; Wang, Daxi; Zhao, Zhen; Cheng, Kai; Li, Jianmei

    2016-01-01

    Highlights: • The hydrothermal stability of Cu-ZSM-5 catalyst was enhanced after surface modification. • An inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer. • The contact between Si and Cu and Al atoms could form Si-O-Al and Si- O−Cu bonds. • The redox and acidity properties of Cu-ZSM-5-CLD-Aged catalyst were largely retained. • The adsorption and activation of NO and NH_3 was almost unchanged over Cu-ZSM-5-CLD catalyst before and after hydrothermal treatment. - Abstract: The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH_3. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu"2"+ from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

  2. Preliminary X-ray crystallographic studies of BthTX-II, a myotoxic Asp49-phospholipase A2 with low catalytic activity from Bothrops jararacussu venom

    International Nuclear Information System (INIS)

    Corrêa, L. C.; Marchi-Salvador, D. P.; Cintra, A. C. O.; Soares, A. M.; Fontes, M. R. M.

    2006-01-01

    A myotoxic Asp49-PLA 2 with low catalytic activity from B. jararacussu (BthTX-II) was crystallized in the monoclinic crystal system; a complete X-ray diffraction data set was collected and a molecular-replacement solution was obtained. The oligomeric structure of BthTX-II resembles those of the Asp49-PLA 2 PrTX-III and all bothropic Lys49-PLA 2 s. For the first time, a complete X-ray diffraction data set has been collected from a myotoxic Asp49-phospholipase A 2 (Asp49-PLA 2 ) with low catalytic activity (BthTX-II from Bothrops jararacussu venom) and a molecular-replacement solution has been obtained with a dimer in the asymmetric unit. The quaternary structure of BthTX-II resembles the myotoxin Asp49-PLA 2 PrTX-III (piratoxin III from B. pirajai venom) and all non-catalytic and myotoxic dimeric Lys49-PLA 2 s. In contrast, the oligomeric structure of BthTX-II is different from the highly catalytic and non-myotoxic BthA-I (acidic PLA 2 from B. jararacussu). Thus, comparison between these structures should add insight into the catalytic and myotoxic activities of bothropic PLA 2 s

  3. Selectively catalytic activity of metal–organic frameworks depending on the N-position within the pyridine ring of their building blocks

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Haitao, E-mail: xuhaitao@ecust.edu.cn [School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 (China); Gou, Yongxia; Ye, Jing; Xu, Zhen-liang [School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 (China); Wang, Zixuan [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-05-15

    Iron metal–organic frameworks (MOFs) [Fe(L){sub 2}(SCN){sub 2}]{sub ∝} (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H{sub 2}O solvent system. 1Fe exhibits a two-dimensional extended-grid network, whereas 2Fe exhibits a stair-like double-chain; the N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Furthermore, selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF; micro/nanoparticles of the layered MOF were therefore investigated for new potential applications of micro/nano MOFs. - Graphical abstract: Iron metal–organic frameworks (MOFs) [Fe(L){sub 2}(SCN){sub 2}]{sub ∝} (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H{sub 2}O solvent system. The N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF. - Highlights: • Synthesis and structure of metal–organic framework [Fe(L){sub 2}(SCN){sub 2}]{sub ∝}. • Selectively catalytic activity depending on the N-position within the pyridine ring. • The degradation and conversion of methyl orange.

  4. Selectively catalytic activity of metal–organic frameworks depending on the N-position within the pyridine ring of their building blocks

    International Nuclear Information System (INIS)

    Xu, Haitao; Gou, Yongxia; Ye, Jing; Xu, Zhen-liang; Wang, Zixuan

    2016-01-01

    Iron metal–organic frameworks (MOFs) [Fe(L) 2 (SCN) 2 ] ∝ (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H 2 O solvent system. 1Fe exhibits a two-dimensional extended-grid network, whereas 2Fe exhibits a stair-like double-chain; the N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Furthermore, selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF; micro/nanoparticles of the layered MOF were therefore investigated for new potential applications of micro/nano MOFs. - Graphical abstract: Iron metal–organic frameworks (MOFs) [Fe(L) 2 (SCN) 2 ] ∝ (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H 2 O solvent system. The N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF. - Highlights: • Synthesis and structure of metal–organic framework [Fe(L) 2 (SCN) 2 ] ∝ . • Selectively catalytic activity depending on the N-position within the pyridine ring. • The degradation and conversion of methyl orange.

  5. Zn-Mo/HZSM-5 Catalyst for Gasoil Range Hydrocarbon Production by Catalytic Hydrocracking of Ceiba pentandra oil

    Directory of Open Access Journals (Sweden)

    Yustia Wulandari Mirzayanti

    2018-01-01

    Full Text Available Biofuel from vegetable oil becomes one of the most suitable and logical alternatives to replace fossil fuel. The research focused on various metal ratio Zinc/Molybdenum/HZSM-5 (Zn-Mo/HZSM-5 catalyst to produce liquid hydrocarbon via catalytic hydrocracking of Ceiba penandra oil. The catalytic hydrocracking process has been applied in this study to crack Ceiba pentandra oil into a gasoil range hydrocarbon using Zn-Mo/HZSM-5 as a catalyst. The effect of various reaction temperature on the catalytic hydrocracking of Ceiba pentandra oil were studied. The Zn-Mo/HZSM-5 catalyst with metal ratio was prepared by incipient wetness impregnation method. This process used slurry pressure batch reactor with a mechanical stirrer. A series of experiments were carried out in the temperature range from 300-400 oC for 2 h at pressure between 10-15 bar. The conversion and selectivity were estimated. The liquid hydrocarbon product were identified to gasoline, kerosene, and gas oil. The results show that the use of Zn-Mo/HZSM-5 can produce gas oil as the most component in the product. Overall, the highest conversion and selectivity of gas oil range hydrocarbon was obtained when the ZnMo/HZSM-5 metal ratio was Zn(2.86 wt.%-Mo(5.32 wt.%/HZSM-5 and the name is Zn-Mo/HZSM-5_102. The highest conversion was obtained at 63.31 % and n-paraffin (gas oil range selectivity was obtained at 90.75 % at a temperature of 400 oC. Ceiba pentandra oil can be recommended as the source of inedible vegetable oil to produce gasoil as an environmentally friendly transportation fuel. Copyright © 2018 BCREC Group. All rights reserved Received: 8th September 2017; Revised: 9th September 2017; Accepted: 17th September 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Mirzayanti, Y.W., Kurniawansyah, F., Prajitno, D.H., Roesyadi, A. (2018. Zn-Mo/HZSM-5 Catalyst for Gasoil Range Hydrocarbon Production by Catalytic Hydrocracking of Ceiba pentandra

  6. Extremely low temperature properties of epoxy GFRP

    International Nuclear Information System (INIS)

    Kadotani, Kenzo; Nagai, Matao; Aki, Fumitake.

    1983-01-01

    The examination of fiber-reinforced plastics, that is, plastics such as epoxy, polyester and polyimide reinforced with high strength fibers such as glass, carbon, boron and steel, for extremely low temperature use began from the fuel tanks of rockets. Therafter, the trial manufacture of superconducting generators and extremely low temperature transformers and the manufacture of superconducting magnets for nuclear fusion experimental setups became active, and high performance FRPs have been adopted, of which the extremely low temperature properties have been sufficiently grasped. Recently, the cryostats made of FRPs have been developed, fully utilizing such features of FRPs as high strength, high rigidity, non-magnetic material, insulation, low heat conductivity, light weight and the freedom of molding. In this paper, the mechanical properties at extremely low temperature of the plastic composite materials used as insulators and structural materials for extremely low temperature superconducting equipment is outlined, and in particular, glass fiber-reinforced epoxy laminates are described somewhat in detail. The fracture strain of GFRP at extremely low temperature is about 1.3 times as large as that at room temperature, but at extremely low temperature, clear cracking occurred at 40% of the fracture strain. The linear thermal contraction of GFRP showed remarkable anisotropy. (Kako, I.)

  7. Low temperature nitrogen chemistry. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Glarborg, P.; Dam-Johansen, K.; Kristensen, P.G.; Alzueta, M.; Roejel, H.

    1997-04-01

    The results of a two tasks program on Natural Gas Reburning are reported. The work involved an experimental and theoretical study of the reburning and hybrid reburning/SNCR chemistry in the 1000-1500 K range. The interactions between hydrocarbon and nitrogen chemistry under fuel-rich conditions were investigated in order to assess the NO{sub x} reduction potential of low temperature reburning. The effect of reburn fuel(carbon monoxide, methane, acetylene, ethylene, ethane, and methane/ethane mixture), temperature, stoichiometry, reactant dilution, reaction time, and inlet NO level were studied. The results indicate a significant NO reduction potential even below 1400 K, but extrapolation to practical conditions are complicated by inadequate knowledge of the detailed chemistry as well as of the effect of mixing. The possibilities of enhancing the conversion to N{sub 2} instead of NO by adding selective reducing agents (hybrid reburning/SNCR) were evaluated. Our results indicate little synergistic effect between reburn and SNCR. The most simple configuration, where the selective reducing agent is injected together with the burnout air, is not expected to be effective, unless the N-agent is injected in form of an aqueous solution. A chemical kinetic model for reburning and reburn/SNCR is listed and can be obtained by e-mail from pgl(commerical at)kt.dtu.dk.(au) 145 refs.

  8. Improvement of performance in low temperature solid oxide fuel cells operated on ethanol and air mixtures using Cu-ZnO-Al2O3 catalyst layer

    Science.gov (United States)

    Morales, M.; Espiell, F.; Segarra, M.

    2015-10-01

    Anode-supported single-chamber solid oxide fuel cells with and without Cu-ZnO-Al2O3 catalyst layers deposited on the anode support have been operated on ethanol and air mixtures. The cells consist of gadolinia-doped ceria electrolyte, Ni-doped ceria anode, and La0.6Sr0.4CoO3-δ-doped ceria cathode. Catalyst layers with different Cu-ZnO-Al2O3 ratios are deposited and sintered at several temperatures. Since the performance of single-chamber fuel cells strongly depends on catalytic properties of electrodes for partial oxidation of ethanol, the cells are electrochemically characterized as a function of the temperature, ethanol-air molar ratio and gas flow rate. In addition, catalytic activities of supported anode, catalytic layer-supported anode and cathode for partial oxidation of ethanol are analysed. Afterwards, the effect of composition and sintering temperature of catalyst layer on the cell performance are determined. The results indicate that the cell performance can be significantly enhanced using catalyst layers of 30:35:35 and 40:30:30 wt.% Cu-ZnO-Al2O3 sintered at 1100 °C, achieving power densities above 50 mW cm-2 under 0.45 ethanol-air ratio at temperatures as low as 450 °C. After testing for 15 h, all cells present a gradual loss of power density, without carbon deposition, which is mainly attributed to the partial re-oxidation of Ni at the anode.

  9. Low-temperature thermal expansion

    International Nuclear Information System (INIS)

    Collings, E.W.

    1986-01-01

    This chapter discusses the thermal expansion of insulators and metals. Harmonicity and anharmonicity in thermal expansion are examined. The electronic, magnetic, an other contributions to low temperature thermal expansion are analyzed. The thermodynamics of the Debye isotropic continuum, the lattice-dynamical approach, and the thermal expansion of metals are discussed. Relative linear expansion at low temperatures is reviewed and further calculations of the electronic thermal expansion coefficient are given. Thermal expansions are given for Cu, Al and Ti. Phenomenologic thermodynamic relationships are also discussed

  10. GENERIC VERIFICATION PROTOCOL FOR DETERMINATION OF EMISSIONS REDUCTIONS FROM SELECTIVE CATALYTIC REDUCTIONS CONTROL TECHNOLOGIES FOR HIGHWAY, NONROAD, AND STATIONARY USE DIESEL ENGINES

    Science.gov (United States)

    The protocol describes the Environmental Technology Verification (ETV) Program's considerations and requirements for verification of emissions reduction provided by selective catalytic reduction (SCR) technologies. The basis of the ETV will be comparison of the emissions and perf...

  11. Application of low temperature plasmas for restoration/conservation of archaeological objects

    Science.gov (United States)

    Krčma, F.; Blahová, L.; Fojtíková, P.; Graham, W. G.; Grossmannová, H.; Hlochová, L.; Horák, J.; Janová, D.; Kelsey, C. P.; Kozáková, Z.; Mazánková, V.; Procházka, M.; Přikryl, R.; Řádková, L.; Sázavská, V.; Vašíček, M.; Veverková, R.; Zmrzlý, M.

    2014-12-01

    The low-temperature low-pressure hydrogen based plasmas were used to study the influence of processes and discharge conditions on corrosion removal. The capacitive coupled RF discharge in the continuous or pulsed regime was used at operating pressure of 100-200 Pa. Plasma treatment was monitored by optical emission spectroscopy. To be able to study influence of various process parameters, the model corroded samples with and without sandy incrustation were prepared. The SEM-EDX analyzes were carried out to verify corrosion removal efficiency. Experimental conditions were optimized for the selected most frequent materials of original metallic archaeological objects (iron, bronze, copper, and brass). Chlorides removal is based on hydrogen ion reactions while oxides are removed mainly by neutral species interactions. A special focus was kept for the samples temperature because it was necessary to avoid any metallographic changes in the material structure. The application of higher power pulsed regime with low duty cycle seems be the best treatment regime. The low pressure hydrogen plasma is not applicable for objects with a very broken structure or for nonmetallic objects due to the non-uniform heat stress. Due to this fact, the new developed plasmas generated in liquids were applied on selected original archaeological glass materials.

  12. Low-Temperature Supercapacitors

    Science.gov (United States)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.

    2008-01-01

    An effort to extend the low-temperature operational limit of supercapacitors is currently underway. At present, commercially available non-aqueous supercapacitors are rated for a minimum operating temperature of -40 C. A capability to operate at lower temperatures would be desirable for delivering power to systems that must operate in outer space or in the Polar Regions on Earth. Supercapacitors (also known as double-layer or electrochemical capacitors) offer a high power density (>1,000 W/kg) and moderate energy density (about 5 to 10 Wh/kg) technology for storing energy and delivering power. This combination of properties enables delivery of large currents for pulsed applications, or alternatively, smaller currents for low duty cycle applications. The mechanism of storage of electric charge in a supercapacitor -- at the electrical double-layer formed at a solid-electrode/liquid-electrolyte interface -- differs from that of a primary or secondary electrochemical cell (i.e., a battery) in such a manner as to impart a long cycle life (typically >10(exp 6) charge/discharge cycles).

  13. Optimization criteria for low temperature waste heat utilization

    International Nuclear Information System (INIS)

    Kranebitter, F.

    1977-01-01

    A special case in this field is the utilization of very low temperature waste heat. The temperature level under consideration in this paper is in the range between the body temperature of human beings and their environment. The waste heat from power generation and industrial processes is also considered. Thermal energy conversion will be mainly accomplished by heat cycles where discharged waste heat is reverse proportional to the upper cycle temperature. Limiting this upper cycle temperature by technological reasons the optimization of the heat cycle will depend on the nature of the cycle itself and specially on the temperature selected for the heat discharge. The waste heat discharge is typical for the different kinds of heat cycles and the paper presents the four most important of them. Feasible heat transfer methods and their economic evaluations are discussed and the distillation processes will be the basis for further considerations. The waste heat utilization for distillation purposes could be realized by three different cycles, the open cycle, the closed cycle and the multy cycle. Resulting problems as deaeration of large water streams and removal of the dissolved gases and their solutions are also discussed. (M.S.)

  14. Catalytic recruitment in the inactivation of acetylcholinesterase by soman: temperature dependence of the solvent isotope effect

    International Nuclear Information System (INIS)

    Kovach, I.M.; Huber, J.H.A.; Schowen, R.L.

    1988-01-01

    3,3-Dimethyl-2-butyl methylphosphonofluoridate (soman) recruits at least 60-70% of the catalytic power of acetylcholinesterase during phosphonylation of the active-site serine, as compared with the acetylation by acetylcholine. The solvent isotope effect is 1.34 +/- 0.11 and is temperature independent within experimental error between 5 and 45 0 C. This observation is quite similar to what has been found for the reactions of aryl acetates and anilides. Average activation parameters for the same temperature range are ΔH* = 7.3 +/- 0.6 kcal/mol and ΔS* = -4 +/- 2 eu (H 2 O) and ΔH* = 7.1 +/- 0.4 kcal/mol and ΔS* = -6 +/- 1 eu (D 2 O). A rate-limiting process with 50% contribution of an induced-fit conformational change is supported by the data

  15. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang Wang; Zhijun Zhou; Weijuan Yang; Junhu Zhou; Jianzhong Liu; Zhihua Wang; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China)

    2010-06-15

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H{sub 2}PtCl{sub 6}. The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture. (author)

  16. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yang; Zhou Zhijun [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China); Yang Weijuan, E-mail: 10508107@zju.edu.c [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhou Junhu; Liu Jianzhong; Wang Zhihua; Cen Kefa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China)

    2010-06-15

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H{sub 2}PtCl{sub 6}. The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture.

  17. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    International Nuclear Information System (INIS)

    Wang Yang; Zhou Zhijun; Yang Weijuan; Zhou Junhu; Liu Jianzhong; Wang Zhihua; Cen Kefa

    2010-01-01

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H 2 PtCl 6 . The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture.

  18. Hydrogen Production From catalytic reforming of greenhouse gases ...

    African Journals Online (AJOL)

    ADOWIE PERE

    a fixed bed stainless steel reactor. The 20wt%. ... catalytic activity for hydrogen production with the highest yield and selectivity of 32.5% and 17.6% respectively. © JASEM ... CO2 reforming of methane is however not fully developed ..... Design and preparation of .... catalytic nickel membrane for gas to liquid (GTL) process.

  19. Hydrogenation of Maltose in Catalytic Membrane Reactor for Maltitol Production

    Directory of Open Access Journals (Sweden)

    Makertihartha I.G.B.N.

    2018-01-01

    Full Text Available Maltitol is one of the low-calorie sweeteners which has a major role in food industries. Due to its characteristics of comparable sweetness level to sucrose, maltitol can be a suitable sugar replacement. In this work, catalytic membrane reactor (CMR was examined in maltitol production through hydrogenation of maltose. Commercial ceramic membrane impregnated with Kalcat 8030 Nickel was used as the CMR. The reaction was conducted at a batch mode operation, 95 to 110°C of temperature, and 5 to 8 bar of pressure. In the range of working conditions used in this study, up to 47% conversion was achieved. The reaction conversion was significantly affected by temperature and pressure. Results of this preliminary study indicated that CMR can be used for hydrogenation of maltose with good performance under a relatively low operating pressure.

  20. WORKSHOP: Low temperature devices

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    With extraterrestrial neutrinos (whether from the sun or further afield) continuing to make science news, and with the search for the so far invisible 'dark matter' of the universe a continual preoccupation, physicists from different walks of life (solid state, low temperature, particles, astrophysics) gathered at a workshop on low temperature devices for the detection of neutrinos and dark matter, held from 12-13 March at Ringberg Castle on Lake Tegernsee in the Bavarian Alps, and organized by the Max Planck Institute for Physics and Astrophysics in Munich

  1. WORKSHOP: Low temperature devices

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-06-15

    With extraterrestrial neutrinos (whether from the sun or further afield) continuing to make science news, and with the search for the so far invisible 'dark matter' of the universe a continual preoccupation, physicists from different walks of life (solid state, low temperature, particles, astrophysics) gathered at a workshop on low temperature devices for the detection of neutrinos and dark matter, held from 12-13 March at Ringberg Castle on Lake Tegernsee in the Bavarian Alps, and organized by the Max Planck Institute for Physics and Astrophysics in Munich.

  2. Catalytic modification of cellulose and hemicellulose - Sugarefine

    Energy Technology Data Exchange (ETDEWEB)

    Repo, T. [Helsinki Univ. (Finland),Laboratory of Inorganic Chemistry], email: timo.repo@helsinki.fi

    2012-07-01

    The main goal of the project is to develop catalytic methods for the modification of lignocellulose-based saccharides in the biorefineries. The products of these reactions could be used for example as biofuel components, raw materials for the chemical industry, solvents and precursors for biopolymers. The catalyst development aims at creating efficient, selective and green catalytic methods for profitable use in biorefineries. The project is divided in three work packages: In WP1 (Catalytic dehydration of cellulose) the aim is at developing non-toxic, efficient methods for the catalytic dehydration of cellulose the target molecule being here 5-hydroxymethylfurfural (5-HMF). 5-HMF is an interesting platform chemical for the production of fuel additives, solvents and polymers. In WP2 (Catalytic reduction), the objective of the catalytic reduction studies is to produce commercially interesting monofunctional chemicals, such as 1-butanol or 2-methyltetrahydrofuran (2-MeTHF). In WP3 (Catalytic oxidation), the research focuses on developing a green and efficient oxidation method for producing acids. Whereas acetic and formic acids are bulk chemicals, diacids such as glucaric and xylaric acids are valuable specialty chemicals for detergent, polymer and food production.

  3. Promotion of redox and stability features of doped Ce–W–Ti for NH{sub 3}-SCR reaction over a wide temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Kun [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Han, Weiliang; Lu, Gongxuan [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lu, Jiangyin, E-mail: jiangyinlu6410@163.com [Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Tang, Zhicheng, E-mail: tangzhicheng@licp.cas.cn [State Key Laboratory for Oxo Synthesis and Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhen, Xinping [Key laboratory of Oil & Gas Fine Chemical, Ministry of Education, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China)

    2016-08-30

    Graphical abstract: In this study, different transition metals were introduced into Ce–W–Ti catalyst in order to promote the low temperature activity. The Cu/Ce–W–Ti catalyst prepared via a co-precipitation method displayed more excellent performance in the wide temperature range (260–400 °C). - Highlights: • Redox ability of Ce–W–Ti was enhanced by introduction of CuO. • The optimum catalyst provided high activity and broad operation window. • Cu/Ce–W–Ti presents an adequate tolerance to SO{sub 2} and hydrothermal aging. - Abstract: In this study, transition metals Co, Mn, and Cu were introduced into a Ce–W–Ti catalyst to promote low-temperature catalytic activity. Among these metal-modified M/Ce–W–Ti catalysts (M represents Co, Mn, or Cu), the Cu/Ce–W–Ti catalyst with an optimized Cu content of 5 wt.% exhibited more than 90% conversion of nitrogen oxide (NO{sub x}) in the selective catalytic reduction by NH{sub 3} over a wide temperature range (260–400 °C). This catalyst likewise exhibited higher resistance to SO{sub 2} gas and water vapor under severe test conditions. On the basis of the characterization results by powder X-ray diffraction and X-ray photoelectron spectroscopy, we concluded that the superior catalytic properties of the Cu/Ce–W–Ti catalyst could be attributed to the highly dispersed Cu species, which increased the contents of Ce{sup 3+} species and adsorbed oxygen species in the catalysts. In addition, the NH{sub 3} temperature-programmed desorption results demonstrated that the Cu species doped into the Ce–W–Ti catalysts optimized surface acid content.

  4. Selection of working fluids for a novel low-temperature geothermally-powered ORC based cogeneration system

    International Nuclear Information System (INIS)

    Guo, T.; Wang, H.X.; Zhang, S.J.

    2011-01-01

    Highlights: → Performances of a novel cogeneration system using low-temperature geothermal sources under disturbance conditions were investigated. → It aimed at identifying appropriate fluids yielding high PPR and QQR values. → Fluids group presenting higher normal boiling point values showed averagely 7.7% higher PPR with a larger variation than QQR values under disturbance conditions. → Smaller T P value, higher η t value, higher geothermal source parameters and lower heating supply parameters led to higher PPR values but lower QQR values. -- Abstract: A novel cogeneration system driven by low-temperature geothermal sources was investigated in this study. This system consists of a low-temperature geothermally-powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The main purpose is to identify appropriate fluids which may yield high PPR (the ratio of power produced by the power generation subsystem to power consumed by the heat pump subsystem) value and QQR (the ratio of heat supplied to the user to heat produced by the geothermal source) value. Performances of the novel cogeneration system under disturbance conditions have also been studied. Results indicate that fluids group presenting higher normal boiling point values shows averagely 7.7% higher PPR values and R236ea and R245ca outstand among the group. ΔT P (pinch temperature difference in heat exchangers) and η t (turbine efficiency) values play more important roles on the variation of PPR values. QQR values change slightly with various ΔT P , η t and η rp (refrigerant pump efficiency) values while the variation range is larger under various geothermal source and heating supply parameters. Smaller ΔT P value, higher η t value, higher geothermal source parameters and lower heating supply parameters lead to higher PPR values but lower QQR values.

  5. Diethyl Ether Production during Catalytic Dehydration of Ethanol over Ru- and Pt- modified H-beta Zeolite Catalysts.

    Science.gov (United States)

    Kamsuwan, Tanutporn; Praserthdam, Piyasan; Jongsomjit, Bunjerd

    2017-01-01

    In the present study, the catalytic dehydration of ethanol over H-beta zeolite (HBZ) catalyst with ruthenium (Ru-HBZ) and platinum (Pt-HBZ) modification was investigated. Upon the reaction temperature between 200 and 400°C, it revealed that ethanol conversion and ethylene selectivity increased with increasing temperature for both Ru and Pt modification. At lower temperature (200 to 250°C), diethyl ether (DEE) was the major product. It was found that Ru and Pt modification on HBZ catalyst can result in increased DEE yield at low reaction temperature due to increased ethanol conversion without a significant change in DEE selectivity. By comparing the DEE yield of all catalysts in this study, the Ru-HBZ catalyst apparently exhibited the highest DEE yield (ca. 47%) at 250°C. However, at temperature from 350 to 400°C, the effect of Ru and Pt was less pronounced on ethylene yield. With various characterization techniques, the effects of Ru and Pt modification on HBZ catalyst were elucidated. It revealed that Ru and Pt were present in the highly dispersed forms and well distributed in the catalyst granules. It appeared that the weak acid sites measured by NH 3 temperature-programmed desorption technique also decreased with Ru and Pt promotion. Thus, the increased DEE yields with the Ru and Pt modification can be attributed to the presence of optimal weak acid sites leading to increased intrinsic activity of the catalysts. It can be concluded that the modification of Ru and Pt on HBZ catalyst can improve the DEE yields by ca. 10%.

  6. Basics of Low-temperature Refrigeration

    CERN Document Server

    Alekseev, A.

    2014-07-17

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  7. Basics of Low-temperature Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A [Linde AG, Munich (Germany)

    2014-07-01

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  8. Low-temperature growth and photoluminescence property of ZnS nanoribbons.

    Science.gov (United States)

    Zhang, Zengxing; Wang, Jianxiong; Yuan, Huajun; Gao, Yan; Liu, Dongfang; Song, Li; Xiang, Yanjuan; Zhao, Xiaowei; Liu, Lifeng; Luo, Shudong; Dou, Xinyuan; Mou, Shicheng; Zhou, Weiya; Xie, Sishen

    2005-10-06

    At a low temperature of 450 degrees C, ZnS nanoribbons have been synthesized on Si and KCl substrates by a simple chemical vapor deposition (CVD) method with a two-temperature-zone furnace. Zinc and sulfur powders are used as sources in the different temperature zones. X-ray diffraction (XRD), selected area electron diffraction (SEAD), and transmission electron microscopy (TEM) analysis show that the ZnS nanoribbons are the wurtzite structure, and there are two types-single-crystal and bicrystal nanoribbons. Photoluminescence (PL) spectrum shows that the spectrum mainly includes two parts: a purple emission band centering at about 390 nm and a blue emission band centering at about 445 nm with a weak green shoulder around 510 nm.

  9. Nb effect in the nickel oxide-catalyzed low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2012-01-01

    A method for the preparation of NiO and Nb-NiO nanocomposites is developed, based on the slow oxidation of a nickel-rich Nb-Ni gel obtained in citric acid. The resulting materials have higher surface areas than those obtained by the classical evaporation method from nickel nitrate and ammonium niobium oxalate. These consist in NiO nanocrystallites (7-13 nm) associated, at Nb contents >3 at.%., with an amorphous thin layer (1-2 nm) of a niobium-rich mixed oxide with a structure similar to that of NiNb 2O 6. Unlike bulk nickel oxides, the activity of these nanooxides for low-temperature ethane oxidative dehydrogenation (ODH) has been related to their redox properties. In addition to limiting the size of NiO crystallites, the presence of the Nb-rich phase also inhibits NiO reducibility. At Nb content >5 at.%, Nb-NiO composites are thus less active for ethane ODH but more selective, indicating that the Nb-rich phase probably covers part of the unselective, non-stoichiometric, active oxygen species of NiO. This geometric effect is supported by high-resolution transmission electron microscopy observations. The close interaction between NiO and the thin Nb-rich mixed oxide layer, combined with possible restructuration of the nanocomposite under ODH conditions, leads to significant catalyst deactivation at high Nb loadings. Hence, the most efficient ODH catalysts obtained by this method are those containing 3-4 at.% Nb, which combine high activity, selectivity, and stability. The impact of the preparation method on the structural and catalytic properties of Nb-NiO nanocomposites suggests that further improvement in NiO-catalyzed ethane ODH can be expected upon optimization of the catalyst. © 2011 Elsevier Inc. All rights reserved.

  10. Catalytic reduction of NH4NO3 by NO. Effects of solid acids and implications for low temperature DeNOx processes

    International Nuclear Information System (INIS)

    Savara, Aditya; Li, Mei-Jun; Sachtler, Wolfgang M.H.; Weitz, Eric

    2008-01-01

    Ammonium nitrate is thermally stable below 250 C and could potentially deactivate low temperature NO x reduction catalysts by blocking active sites. It is shown that NO reduces neat NH 4 NO 3 above its 170 C melting point, while acidic solids catalyze this reaction even at temperatures below 100 C. NO 2 , a product of the reduction, can dimerize and then dissociate in molten NH 4 NO 3 to NO + + NO 3 - , and may be stabilized within the melt as either an adduct or as HNO 2 formed from the hydrolysis of NO + or N 2 O 4 . The other product of reduction, NH 4 NO 2 , readily decomposes at ≤100 C to N 2 and H 2 O, the desired end products of DeNO x catalysis. A mechanism for the acid catalyzed reduction of NH 4 NO 3 by NO is proposed, with HNO 3 as an intermediate. These findings indicate that the use of acidic catalysts or promoters in DeNO x systems could help mitigate catalyst deactivation at low operating temperatures (<150 C). (author)

  11. Selective Catalytic Hydrogenation of Arenols by a Well-Defined Complex of Ruthenium and Phosphorus–Nitrogen PN3–Pincer Ligand Containing a Phenanthroline Backbone

    KAUST Repository

    Li, Huaifeng; Wang, Yuan; Lai, Zhiping; Huang, Kuo-Wei

    2017-01-01

    Selective catalytic hydrogenation of aromatic compounds is extremely challenging using transition-metal catalysts. Hydrogenation of arenols to substituted tetrahydronaphthols or cyclohexanols has been reported only with heterogeneous catalysts. Herein, we demonstrate the selective hydrogenation of arenols to the corresponding tetrahydronaphthols or cyclohexanols catalyzed by a phenanthroline-based PN3-ruthenium pincer catalyst.

  12. Selective Catalytic Hydrogenation of Arenols by a Well-Defined Complex of Ruthenium and Phosphorus–Nitrogen PN3–Pincer Ligand Containing a Phenanthroline Backbone

    KAUST Repository

    Li, Huaifeng

    2017-05-30

    Selective catalytic hydrogenation of aromatic compounds is extremely challenging using transition-metal catalysts. Hydrogenation of arenols to substituted tetrahydronaphthols or cyclohexanols has been reported only with heterogeneous catalysts. Herein, we demonstrate the selective hydrogenation of arenols to the corresponding tetrahydronaphthols or cyclohexanols catalyzed by a phenanthroline-based PN3-ruthenium pincer catalyst.

  13. Improved Low Temperature Performance of Supercapacitors

    Science.gov (United States)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.; Gnanaraj, Joe

    2013-01-01

    Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

  14. Low-temperature carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Strankmuller, J

    1954-01-01

    The low-temperature carbonization plant at Boehlen in Eastern Germany (the first in which Lurgi type ovens were installed) worked with a throughput of 300 tons of brown-coal briquets per day per oven since 1936, later increased to 365 tons per day. The rising demand for low-temperature tar for hydrogenation purposes led to development of a modified oven of 450 tons throughput. This was achieved by stepping up the flow of the circulating gas and air mixture from 420,000 to 560,000 cubic feet per hour and by additional rows of V-shaped deflectors across the width of the oven chamber, which break up and loosen the charge, thus reducing cooling-gas pressure and allowing a greater flow of scavenging gas. The distance traversed by each briquet is nearly doubled, and the temperature gradient is less. It is claimed that the tar and the coke from modified ovens are of comparable quality. The compressive strength of the briquets was found to have an appreciable effect on the output. Better qts the chemistry, mechanism and thermodynamics of the Fischer-Tropsch reaction and aectromagnetic radiation.

  15. Green technology for conversion of renewable hydrocarbon based on plasma-catalytic approach

    Science.gov (United States)

    Fedirchyk, Igor; Nedybaliuk, Oleg; Chernyak, Valeriy; Demchina, Valentina

    2016-09-01

    The ability to convert renewable biomass into fuels and chemicals is one of the most important steps on our path to green technology and sustainable development. However, the complex composition of biomass poses a major problem for established conversion technologies. The high temperature of thermochemical biomass conversion often leads to the appearance of undesirable byproducts and waste. The catalytic conversion has reduced yield and feedstock range. Plasma-catalytic reforming technology opens a new path for biomass conversion by replacing feedstock-specific catalysts with free radicals generated in the plasma. We studied the plasma-catalytic conversion of several renewable hydrocarbons using the air plasma created by rotating gliding discharge. We found that plasma-catalytic hydrocarbon conversion can be conducted at significantly lower temperatures (500 K) than during the thermochemical ( 1000 K) and catalytic (800 K) conversion. By using gas chromatography, we determined conversion products and found that conversion efficiency of plasma-catalytic conversion reaches over 85%. We used obtained data to determine the energy yield of hydrogen in case of plasma-catalytic reforming of ethanol and compared it with other plasma-based hydrogen-generating systems.

  16. High Selectivity of Alkanes Production by Calcium Basic Soap Thermal Decarboxylation

    Directory of Open Access Journals (Sweden)

    Neonufa Godlief F.

    2018-01-01

    Full Text Available Renewable fuel production from vegetable oil and fat or its fatty acids by direct decarboxylation has been widely reported. An innovative approach to produce drop-in fuel via thermal catalytic decarboxylation of basic soap derived from palm stearin reported in this research. The catalytic effect of the calcium and magnesium metals in the basic soap and its decarboxylation on drop-in fuel yield and product distribution was studied. The catalytic effect was tested in the temperature range up to 370°C and atmospheric pressure for 5 hours in a batch reactor. It has been proved that the calcium basic soap decarboxylation, effectively produce the drop-in fuel in carbon ranges C8 – C20, in which more than 78% selectivity toward alkane. Whereas, only 70% selectivity toward alkane has been resulted from the magnesium basic soap decarboxylation.

  17. Thermal activation of catalytic microjets in blood samples using microfluidic chips.

    Science.gov (United States)

    Soler, Lluís; Martínez-Cisneros, Cynthia; Swiersy, Anka; Sánchez, Samuel; Schmidt, Oliver G

    2013-11-21

    We demonstrate that catalytic microjet engines can out-swim high complex media composed of red blood cells and serum. Despite the challenge presented by the high viscosity of the solution at room temperature, the catalytic microjets can be activated at physiological temperature and, consequently, self-propel in diluted solutions of blood samples. We prove that these microjets self-propel in 10× diluted blood samples using microfluidic chips.

  18. Thermal activation of catalytic microjets in blood samples using microfluidic chips†

    Science.gov (United States)

    Soler, Lluís; Martínez-Cisneros, Cynthia; Swiersy, Anka; Sánchez, Samuel; Schmidt, Oliver G.

    2014-01-01

    We demonstrate that catalytic microjet engines can out-swim high complex media composed of red blood cells and serum. Despite the challenge presented by the high viscosity of the solution at room temperature, the catalytic microjets can be activated at physiological temperature and, consequently, self-propel in diluted solutions of blood samples. We prove that these microjets self-propel in 10× diluted blood samples using microfluidic chips. PMID:24089195

  19. Thermal conductivity at very low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Locatelli, M [CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Service des Basses Temperatures

    1976-06-01

    The interest of low and very low temperatures in solid physics and especially that of thermal measurements is briefly mentioned. Some notes on the thermal conductivity of dielectrics, the method and apparatus used to measure this property at very low temperatures (T<1.5K) and some recent results of fundamental and applied research are then presented.

  20. Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tao; Shi, Juan; Liu, Jian, E-mail: liujian@cup.edu.cn; Wang, Daxi; Zhao, Zhen, E-mail: zhenzhao@cup.edu.cn; Cheng, Kai; Li, Jianmei

    2016-07-01

    Highlights: • The hydrothermal stability of Cu-ZSM-5 catalyst was enhanced after surface modification. • An inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer. • The contact between Si and Cu and Al atoms could form Si-O-Al and Si- O−Cu bonds. • The redox and acidity properties of Cu-ZSM-5-CLD-Aged catalyst were largely retained. • The adsorption and activation of NO and NH{sub 3} was almost unchanged over Cu-ZSM-5-CLD catalyst before and after hydrothermal treatment. - Abstract: The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH{sub 3}. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu{sup 2+} from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

  1. Effect of Phosphine Doping and the Surface Metal State of Ni on the Catalytic Performance of Ni/Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Xiaoru Li

    2015-04-01

    Full Text Available Ni-based catalysts as replacement for noble metal catalysts are of particular interest in the catalytic conversion of biomass due to their cheap and satisfactory catalytic activity. The Ni/SiO2 catalyst has been studied for the hydrogenolysis of glycerol, and doping with phosphorus (P found to improve the catalytic performance significantly because of the formation of Ni2P alloys. However, in the present work we disclose a different catalytic phenomenon for the P-doped Ni/Al2O3 catalyst. We found that doping with P has a significant effect on the state of the active Ni species, and thus improves the selectivity to 1,2-propanediol (1,2-PDO significantly in the hydrogenolysis of glycerol, although Ni-P alloys were not observed in our catalytic system. The structure and selectivity correlations were determined from the experimental data, combining the results of X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, hydrogen temperature-programmed reduction (H2-TPR and ammonia temperature-programmed desorption (NH3-TPD. The presence of NiO species, formed from P-doped Ni/Al2O3 catalyst, was shown to benefit the formation of 1,2-PDO. This was supported by the results of the Ni/Al2O3 catalyst containing NiO species with incomplete reduction. Furthermore, the role the NiO species played in the reaction and the potential reaction mechanism over the P-doped Ni/Al2O3 catalyst is discussed. The new findings in the present work open a new vision for Ni catalysis and will benefit researchers in designing Ni-based catalysts.

  2. Weak antilocalization and low-temperature characterization of sputtered polycrystalline bismuth selenide

    Science.gov (United States)

    Sahu, Protyush; Chen, Jun-Yang; Myers, Jason C.; Wang, Jian-Ping

    2018-03-01

    We report a thorough crystal and transport characterization of sputtered polycrystalline BixSe1 -x (20 nm), grown on a thermally oxidized silicon substrate. The crystal and grain structures of the sample are characterized by transmission electron microscopy. Selected-area electron diffraction shows a highly polycrystalline structure. Transport measurements suggest semiconducting behavior of the BixSe1 -x film with a very high carrier concentration (˜1020 cm3) and low mobility [˜8 cm2/(V s)]. High-field magnetoresistance measurements reveal weak antilocalization, to which both the low mobility and the angular dependence suggest an impurity-dominated contribution. Fitting parameters are obtained from 2D magnetoconductivity using the Hikami-Larkin-Nagaoka equation. The variation of the phase coherence length with temperature suggests electron-electron scattering for phase decoherence. Electron-electron interaction theory is used to analyze the low-temperature conductivity.

  3. Automatic low-temperature calorimeter

    International Nuclear Information System (INIS)

    Malyshev, V.M.; Mil'ner, G.A.; Shibakin, V.F.; Sorkin, E.L.

    1986-01-01

    This paper describes a low-temperature adiabatic calorimeter with a range of 1.5-500K. The system for maintaining adiabatic conditions is implemented by two resitance thermometers, whose sensitivity at low temperatures is several orders higher than that of thermocouples. The calorimeter cryostat is installed in an STG-40 portable Dewar flask. The calorimeter is controlled by an Elektronika-60 microcomputer. Standard platinum and germanium thermometers were placed inside of the calorimeter to calibrate the thermometers of the calorimeter and the shield, and the specific heats of specimens of OSCh 11-4 copper and KTP-8 paste were measured to demonstrate the possibilities of the described calorimeter. Experience with the calorimeter has shown that a thorough study of the dependence of heat capacity on temperature (over 100 points for one specimen) can be performed in one or two dats

  4. Temperature selection of goldfish (Carassius auratus L. ) and brook trout (Salvelinus fontinalis Mitch. ) after heterogeneous temperature acclimation

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, R.

    1977-01-01

    Goldfish and brook trout were acclimated heterogeneously to temperature by exposing the head and tail simultaneously to different temperatures. The temperature selection of heterogeneously acclimated fish was tested in a vertical temperature gradient and compared to that of homogeneously acclimated fish. All fish selected temperatures essentially corresponding to the state of acclimation of their head. It is concluded that the brain acts as the main control of temperature selection in fish.

  5. Synthesis of high quality single-walled carbon nanotubes via a catalytic layer reinforced by self-assembled monolayers

    International Nuclear Information System (INIS)

    Adhikari, Prashanta Dhoj; Song, Wooseok; Cha, Myoung-Jun; Park, Chong-Yun

    2013-01-01

    This work reports the synthesis of high quality single-walled carbon nanotubes (SWCNT) using a catalytic layer reinforced by self-assembled monolayers (SAM). Amine-SAM was introduced on a SiO 2 /Si substrate and then an iron nanoparticles solution was dropped on the substrate by spin-coating. This catalytic template was used to grow carbon nanotubes by chemical vapor deposition and the synthesized SWCNT were observed to be prominent, based on the size distribution. Highly dense SWCNT with a diameter of about 1.1-1.2 nm were produced at 800-850 °C. Moreover, the diameter distribution of the SWCNT was more selective at a growth temperature of 900 °C. These findings provide important insights for a SAM support layer that can play the role as a restriction for the agglomeration of iron catalyst and is promising for the synthesis of high quality SWCNT. - Highlights: • Fe nanoparticles on self-assembled monolayers (SAM) containing template is underlined. • Its catalytic behavior to synthesis single-walled carbon nanotubes is studied. • The role of SAM on catalytic template is explored

  6. Low temperature oxidation and spontaneous combustion characteristics of upgraded low rank coal

    Energy Technology Data Exchange (ETDEWEB)

    Choi, H.K.; Kim, S.D.; Yoo, J.H.; Chun, D.H.; Rhim, Y.J.; Lee, S.H. [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2013-07-01

    The low temperature oxidation and spontaneous combustion characteristics of dried coal produced from low rank coal using the upgraded brown coal (UBC) process were investigated. To this end, proximate properties, crossing-point temperature (CPT), and isothermal oxidation characteristics of the coal were analyzed. The isothermal oxidation characteristics were estimated by considering the formation rates of CO and CO{sub 2} at low temperatures. The upgraded low rank coal had higher heating values than the raw coal. It also had less susceptibility to low temperature oxidation and spontaneous combustion. This seemed to result from the coating of the asphalt on the surface of the coal, which suppressed the active functional groups from reacting with oxygen in the air. The increasing upgrading pressure negatively affected the low temperature oxidation and spontaneous combustion.

  7. Minimizing material damage using low temperature irradiation

    International Nuclear Information System (INIS)

    Craven, E.; Hasanain, F.; Winters, M.

    2012-01-01

    Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures. Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials. The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to −80 °C. The effectiveness of microbial kill is also investigated under each of these conditions. The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use. - Highlights: ► A study is performed to quantify low temperature irradiation effects on polymer materials and BIs. ► Low temperature irradiation alters the balance of cross-linking and chain scissoning in polymers. ► Low temperatures provide radioprotection for BIs. ► Benefits of low temperatures are application specific and must be considered when dose setting.

  8. Temperature selection of juvenile Atlantic salmon (Salmo salar) as influenced by various toxic substances

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, R H

    1976-08-01

    Previous exposure to sodium pentachlorophenate (NaPCP), Guthion, malathion, Dursban, and Dibrom lowered the preferred temperature for juvenile Atlantic salmon (Salmo salar) tested in a horizontal temperature gradient. Lindane, CuSO/sub 4/, ZnSO/sub 4/, CdSO/sub 4/, Sevin, heptachlor, and fenitrothion did not change the preferred temperature significantly. Comparison with other published results indicates that those substances that increase the preferred temperature are more toxic (based on relevant changes in 24-h LC50) at low temperatures and vice versa. It is suggested that such shifts in selected temperature may be of potential immediate, short-term, survival value to the fish. (auth)

  9. New Catalytic DNA Biosensors for Radionuclides and Metal ions

    International Nuclear Information System (INIS)

    Lu, Yi

    2003-01-01

    The goals of the project are to develop new catalytic DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides and metal ions, and apply the sensors for on-site, real-time assessment of concentration, speciation and stability of the individual contaminants during and after bioremediation. A negative selection strategy was tested and validated. In vitro selection was shown to yield highly active and specific transition metal ion-dependent catalytic DNA/RNA. A fluorescence resonance energy transfer (FRET) study of in vitro selected DNA demonstrated that the trifluorophore labeled system is a simple and powerful tool in studying complex biomolecules structure and dynamics, and is capable of revealing new sophisticated structural changes. New fluorophore/quenchers in a single fluorosensor yielded improved signal to noise ratio in detection, identification and quantification of metal contaminants. Catalytic DNA fluorescent and colorimetric sensors were shown useful in sensing lead in lake water and in leaded paint. Project results were described in two papers and two patents, and won an international prize

  10. Selective catalytic reduction (SCR) NOx control for small natural gas-fired prime movers

    International Nuclear Information System (INIS)

    Shareef, G.S.; Stone, D.K.; Ferry, K.R.; Johnson, K.L.; Locke, K.S.

    1992-01-01

    The application of selective catalytic reduction (SCR) to small natural gas-fired prime movers at cogeneration facilities and compressor stations could possibly increase due to regulatory forces to limit NO x from such sources. The natural gas industry is presently without a current database with which to evaluate the cost and operating characteristics of SCR under the conditions anticipated for small prime movers. This paper presents the results from a two-phase study undertaken to document SCR applications with emphasis on SCR system performance and costs. The database of small natural gas-fired prime mover SCR experience, focusing on prime mover characterization, SCR system performance, and SCR system costs will be described. Result from analysis of performance and cost data will be discussed, including analytical tools developed to project SCR system performance and costs

  11. Analysis of Low Temperature Organic Rankine Cycles for Solar Applications

    Science.gov (United States)

    Li, Yunfei

    The present work focuses on Organic Rankine Cycle (ORC) systems and their application to low temperature waste heat recovery, combined heat and power as well as off-grid solar power generation applications. As CO_2 issues come to the fore front and fossil fuels become more expensive, interest in low grade heat recovery has grown dramatically in the past few years. Solar energy, as a clean, renewable, pollution-free and sustainable energy has great potential for the use of ORC systems. Several ORC solutions have been proposed to generate electricity from low temperature sources. The ORC systems discussed here can be applied to fields such as solar thermal, biological waste heat, engine exhaust gases, small-scale cogeneration, domestic boilers, etc. The current work presents a thermodynamic and economic analysis for the use of ORC systems to convert solar energy or low exergy energy to generate electrical power. The organic working fluids investigated here were selected to investigate the effect of the fluid saturation temperature on the performance of ORCs. The working fluids under investigation are R113, R245fa, R123, with boiling points between 40°C and 200°C at pressures from 10 kPa to 10 MPa. Ambient temperature air at 20oC to 30oC is utilized as cooling resource, and allowing for a temperature difference 10°C for effective heat transfer. Consequently, the working fluids are condensed at 40°C. A combined first- and second-law analysis is performed by varying some system independent parameters at various reference temperatures. The present work shows that ORC systems can be viable and economical for the applications such as waste heat use and off-grid power generation even though they are likely to be more expensive than grid power.

  12. Catalytic ozonation of ammonia using biomass char and wood fly ash.

    Science.gov (United States)

    Kastner, James R; Miller, Joby; Kolar, Praveen; Das, K C

    2009-05-01

    Catalytic ozonation of gaseous ammonia was investigated at room temperature using wood fly ash (WFA) and biomass char as catalysts. WFA gave the best results, removing ammonia (11 ppmv NH(3), 45% conversion) at 23 degrees C at a residence time of 0.34 s, using 5 g of catalyst or ash at the lowest ozone concentration (62 ppmv). Assuming pseudo zero order kinetics in ozone, a power rate law of -r(NH3) = 7.2 x 10(-8) C(NH3)(0.25) (r, mol g(-1)s(-1), C(NH3)molL(-1)) was determined at 510 ppmv O(3) and 23 degrees C for WFA. Water vapor approximately doubled the oxidation rate using WFA and catalytic ozonation activity was not measured for the char without humidifying the air stream. Overall oxidation rates using the crude catalysts were lower than commercial catalysts, but the catalytic ozonation process operated at significantly lower temperatures (23 vs. 300 degrees C). Nitric oxide was not detected and the percentage of NO(2) formed from NH(3) oxidation ranged from 0.3% to 3% (v/v), with WFA resulting in the lowest NO(2) level (at low O(3) levels). However, we could not verify that N(2)O was not formed, so further research is needed to determine if N(2) is the primary end-product. Additional research is required to develop techniques to enhance the oxidation activity and industrial application of the crude, but potentially inexpensive catalysts.

  13. A study on naphtha catalytic reforming reactor simulation and analysis.

    Science.gov (United States)

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-06-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  14. A study on naphtha catalytic reforming reactor simulation and analysis

    OpenAIRE

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation uni...

  15. Localized temperature stability in Low Temperature Cofired Ceramics (LTCC).

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steven Xunhu; Hsieh, Lung-Hwa.

    2012-04-01

    The base dielectrics of commercial low temperature cofired ceramics (LTCC) systems have a temperature coefficient of resonant frequency ({tau}{sub f}) in the range -50 {approx} -80 ppm/C. In this research we explored a method to realize zero or near zero {tau}{sub f} resonators by incorporating {tau}{sub f} compensating materials locally into a multilayer LTCC structure. To select composition for {tau}{sub f} adjustment, {tau}{sub f} compensating materials with different amount of titanates were formulated, synthesized, and characterized. Chemical interactions and physical compatibility between the {tau}{sub f} modifiers and the host LTCC dielectrics were investigated. Studies on stripline (SL) resonator panels with multiple compensating dielectrics revealed that: 1) compositions using SrTiO{sub 3} provide the largest {tau}{sub f} adjustment among titanates, 2) the {tau}{sub f} compensation is proportional to the amount of SrTiO{sub 3} in compensating materials, as well as the thickness of the compensating layer, and 3) the most effective {tau}{sub f} compensation is achieved when the compensating dielectric is integrated next to the SL. Using the effective dielectric constant of a heterogeneous layered dielectric structure, results from Method of Momentum (MoM) electromagnetic simulations are consistent with the experimental observations.

  16. Use of Low-Temperature Geothermal Energy for Desalination in the Western United States

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, Craig S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Akar, Sertac [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cath, Tzahi [Colorado School of Mines, Golden, CO (United States); Vanneste, Johan [Colorado School of Mines, Golden, CO (United States); Geza, Mengistu [Colorado School of Mines, Golden, CO (United States)

    2015-11-01

    This joint project between the National Renewable Energy Laboratory and the Colorado School of Mines has examined the potential of using low-temperature geothermal resources for desalination. The temperature range in question is not well suited for electricity generation, but can be used for direct heating. Accordingly, the best integration approaches use thermal desalination technologies such as multi-effect distillation (MED) or membrane distillation (MD), rather than electric-driven technologies such as reverse osmosis (RO). The examination of different desalination technologies led to the selection of MD for pairing with geothermal energy. MD operates at near-ambient pressure and temperatures less than 100°C with hydrophobic membranes. The technology is modular like RO, but the equipment costs are lower. The thermal energy demands of MD are higher than MED, but this is offset by an ability to run at lower temperatures and a low capital cost. Consequently, a geothermal-MD system could offer a low capital cost and, if paired with low-cost geothermal energy, a low operating cost. The target product water cost is $1.0 to $1.5 per cubic meter depending on system capacity and the cost of thermal energy.

  17. Plasma-catalytic decomposition of TCE

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, A.; Morent, R.; De Geyter, N.; Leys, C. [Ghent Univ., Ghent (Belgium). Dept. of Applied Physics; Tuan, N.D.M.; Giraudon, J.M.; Lamonier, J.F. [Univ. des Sciences et Technologies de Lille, Villeneuve (France). Dept. de Catalyse et Chimie du Solide

    2010-07-01

    Volatile organic compounds (VOCs) are gaseous pollutants that pose an environmental hazard due to their high volatility and their possible toxicity. Conventional technologies to reduce the emission of VOCs have their advantages, but they become cost-inefficient when low concentrations have to be treated. In the past 2 decades, non-thermal plasma technology has received growing attention as an alternative and promising remediation method. Non-thermal plasmas are effective because they produce a series of strong oxidizers such as ozone, oxygen radicals and hydroxyl radicals that provide a reactive chemical environment in which VOCs are completely oxidized. This study investigated whether the combination of NTP and catalysis could improve the energy efficiency and the selectivity towards carbon dioxide (CO{sub 2}). Trichloroethylene (TCE) was decomposed by non-thermal plasma generated in a DC-excited atmospheric pressure glow discharge. The production of by-products was qualitatively investigated through FT-IR spectrometry. The results were compared with those from a catalytic reactor. The removal rate of TCE reached a maximum of 78 percent at the highest input energy. The by-products of TCE decomposition were CO{sub 2}, carbon monoxide (CO) hydrochloric acid (HCl) and dichloroacetylchloride. Combining the plasma system with a catalyst located in an oven downstream resulted in a maximum removal of 80 percent, at an energy density of 300 J/L, a catalyst temperature of 373 K and a total air flow rate of 2 slm. 14 refs., 6 figs.

  18. Low-temperature plasma modelling and simulation

    NARCIS (Netherlands)

    Dijk, van J.

    2011-01-01

    Since its inception in the beginning of the twentieth century, low-temperature plasma science has become a major ¿eld of science. Low-temperature plasma sources and gas discharges are found in domestic, industrial, atmospheric and extra-terrestrial settings. Examples of domestic discharges are those

  19. Influence of different preparation conditions on catalytic activity of ag /gama-al/sub 2/o/sub 3/ for hydrogenation of coal slime pyrolysis

    International Nuclear Information System (INIS)

    Lei, Z.; Rong, C.

    2014-01-01

    This paper, introducing variable conditional factors with Ag/AL/sub 2/O/sub 3/ as catalyst, selects five variables to investigate the influences of experimental conditions on Ag/Al2O/sub 3/ catalytic activity and define the optimal process conditions. These variables include Ag loading amount, calcinations temperature, calcinations time, reduction temperature, reduction time. X ray diffraction (XRD), hydrogen temperature-programmed reduction (TPR), X ray photoelectron spectrum (XPS) and scanning electron microscopy (SEM) were utilized to characterize the catalytic activity of Ag/-Al/sub 2/O/sub 3/, active center structure and state and those of carrier were emphatically studied, In the meantime the effects of active center and carrier on catalytic activity are studied. The results showed that: (1) In the range of 600 degree C-900 degree C, the catalytic activity of Ag/-Al/sub 2/O/sub 3/ with different loading showed little difference when changing loading amount, in the range of 900 degree C-1100 degree C, when the loading was 5%, the catalytic activity was very high; From the XRD and SEM characterizations, when the loading was 5%, it showed strong intensity diffraction peak of Ag crystal, crystal Ag is the most important activity center to promote hydrogen yield. (2) the catalytic activity of Ag/-Al/sub 2/O/sub 3/ at 450 degree C was considerably higher than that at 400 degree C and 500 degree C. By BET, XRD and SEM characterization, it can be seen, the diffraction peaks intensity of Ag crystal at 450 degree C is higher and sharper than that at 400 degree C and 500 degree C and with the increase of calcinations temperature, the specific surface area of catalysts also increased. (3) In the range of 600 degree C - 1000 degree C, the effects of calcinations time can be negligible, while, with temperature higher than 1000 degree C, 4-hour-calcinations-time catalyst exhibits a more noticeable catalytic activity than 3-hour and 5-hour catalyst do; From the XRD

  20. Catalytically-etched hexagonal boron nitride flakes and their surface activity

    International Nuclear Information System (INIS)

    Kim, Do-Hyun; Lee, Minwoo; Ye, Bora; Jang, Ho-Kyun; Kim, Gyu Tae; Lee, Dong-Jin; Kim, Eok-Soo; Kim, Hong Dae

    2017-01-01

    Highlights: • Hexagonal boron nitride flakes are etched at low temperature in air by catalysts. • The presence of transition metal oxides produces an etched structure in the flakes. • Etched surfaces become highly active due to vacancy defects formed in the flakes. - Abstract: Hexagonal boron nitride (h-BN) is a ceramic compound which is thermally stable up to 1000 °C in air. Due to this, it is a very challenging task to etch h-BN under air atmosphere at low temperature. In this study, we report that h-BN flakes can be easily etched by oxidation at 350 °C under air atmosphere in the presence of transition metal (TM) oxide. After selecting Co, Cu, and Zn elements as TM precursors, we simply oxidized h-BN sheets impregnated with the TM precursors at 350 °C in air. As a result, microscopic analysis revealed that an etched structure was created on the surface of h-BN flakes regardless of catalyst type. And, X-ray diffraction patterns indicated that the air oxidation led to the formation of Co_3O_4, CuO, and ZnO from each precursor. Thermogravimetric analysis showed a gradual weight loss in the temperature range where the weight of h-BN flakes increased by air oxidation. As a result of etching, pore volume and pore area of h-BN flakes were increased after catalytic oxidation in all cases. In addition, the surface of h-BN flakes became highly active when the h-BN samples were etched by Co_3O_4 and CuO catalysts. Based on these results, we report that h-BN flakes can be easily oxidized in the presence of a catalyst, resulting in an etched structure in the layered structure.

  1. Catalytically-etched hexagonal boron nitride flakes and their surface activity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do-Hyun, E-mail: nanotube@korea.ac.kr [School of Electrical Engineering, Korea University, 5-ga, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of); Lee, Minwoo; Ye, Bora [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of); Jang, Ho-Kyun; Kim, Gyu Tae [School of Electrical Engineering, Korea University, 5-ga, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of); Lee, Dong-Jin [New Functional Components Research Team, Korea Institute of Footware & Leather Technology, 152 Danggamseo-ro, Busanjin-gu, Busan 614-100 (Korea, Republic of); Kim, Eok-Soo [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of); Kim, Hong Dae, E-mail: hdkim@kitech.re.kr [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of)

    2017-04-30

    Highlights: • Hexagonal boron nitride flakes are etched at low temperature in air by catalysts. • The presence of transition metal oxides produces an etched structure in the flakes. • Etched surfaces become highly active due to vacancy defects formed in the flakes. - Abstract: Hexagonal boron nitride (h-BN) is a ceramic compound which is thermally stable up to 1000 °C in air. Due to this, it is a very challenging task to etch h-BN under air atmosphere at low temperature. In this study, we report that h-BN flakes can be easily etched by oxidation at 350 °C under air atmosphere in the presence of transition metal (TM) oxide. After selecting Co, Cu, and Zn elements as TM precursors, we simply oxidized h-BN sheets impregnated with the TM precursors at 350 °C in air. As a result, microscopic analysis revealed that an etched structure was created on the surface of h-BN flakes regardless of catalyst type. And, X-ray diffraction patterns indicated that the air oxidation led to the formation of Co{sub 3}O{sub 4}, CuO, and ZnO from each precursor. Thermogravimetric analysis showed a gradual weight loss in the temperature range where the weight of h-BN flakes increased by air oxidation. As a result of etching, pore volume and pore area of h-BN flakes were increased after catalytic oxidation in all cases. In addition, the surface of h-BN flakes became highly active when the h-BN samples were etched by Co{sub 3}O{sub 4} and CuO catalysts. Based on these results, we report that h-BN flakes can be easily oxidized in the presence of a catalyst, resulting in an etched structure in the layered structure.

  2. Synthesis, Characterization, and Catalytic Applications of Transition Metal Oxide/Carbonate Nanomaterials

    Science.gov (United States)

    Jin, Lei

    2011-12-01

    topic in this thesis presents studies of ethane oxydehydrogenation (ODH) in the presence of CO2 over the octahedral molecular sieve (OMS-2) catalyst. Conversion of CO2 into organic compounds has been studied intensively. Ethane catalytic oxydehydrogenation in the presence of CO2 offers an attractive route for converting CO2. In this study, using OMS-2 as the catalyst in C2H6 dehydrogenation in the presence of CO2 is an example where extreme conditions are used to drive high conversions of ethane (> 70%) and CO2 (up to 56%) with high selectivity towards ethylene (87%) with a short contact time (0.6 s). This inexpensive material also showed high stability during the process, and the presence of CO2 removed coke depositions throughout the catalyst. The results obtained from this study open up new possibilities for olefin dehydrogenations in the presence of CO2, a perfect feedstock for any process involving ethylene carbonylation with the recycling of the greenhouse gas. The fourth part of this thesis presents a ZnO/La2O2CO 3 composite prepared by a new and easy method and discusses the use of these materials as heterogeneous catalysts for ultra-fast microwave biodiesel production at low temperatures. The search for solid state materials with high catalytic activities is one of the key steps toward reducing the cost of producing biodiesel. We present a high biodiesel yield (> 95%) in less than 5 minutes under mild reaction conditions (industrial application of the synthesized ZnO/La2O2CO3 as a potential heterogeneous catalyst for fast biodiesel production, avoiding many of the issues found in both commercial and independently published catalysts. Following the fourth part of this thesis, the fifth part presents the synthesis and characterization of a series of rare earth Ln2O 2CO3 (Ln = La, Eu, Nd, and Sm) layered materials as novel basic materials for the biodiesel production. Reports on rare earth oxycarbonate Ln2O2CO3 (Ln = rare earths) layered materials as heterogeneous

  3. Applying the principles of thermoeconomics to the organic Rankine Cycle for low temperature waste heat recovery

    International Nuclear Information System (INIS)

    Xiao, F.; Lilun, Q.; Changsun, S.

    1989-01-01

    In this paper, thermoeconomic principle is used to study the selection of working fluids and the option of the cycle parameters in the organic Rankine cycle of low temperature waste heat recovery. The parameter ξ, the product of the ratio of waste heat recovery and real cycle thermal efficiency, is suggested as a unified thermodynamic criterion for the selection of the working fluids. The mathematical expressions are developed to determine the optimal boiling temperature and the optimal pin point temperature difference in the heat recovery exchanger by way of thermoeconomic principle

  4. Catalytic pyrolysis of microalgae to high-quality liquid bio-fuels

    International Nuclear Information System (INIS)

    Babich, I.V.; Hulst, M. van der; Lefferts, L.; Moulijn, J.A.; O'Connor, P.; Seshan, K.

    2011-01-01

    The pyrolytic conversion of chlorella algae to liquid fuel precursor in presence of a catalyst (Na 2 CO 3 ) has been studied. Thermal decomposition studies of the algae samples were performed using TGA coupled with MS. Liquid oil samples were collected from pyrolysis experiments in a fixed-bed reactor and characterized for water content and heating value. The oil composition was analyzed by GC-MS. Pretreatment of chlorella with Na 2 CO 3 influences the primary conversion of chlorella by shifting the decomposition temperature to a lower value. In the presence of Na 2 CO 3 , gas yield increased and liquid yield decreased when compared with non-catalytic pyrolysis at the same temperatures. However, pyrolysis oil from catalytic runs carries higher heating value and lower acidity. Lower content of acids in the bio-oil, higher aromatics, combined with higher heating value show promise for production of high-quality bio-oil from algae via catalytic pyrolysis, resulting in energy recovery in bio-oil of 40%. -- Highlights: → The pyrolytic catalytic conversion of chlorella algae to liquid fuel precursor. → Na 2 CO 3 as a catalyst for the primary conversion of chlorella. → Pyrolysis oil from catalytic runs carries higher heating value and lower acidity. → High-quality bio-oil from algae via catalytic pyrolysis with energy recovery in bio-oil of 40%.

  5. In situ formed catalytically active ruthenium nanocatalyst in room temperature dehydrogenation/dehydrocoupling of ammonia-borane from Ru(cod)(cot) precatalyst.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ayvalı, Tuğçe; Philippot, Karine

    2012-03-20

    The development of simply prepared and effective catalytic materials for dehydrocoupling/dehydrogenation of ammonia-borane (AB; NH(3)BH(3)) under mild conditions remains a challenge in the field of hydrogen economy and material science. Reported herein is the discovery of in situ generated ruthenium nanocatalyst as a new catalytic system for this important reaction. They are formed in situ during the dehydrogenation of AB in THF at 25 °C in the absence of any stabilizing agent starting with homogeneous Ru(cod)(cot) precatalyst (cod = 1,5-η(2)-cyclooctadiene; cot = 1,3,5-η(3)-cyclooctatriene). The preliminary characterization of the reaction solutions and the products was done by using ICP-OES, ATR-IR, TEM, XPS, ZC-TEM, GC, EA, and (11)B, (15)N, and (1)H NMR, which reveal that ruthenium nanocatalyst is generated in situ during the dehydrogenation of AB from homogeneous Ru(cod)(cot) precatalyst and B-N polymers formed at the initial stage of the catalytic reaction take part in the stabilization of this ruthenium nanocatalyst. Moreover, following the recently updated approach (Bayram, E.; et al. J. Am. Chem. Soc.2011, 133, 18889) by performing Hg(0), CS(2) poisoning experiments, nanofiltration, time-dependent TEM analyses, and kinetic investigation of active catalyst formation to distinguish single metal or in the present case subnanometer Ru(n) cluster-based catalysis from polymetallic Ru(0)(n) nanoparticle catalysis reveals that in situ formed Ru(n) clusters (not Ru(0)(n) nanoparticles) are kinetically dominant catalytically active species in our catalytic system. The resulting ruthenium catalyst provides 120 total turnovers over 5 h with an initial turnover frequency (TOF) value of 35 h(-1) at room temperature with the generation of more than 1.0 equiv H(2) at the complete conversion of AB to polyaminoborane (PAB; [NH(2)BH(2)](n)) and polyborazylene (PB; [NHBH](n)) units.

  6. Improvement in low-temperature and instantaneous high-rate output performance of Al-free AB5-type hydrogen storage alloy for negative electrode in Ni/MH battery: Effect of thermodynamic and kinetic regulation via partial Mn substituting

    Science.gov (United States)

    Zhou, Wanhai; Zhu, Ding; Tang, Zhengyao; Wu, Chaoling; Huang, Liwu; Ma, Zhewen; Chen, Yungui

    2017-03-01

    A series of Al-free Mn-modified AB5-type hydrogen storage alloys have been designed and the effects of thermodynamic stability and electrochemical kinetics on electrochemical performance via Mn substituting have been investigated. Compared with high-Al alloys, the Al-free alloys in this study have better low-temperature performance and instantaneous high-rate output because of the higher surface catalytic ability. After partial substitution of Ni by Mn, both the hydrogen desorption capacity and plateau pressure decrease, and correspondingly results in an improved thermodynamic stability which is adverse to low-temperature delivery. Additionally, with the improvement of charge acceptance ability and anti-corrosion property via Mn substitution, the room-temperature discharge capacity and cycling stability increase slightly. However, Mn adversely affects the electrochemical kinetics and deteriorates both the surface catalytic ability and the bulk hydrogen diffusion ability, leading to the drop of low-temperature dischargeability, high-rate dischargeability and peak power (Ppeak). Based on the thermodynamic and kinetic regulation and overall electrochemical properties, the optimal composition is obtained when x = 0.2, the discharge capacity is 243.6 mAh g-1 at -40 °C with 60 mA g-1, and the Ppeak attains to 969.6 W kg-1 at -40 °C.

  7. Highly anisotropic SmCo{sub 5} nanoflakes by surfactant-assisted ball milling at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lidong; Zhang, Songlin [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Zhang, Jian, E-mail: zhangj@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Ping Liu, J. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Xia, Weixing; Du, Juan; Yan, Aru [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Yi, Jianhong [Institute of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Li, Wei; Guo, Zhaohui [Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081 (China)

    2015-01-15

    Surfactant-assisted ball milling (SABM) has been shown to be a promising method for preparing rare earth-transition metal (RE-TM) nanoflakes and nanoparticles. In this work, we prepared SmCo{sub 5} nanoflakes by SABM at low temperature, and 2-methyl pentane and trioctylamine were specially selected as solvent and surfactant, respectively, due to their low melting points. The effects of milling temperature on the morphology, microstructure and magnetic performance of SmCo{sub 5} nanoflakes were investigated systematically. Comparing with the samples milled at room temperature, the SmCo{sub 5} nanoflakes prepared at low temperature displayed more homogeneous morphology and lower oxygen content. Remarkably, better crystallinity, better grain alignment and larger remanence ratio were shown in the samples milled at low temperature, which resulted from the distinct microstructure caused by low milling temperature. The differences in structural evolution between the SmCo{sub 5} nanoflakes milled at room temperature and low temperature, including the formation of nanocrystalline, grain boundary sliding, grain rotation, et al., were discussed. It was found that lowering the temperature of SABM was a powerful method for the fabrication of RE-TM nanoflakes, which showed better hard magnetic properties and lower oxygen content. This was important for the preparation of high-performance sintered magnets, bonded magnets and nanocomposite magnets. - Highlights: • We prepare SmCo{sub 5} nanoflakes by surfactant-assisted ball milling at low temperature. • Better grain alignment and higher remanence ratio are achieved. • The oxygen content is reduced by lowering the milling temperature. • A distinct microstructural evolution caused by low milling temperature is clarified.

  8. Ultrahigh-sensitive detection of molecules produced in catalytic reactions by uni-atomic-composition bi-element clusters supported on solid substrate

    International Nuclear Information System (INIS)

    Yasumatsu, H; Fukui, N

    2013-01-01

    An apparatus has been developed for measuring catalytic activities of uni-atomic-composition bi-element clusters supported on a solid substrate. The cluster sample is prepared by irradiating a cluster-ion beam having the uni-atomic composition onto the substrate on a soft-landing condition in an ultra-high vacuum. The catalytic activity is measured by temperature-programmed desorption (TPD) mass analysis. Molecules at a density as low as 3 cm −3 have been detected with an ultrahigh-sensitive TPD mass spectrometer consisting of a cylindrical electron gun, a quadrupole mass filter and a micro-channel-plate ion-detector. The high reproducibility has been achieved by careful calibration of the TPD mass spectrometer. As a benchmark example, thermal oxidation of CO catalysed on Pt 30 disks supported on a silicon surface was studied. The CO 2 products have been successfully observed at the Pt 30 density as low as 3 × 10 12 clusters in a circular area of 8 mm in diameter at the ramping rate of the sample temperature as low as 0.3 K s −1 .

  9. Hydrogen generator, via catalytic partial oxidation of methane for fuel cells

    Science.gov (United States)

    Recupero, Vincenzo; Pino, Lidia; Di Leonardo, Raffaele; Lagana', Massimo; Maggio, Gaetano

    It is well known that the most acknowledged process for generation of hydrogen for fuel cells is based upon the steam reforming of methane or natural gas. A valid alternative could be a process based on partial oxidation of methane, since the process is mildly exothermic and therefore not energy intensive. Consequently, great interest is expected from conversion of methane into syngas, if an autothermal, low energy intensive, compact and reliable process could be developed. This paper covers the activities, performed by the CNR Institute of Transformation and Storage of Energy (CNR-TAE), on theoretical and experimental studies for a compact hydrogen generator, via catalytic selective partial oxidation of methane, integrated with second generation fuel cells (EC-JOU2 contract). In particular, the project focuses the attention on methane partial oxidation via heterogeneous selective catalysts, in order to: demonstrate the basic catalytic selective partial oxidation of methane (CSPOM) technology in a subscale prototype, equivalent to a nominal output of 5 kWe; develop the CSPOM technology for its application in electric energy production by means of fuel cells; assess, by a balance of plant analysis, and a techno-economic evaluation, the potential benefits of the CSPOM for different categories of fuel cells.

  10. Determination of surface coverage of catalysts : temperature programmed experiments on platinum and iridium sponge catalysts after low temperature ammonia oxidation

    NARCIS (Netherlands)

    van den Broek, A.C.M.; Grondelle, van J.; Santen, van R.A.

    1999-01-01

    The activity of iridium and platinum sponge catalysts was studied in the low temperature gas phase oxidation of ammonia with oxygen. Under the reaction conditions used, iridium was found to be more active and more selective to nitrogen than platinum. Furthermore it was established from activity

  11. Efficient low-temperature soot combustion by bimetallic Ag-Cu/SBA-15 catalysts.

    Science.gov (United States)

    Wen, Zhaojun; Duan, Xinping; Hu, Menglin; Cao, Yanning; Ye, Linmin; Jiang, Lilong; Yuan, Youzhu

    2018-02-01

    In this study, the effects of copper (Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag-Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5Ag 1 -Cu 0.1 /SBA-15 catalyst, on which the soot combustion starts at T ig =225°C with a T 50 =285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C (Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag-Cu nanolloy particles, downsizing the mean particle size from 3.7nm in monometallic catalyst to 2.6nm in bimetallic Ag-Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance. Copyright © 2017. Published by Elsevier B.V.

  12. Non-Catalytic and MgSO4 - Catalyst based Degradation of Glycerol in Subcritical and Supercritical Water Media

    Directory of Open Access Journals (Sweden)

    Mahfud Mahfud

    2011-02-01

    Full Text Available This research aims to study the glycerol degradation reaction in subcritical and supercritical water media. The degradation of glycerol into other products was performed both with sulphate salt catalysts and without catalyst. The reactant was made from glycerol and water with the mass ratio of 1:10. The experiments were carried out using a batch reactor at a constant pressure of 250 kgf/cm2, with the temperature range of 200-400oC, reaction time of 30 minutes, and catalyst mol ratio in glycerol of 1:10 and 1:8. The products of the non-catalytic glycerol degradation were acetaldehyde, methanol, and ethanol. The use of sulphate salt as catalyst has high selectivity to acetaldehyde and still allows the formation alcohol product in small quantities. The mechanism of ionic reaction and free radical reaction can occur at lower temperature in hydrothermal area or subcritical water. Conversion of glycerol on catalytic reaction showed a higher yield when compared with the reaction performed without catalyst

  13. Decentralized substations for low-temperature district heating with no Legionella risk, and low return temperatures

    International Nuclear Information System (INIS)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    To improve energy efficiency and give more access to renewable energy sources, low-temperature district heating (LTDH) is a promising concept to be realized in the future. However, concern about Legionella proliferation restricts applying low-temperature district heating in conventional systems with domestic hot water (DHW) circulation. In this study, a system with decentralized substations was analysed as a solution to this problem. Furthermore, a modification for the decentralized substation system were proposed in order to reduce the average return temperature. Models of conventional system with medium-temperature district heating, decentralized substation system with LTDH, and innovative decentralized substation system with LTDH were built based on the information of a case building. The annual distribution heat loss and the operating costs of the three scenarios were calculated and compared. From the results, realizing LTDH by the decentralized substation unit, 30% of the annual distribution heat loss inside the building can be saved compared to a conventional system with medium-temperature district heating. Replacing the bypass pipe with an in-line supply pipe and a heat pump, the innovative decentralized substation system can reduce distribution heat loss by 39% compared to the conventional system and by 12% compared to the normal decentralized substation system with bypass. - Highlights: • The system of decentralized substations can realize low-temperature district heating without running the risk of Legionella. • Decentralized substations help reduce the distribution heat loss inside the building compared to conventional system. • A new concept that can reduce the return temperature for district heating is proposed and analysed.

  14. Lipoxygenase in Caragana jubata responds to low temperature, abscisic acid, methyl jasmonate and salicylic acid.

    Science.gov (United States)

    Bhardwaj, Pardeep Kumar; Kaur, Jagdeep; Sobti, Ranbir Chander; Ahuja, Paramvir Singh; Kumar, Sanjay

    2011-09-01

    Lipoxygenase (LOX) catalyses oxygenation of free polyunsaturated fatty acids into oxylipins, and is a critical enzyme of the jasmonate signaling pathway. LOX has been shown to be associated with biotic and abiotic stress responses in diverse plant species, though limited data is available with respect to low temperature and the associated cues. Using rapid amplification of cDNA ends, a full-length cDNA (CjLOX) encoding lipoxygenase was cloned from apical buds of Caragana jubata, a temperate plant species that grows under extreme cold. The cDNA obtained was 2952bp long consisting of an open reading frame of 2610bp encoding 869 amino acids protein. Multiple alignment of the deduced amino acid sequence with those of other plants demonstrated putative LH2/ PLAT domain, lipoxygenase iron binding catalytic domain and lipoxygenase_2 signature sequences. CjLOX exhibited up- and down-regulation of gene expression pattern in response to low temperature (LT), abscisic acid (ABA), methyl jasmonate (MJ) and salicylic acid (SA). Among all the treatments, a strong up-regulation was observed in response to MJ. Data suggests an important role of jasmonate signaling pathway in response to LT in C. jubata. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Catalytic steam reforming of ethanol for hydrogen production: Brief status

    Directory of Open Access Journals (Sweden)

    Bineli Aulus R.R.

    2016-01-01

    Full Text Available Hydrogen represents a promising fuel since it is considered as a cleanest energy carrier and also because during its combustion only water is emitted. It can be produced from different kinds of renewable feedstocks, such as ethanol, in this sense hydrogen could be treated as biofuel. Three chemical reactions can be used to achieve this purpose: the steam reforming (SR, the partial oxidation (POX and the autothermal reforming (ATR. In this study, the catalysts implemented in steam reforming of ethanol were reviewed. A wide variety of elements can be used as catalysts for this reaction, such as base metals (Ni, Cu and Co or noble metals (Rh, Pt and Ru usually deposited on a support material that increases surface area and improves catalytic function. The use of Rh, Ni and Pt supported or promoted with CeO2, and/or La2O3 shows excellent performance in ethanol SR catalytic process. The ratio of water to ethanol, reaction temperatures, catalysts loadings, selectivity and activity are also discussed as they are extremely important for high hydrogen yields.

  16. Selectivity of an Active Natural Zeolite in Catalytic Conversion Process of Bangkirai, Kruing and Kamper Woods Biofuel to Gasoline Fraction

    Directory of Open Access Journals (Sweden)

    Wega Trisunaryanti

    2010-06-01

    Full Text Available The selectivity of an active natural zeolite (ZAAH in catalytic conversion process of Bangkirai, Kruing and Kamper woods biofuels has been studied. The ZAAH catalyst was prepared from a natural zeolite (ZA treated with acids solution (1% HF and 6M HCI and hydrothermal then calcined at 500 °C and oxidized at 400 °C under nitrogen and oxygen gas stream, respectively. Characterizations of the catalysts including Si/Al ratio and acidity were determined by atomic adsorption spectroscopy (AAS and ammonia gas adsorption method, respectively. The conversion process was carried out in a flow reactor system at 400 °C, under N2 stream (20 mL/min. The biofuel was vaporized from the pyrolysis zone to the catalytic reactor. A liquid product was covered and analyzed by gas chromatograph (GC and that connected with mass spectroscopy (GC-MS. The characterization results showed that the Si/AI ratio and acidity of the ZAAH were higher than that of the ZA catalyst. The GC-MS data showed that the highest product selectivity was 2,4-dimethyl heptane and 1,2-dimethyl benzene. The total product selectivity using the ZAAH catalyst (bangkirai = 68.10%; kruing = 54.76%; kamper = 50.72% was higher than that of the ZA catalyst (bangkirai = 39.24%; kruing = 44.38%; kamper = 46.11%.

  17. Formation of imines by selective gold-catalysed aerobic oxidative coupling of alcohols and amines under ambient conditions

    DEFF Research Database (Denmark)

    Kegnæs, Søren; Mielby, Jerrik Jørgen; Mentzel, Uffe Vie

    2010-01-01

    with excellent selectivity (above 98%) at moderate conversion under optimized conditions. The effect of catalytic amounts of different bases was studied, along with reaction temperature and time. Utilisation of a selective catalyst system that uses dioxygen as an oxidant and only produces water as by...

  18. Nitrogen removal from wastewater by a catalytic oxidation method.

    Science.gov (United States)

    Huang, T L; Macinnes, J M; Cliffe, K R

    2001-06-01

    The ammonia-containing waste produced in industries is usually characterized by high concentration and high temperature, and is not treatable by biological methods directly. In this study, a hydrophobic Pt/SDB catalyst was first used in a trickle-bed reactor to remove ammonia from wastewater. In the reactor, both stripping and catalytic oxidation occur simultaneously. It was found that higher temperature and higher oxygen partial pressure enhanced the ammonia removal. A reaction pathway, which involves oxidizing ammonia to nitric oxide, which then further reacts with ammonia to produce nitrogen and water, was confirmed. Small amounts of by-products, nitrites and nitrates were also detected in the resultant reaction solution. These compounds came from the absorption of nitrogen oxides. Both the minimum NO2- selectivity and maximum ammonia removal were achieved when the resultant pH of treated water was near 7.5 for a feed of unbuffered ammonia solution.

  19. Absolute Molecular Orientation of Isopropanol at Ceria (100) Surfaces: Insight into Catalytic Selectivity from the Interfacial Structure

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, Benjamin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Goverapet Srinivasan, Sriram [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Indian Inst. of Technology (IIT), Rajasthan (India); Bryantsev, Vyacheslav S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Dongkyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Ho Nyung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ma, Ying-Zhong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lutterman, Daniel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-12

    The initial mechanistic steps underlying heterogeneous chemical catalysis can be described in a framework where the composition, structure, and orientation of molecules adsorbed to reactive interfaces are known. However, extracting this vital information is the limiting step in most cases due in part to challenges in probing the interfacial monolayer with enough chemical specificity to characterize the surface molecular constituents. These challenges are exacerbated at complex or spatially heterogeneous interfaces where competing processes and a distribution of local environments can uniquely drive chemistry. To address these limitations, this work presents a distinctive combination of materials synthesis, surface specific optical experiments, and theory to probe and understand molecular structure at catalytic interfaces. Specifically, isopropanol was adsorbed to surfaces of the model CeO2 catalyst that were synthesized with only the (100) facet exposed. Vibrational sum-frequency generation was used to probe the molecular monolayer, and with the guidance of density functional theory calculations, was used to extract the structure and absolute molecular orientation of isopropanol at the CeO2 (100) surface. Our results show that isopropanol is readily deprotonated at the surface, and through the measured absolute molecular orientation of isopropanol, we obtain new insight into the selectivity of the (100) surface to form propylene. Our findings reveal key insight into the chemical and physical phenomena taking place at pristine interfaces thereby pointing to intuitive structural arguments to describe catalytic selectivity in more complex systems.

  20. Applications of Low Density Flow Techniques and Catalytic Recombination at the Johnson Space Center

    Science.gov (United States)

    Scott, Carl D.

    2000-01-01

    The talk presents a brief background on defInitions of catalysis and effects associated with chemically nonequilibrium and low-density flows of aerospace interest. Applications of catalytic recombination on surfaces in dissociated flow are given, including aero heating on reentry spacecraft thermal protection surfaces and reflection of plume flow on pressure distributions associated with the space station. Examples include aero heating predictions for the X-38 test vehicle, the inlet of a proposed gas-sampling probe used in high enthalpy test facilities, and a parabolic body at angle of attack. The effect of accommodation coefficients on thruster induced pressure distributions is also included. Examples of tools used include simple aero heating formulas based on boundary layer solutions, an engineering approximation that uses axisymmetric viscous shock layer flow to simulate full three dimensional flow, full computational fluid dynamics, and direct simulation Monte-Carlo calculations. Methods of determining catalytic recombination rates in arc jet flow are discus ed. An area of catalysis not fully understood is the formation of single-wall carbon nanotubes (SWNT) with gas phase or nano-size metal particles. The Johnson Space Center is making SWNTs using both a laser ablation technique and an electric arc vaporization technique.

  1. PARAMETRIC EVALUATION OF VOC CONVERSION VIA CATALYTIC INCINERATION

    Directory of Open Access Journals (Sweden)

    Kaskantzis Neto G.

    1997-01-01

    Full Text Available Abstract - A pilot-scale catalytic incineration system was used to investigate the effectiveness of catalytic incineration as a means of reducing volatile organic compound (VOC air pollutants. The objectives of the study were: 1 to investigate the effects of operating and design variables on the reduction efficiency of VOCs; and 2 to evaluate reduction efficiencies for specific compounds in different chemical classes. The study results verified that the following factors affect the catalyst performance: inlet temperature, space velocity, compound type, and compound inlet concentration. Tests showed that reduction efficiencies exceeding 98% were possible, given sufficiently high inlet gas temperatures for the following classes of compounds: alcohols, acetates, ketones, hydrocarbons, and aromatics

  2. Surface single-molecule dynamics controlled by entropy at low temperatures

    Science.gov (United States)

    Gehrig, J. C.; Penedo, M.; Parschau, M.; Schwenk, J.; Marioni, M. A.; Hudson, E. W.; Hug, H. J.

    2017-02-01

    Configuration transitions of individual molecules and atoms on surfaces are traditionally described using an Arrhenius equation with energy barrier and pre-exponential factor (attempt rate) parameters. Characteristic parameters can vary even for identical systems, and pre-exponential factors sometimes differ by orders of magnitude. Using low-temperature scanning tunnelling microscopy (STM) to measure an individual dibutyl sulfide molecule on Au(111), we show that the differences arise when the relative position of tip apex and molecule changes by a fraction of the molecule size. Altering the tip position on that scale modifies the transition's barrier and attempt rate in a highly correlated fashion, which results in a single-molecular enthalpy-entropy compensation. Conversely, appropriately positioning the STM tip allows selecting the operating point on the compensation line and modifying the transition rates. The results highlight the need to consider entropy in transition rates of single molecules, even at low temperatures.

  3. The conversion of anaerobic digestion waste into biofuels via a novel Thermo-Catalytic Reforming process.

    Science.gov (United States)

    Neumann, Johannes; Meyer, Johannes; Ouadi, Miloud; Apfelbacher, Andreas; Binder, Samir; Hornung, Andreas

    2016-01-01

    Producing energy from biomass and other organic waste residues is essential for sustainable development. Fraunhofer UMSICHT has developed a novel reactor which introduces the Thermo-Catalytic Reforming (TCR®) process. The TCR® is a process which can convert any type of biomass and organic feedstocks into a variety of energy products (char, bio-oil and permanent gases). The aim of this work was to demonstrate this technology using digestate as the feedstock and to quantify the results from the post reforming step. The temperature of a post reformer was varied to achieve optimised fuel products. The hydrogen rich permanent gases produced were maximised at a post reforming temperature of 1023 K. The highly de-oxygenated liquid bio-oil produced contained a calorific value of 35.2 MJ/kg, with significantly improved fuel physical properties, low viscosity and acid number. Overall digestate showed a high potential as feedstock in the Thermo-Catalytic Reforming to produce pyrolysis fuel products of superior quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Low temperature study of nonstoichiometric titanium carbide

    International Nuclear Information System (INIS)

    Tashmetov, M.Yu.

    2005-05-01

    By low temperature neutron diffraction method was studied structure in nonstoichiometric titanium carbide from room temperature up to 12K. It is found of low temperature phase in titanium carbide- TiC 0.71 . It is established region and borders of this phase. It is determined change of unit cell parameter. (author)

  5. The Role of Solvent Polarity on Low-Temperature Methanol Synthesis Catalyzed by Cu Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahoba-Sam, Christian [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway); Olsbye, Unni [Department of Chemistry, University of Oslo, Oslo (Norway); Jens, Klaus-Joachim, E-mail: Klaus.J.Jens@usn.no [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway)

    2017-07-14

    Methanol syntheses at low temperature in a liquid medium present an opportunity for full syngas conversion per pass. The aim of this work was to study the role of solvents polarity on low-temperature methanol synthesis reaction using eight different aprotic polar solvents. A “once through” catalytic system, which is composed of Cu nanoparticles and sodium methoxide, was used for methanol synthesis at 100°C and 20 bar syngas pressure. Solvent polarity rather than the 7–10 nm Cu (and 30 nm Cu on SiO{sub 2}) catalyst used dictated trend of syngas conversion. Diglyme with a dielectric constant (ε) = 7.2 gave the highest syngas conversion among the eight different solvents used. Methanol formation decreased with either increasing or decreasing solvent ε value of diglyme (ε = 7.2). To probe the observed trend, possible side reactions of methyl formate (MF), the main intermediate in the process, were studied. MF was observed to undergo two main reactions; (i) decarbonylation to form CO and MeOH and (ii) a nucleophilic substitution to form dimethyl ether and sodium formate. Decreasing polarity favored the decarbonylation side reaction while increasing polarity favored the nucleophilic substitution reaction. In conclusion, our results show that moderate polarity solvents, e.g., diglyme, favor MF hydrogenolysis and, hence, methanol formation, by retarding the other two possible side reactions.

  6. Methanol induces low temperature resilient methanogens and improves methane generation from domestic wastewater at low to moderate temperatures.

    Science.gov (United States)

    Saha, Shaswati; Badhe, Neha; De Vrieze, Jo; Biswas, Rima; Nandy, Tapas

    2015-01-01

    Low temperature (methanol is a preferred substrate by methanogens in cold habitats. The study hypothesizes that methanol can induce the growth of low-temperature resilient, methanol utilizing, hydrogenotrophs in UASB reactor. The hypothesis was tested in field conditions to evaluate the impact of seasonal temperature variations on methane yield in the presence and absence of methanol. Results show that 0.04% (v/v) methanol increased methane up to 15 times and its effect was more pronounced at lower temperatures. The qPCR analysis showed the presence of Methanobacteriales along with Methanosetaceae in large numbers. This indicates methanol induced the growth of both the hydrogenotrophic and acetoclastic groups through direct and indirect routes, respectively. This study thus demonstrated that methanol can impart resistance in methanogenic biomass to low temperature and can improve performance of UASB reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Measured Performance of a Low Temperature Air Source Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R. K. [Johnson Research LLC, Pueblo West, CO (United States)

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor 'boosted heat pump' technology. The Low Temperature Heat Pumpsystem operates with four increasing levels of capacity (heat output) as the outdoor temperature drops. The system was shown to select capacity correctly, supplying the appropriate amount of heat to the house across the full range of outdoor temperatures. The system's Coefficient of Performance (Seasonal COP, or SCOP) over two entire winters was calculated, based on measured data, to be 3.29over the first winter and 2.68 over the second winter. A second seasonal efficiency calculation by a different method yielded a SCOP of 2.78 for the first winter and 2.83 for the second winter. This second seasonal efficiency calculation was determined by comparing measured heat pump energy use to the in situ energy use with resistance heat alone. This method is the ratio of the slopes of thedaily energy use load lines.

  8. Low temperature magnetic structure of MnSe

    Indian Academy of Sciences (India)

    Abstract. In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport prop- erties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase ...

  9. Low-temperature mobility measurements on CMOS devices

    International Nuclear Information System (INIS)

    Hairpetian, A.; Gitlin, D.; Viswanathan, C.R.

    1989-01-01

    The surface channel mobility of carriers in eta- and rho-MOS transistors fabricated in a CMOS process was accurately determined at low temperatures down to 5 Κ. The mobility was obtained by an accurate measurement of the inversion charge density using a split C-V technique and the conductance at low drain voltages. The split C-V technique was validated at all temperatures using a one-dimensional Poisson solver (MOSCAP), which was modified for low-temperature application. The mobility dependence on the perpendicular electric field for different substrate bias values appears to have different temperature dependence for eta- and rho-channel devices. The electron mobility increases with a decrease in temperature at all gate voltages. On the other hand, the hole mobility exhibits a different temperature behavior depending upon whether the gate voltage corresponds to strong inversion or is near threshold

  10. Formation of alkanes alkylcycloalkanes and alkylbenzenes during the catalytic hydrocracking of vegetable oils

    Energy Technology Data Exchange (ETDEWEB)

    Filho, G.N. da Rocha; Brodzki, D.; Djega-Mariadassou, G. (Universite Pierre et Marie Curie, Paris (France). Lab. Reactivite de Surface et Structure)

    1993-04-01

    Catalytic hydrocracking of vegetable oils was performed in the presence of a NiMo/[gamma]-Al[sub 2]O[sub 3] catalyst sulfided in situ with elemental sulfur under hydrogen pressure. Various vegetable oils were selected to study the effect of the degree of saturation and lateral chain length: [ital Passiflora edulis] (maracuja), [ital Astrocaryum vulgare] (tucuma), [ital Mauritia flexuosa] (buriti), [ital Orbygnya martiana] (babassu) and soybean. The effects of reaction temperature and hydrogen pressure in cyclization were studied. Carboxylic acids were used as model compounds. 29 refs., 5 figs., 5 tabs.

  11. Catalytic Conversion of Glucose into 5-Hydroxymethylfurfural by Hf(OTf4 Lewis Acid in Water

    Directory of Open Access Journals (Sweden)

    Junjie Li

    2015-12-01

    Full Text Available A series of Lewis acidic metal salts were used for glucose dehydration to 5-hydroymethylfurfural (HMF in water. Effect of valence state, ionic radii of Lewis acidic cation, and the type of anions on the catalytic performance have been studied systematically. The experimental results showed that the valence state played an important role in determining catalytic activity and selectivity. It was found that a higher glucose conversion rate and HMF selectivity could be obtained over high valent Lewis acid salts, where the ionic radii of these Lewis acidic metal salts are usually relatively small. Analysis on the effect of the anions of Lewis acid salts on the catalytic activity and the selectivity suggested that a higher glucose conversion and HMF selectivity could be readily obtained with Cl−. Furthermore, the recyclability of high valence state Lewis acid salt was also studied, however, inferior catalytic performance was observed. The deactivation mechanism was speculated to be the fact that high valence state Lewis acid salt was comparatively easier to undergo hydrolysis to yield complicated metal aqua ions with less catalytic activity. The Lewis acidic activity could be recovered by introducing a stoichiometric amount of hydrochloric acid (HCl to the catalytic before the reaction.

  12. Effects of temperature and feed composition on catalytic dehydration of methanol to dimethyl ether over {gamma}-alumina

    Energy Technology Data Exchange (ETDEWEB)

    Freshteh Raoof; Majid Taghizadeh; Ali Eliassi; Fereydoon Yaripour [Babol University of Technology, Babol (Iran). Chemical Engineering Department

    2008-10-15

    Catalytic dehydration of methanol to dimethyl ether (DME) is performed in an adiabatic fixed bed heterogeneous reactor by using acidic {gamma}-alumina. By changing the mean average temperature of the catalyst bed (or operating temperature of the reactor) from 233 up to 303{sup o}C, changes in methanol conversion were monitored. The results showed that the conversion of methanol strongly depended on the reactor operating temperature. Also, conversion of pure methanol and mixture of methanol and water versus time were studied and the effect of water on deactivation of the catalyst was investigated. The results revealed that when pure methanol was used as the process feed, the catalyst deactivation occurred very slowly. But, by adding water to the feed methanol, the deactivation of the {gamma}-alumina was increased very rapidly; so much that, by increasing water content to 20 weight percent by weight, the catalyst lost its activity by about 12.5-fold more than in the process with pure methanol. Finally, a temperature dependent model developed to predict pure methanol conversion to DME correlates reasonably well with experimental data. 11 refs., 9 figs., 3 tabs.

  13. Highly selective deuteration of pharmaceutically relevant nitrogen-containing heterocycles: a flow chemistry approach.

    Science.gov (United States)

    Ötvös, Sándor B; Mándity, István M; Fülöp, Ferenc

    2011-08-01

    A simple and efficient flow-based technique is reported for the catalytic deuteration of several model nitrogen-containing heterocyclic compounds which are important building blocks of pharmacologically active materials. A continuous flow reactor was used in combination with on-demand pressure-controlled electrolytic D(2) production. The D(2) source was D(2)O, the consumption of which was very low. The experimental set-up allows the fine-tuning of pressure, temperature, and flow rate so as to determine the optimal conditions for the deuteration reactions. The described procedure lacks most of the drawbacks of the conventional batch deuteration techniques, and additionally is highly selective and reproducible.

  14. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications

    International Nuclear Information System (INIS)

    Dong Wenjun; Huang Huandi; Zhu Yanjun; Li Xiaoyun; Wang Xuebin; Li Chaorong; Chen Benyong; Wang Ge; Shi Zhan

    2012-01-01

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide–amine intermediate and Ag + at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO 3 nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag–MoO 3 nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature. (paper)

  15. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications.

    Science.gov (United States)

    Dong, Wenjun; Huang, Huandi; Zhu, Yanjun; Li, Xiaoyun; Wang, Xuebin; Li, Chaorong; Chen, Benyong; Wang, Ge; Shi, Zhan

    2012-10-26

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide-amine intermediate and Ag(+) at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO(3) nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag-MoO(3) nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature.

  16. Mechanical pumping at low temperature

    International Nuclear Information System (INIS)

    Perin, J.P.; Claudet, G.; Disdier, F.

    1995-01-01

    This novel concept consist of a mechanical pump able to run at low temperature (25K). Since gas density varies inversely with temperature, this pump would deliver much higher mass flow rate than at room temperature for a given size. Advantages of this concept are order of magnitude reduction in size, weight, when compared to a conventional pump scaled to perform the same mass flow rate at room temperature. This pump would be a solution to allow continuously tritium extraction and minimize the mass inventory. (orig.)

  17. Parametric study on catalytic tri-reforming of methane for syngas production

    International Nuclear Information System (INIS)

    Chein, Rei-Yu; Wang, Chien-Yu; Yu, Ching-Tsung

    2017-01-01

    A two-dimensional numerical model for syngas production from tri-reforming of methane (TRM) in adiabatic tubular fixed-bed reactors was established. From the results obtained, it was found that reactant must be preheated to certain temperatures for TRM activation. Although the delay factor accounting for the varying catalytic bed activities produced different temperature and species mole fraction profiles in the reactor upstream, the reactor performance was delay factor independent if the reactor outlet results were used because nearly identical temperature and species mole fraction variations were obtained at the reactor downstream. The numerical results also indicated that reverse water-gas shift reaction plays an important role for H 2 and CO yields. With higher O 2 in reactant, high temperature resulted, leading to lower H 2 /CO ratio. The absence of H 2 O in the reactant caused dry reforming of methane as the dominant reaction, resulting in H 2 /CO ratio close to unity. With the absence of CO 2 in the reactant, steam reforming of methane was the dominant reaction, resulting in H 2 /CO ratio close to 3. Using flue gas from combustion as TRM feedstock, it was found that H 2 /CO ratio was enhanced using lower CH 4 amount in reactant. High-temperature flue gas was suggested for TRM for the activation requirement. - Highlights: • Reactant must be preheated to certain temperature for tri-reforming of methane (TRM) activation. • A delay factor is used to account for varying catalytic activity. • TRM performance is delay factor independent when reactor outlet results are used. • Water-gas shift reaction plays an important role in H 2 yield, CO yield and H 2 /CO ratio in TRM. • Low CH 4 and high temperature are suggested when flue gas is used in TRM.

  18. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium....

  19. 环戊二烯基钌配合物催化的高选择性苯乙炔二聚反应%HIGHLY SELECTIVE CATALYTIC DIMERIZATION OF PHENYLACETYLENE BY CYCLOPENTADIENYL RUTHENIUM COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    金军挺; 黄吉玲; 陶晓春; 钱延龙

    1999-01-01

    @@ Transition metal vinylidene complexes (M=C=CHR) have attracted a great deal of attention in recent years as a new type of organometallic intermediates that may have unusual reactivity[1]. Their reactivity has been explored and their application to organic synthesis is developed[2]. Recent reports on the ruthenium-vinylidene complexes[3]suggest that the reaction of ruthenium-vinylidene complexes with a base generates the coordinatively unsaturated ruthenium acetylide species, which are involved in a number of catalytic and stoichiometric reactions of alkynes. For example,the coordinatively unsaturated ruthenium acetylide species C5Me5Ru(PPh3)-C≡CPh,formed from the reaction of the vinylidene complex C5Me5Ru(PPh3) (Cl)=C=CHPh with a base was reactive toward a variety of small molecules and active in catalytic dimerization of terminal alkynes[4]. The dimerization of terminal alkyne is an effective method of forming enynes, but its synthetic application in organic synthesis has been limited dueto low selectivity for dimeric products[5]. In this communication, we report that three ruthenium complexes were used as catalysts for the highly selective dimerization of phenylacetylene.

  20. Temperature Characteristics of Monolithically Integrated Wavelength-Selectable Light Sources

    International Nuclear Information System (INIS)

    Han Liang-Shun; Zhu Hong-Liang; Zhang Can; Ma Li; Liang Song; Wang Wei

    2013-01-01

    The temperature characteristics of monolithically integrated wavelength-selectable light sources are experimentally investigated. The wavelength-selectable light sources consist of four distributed feedback (DFB) lasers, a multimode interferometer coupler, and a semiconductor optical amplifier. The oscillating wavelength of the DFB laser could be modulated by adjusting the device operating temperature. A wavelength range covering over 8.0nm is obtained with stable single-mode operation by selecting the appropriate laser and chip temperature. The thermal crosstalk caused by the lateral heat spreading between lasers operating simultaneously is evaluated by oscillating-wavelength shift. The thermal crosstalk approximately decreases exponentially as the increasing distance between lasers

  1. Staged catalytic gasification/steam reforming of pyrolysis oil

    NARCIS (Netherlands)

    van Rossum, G.; Kersten, Sascha R.A.; van Swaaij, Willibrordus Petrus Maria

    2009-01-01

    Gasification/steam reforming of pyrolysis oil was studied in a staged reactor concept, which consisted of an inert fluidized bed and a catalytic fixed bed. Methane and C2−C3 free syngas is produced at a single temperature around 800 °C at atmospheric pressure. By lowering the temperature of the

  2. Plastic responses to elevated temperature in low and high elevation populations of three grassland species.

    Science.gov (United States)

    Frei, Esther R; Ghazoul, Jaboury; Pluess, Andrea R

    2014-01-01

    Local persistence of plant species in the face of climate change is largely mediated by genetic adaptation and phenotypic plasticity. In species with a wide altitudinal range, population responses to global warming are likely to differ at contrasting elevations. In controlled climate chambers, we investigated the responses of low and high elevation populations (1200 and 1800 m a.s.l.) of three nutrient-poor grassland species, Trifolium montanum, Ranunculus bulbosus, and Briza media, to ambient and elevated temperature. We measured growth-related, reproductive and phenological traits, evaluated differences in trait plasticity and examined whether trait values or plasticities were positively related to approximate fitness and thus under selection. Elevated temperature induced plastic responses in several growth-related traits of all three species. Although flowering phenology was advanced in T. montanum and R. bulbosus, number of flowers and reproductive allocation were not increased under elevated temperature. Plasticity differed between low and high elevation populations only in leaf traits of T. montanum and B. media. Some growth-related and phenological traits were under selection. Moreover, plasticities were not correlated with approximate fitness indicating selectively neutral plastic responses to elevated temperature. The observed plasticity in growth-related and phenological traits, albeit variable among species, suggests that plasticity is an important mechanism in mediating plant responses to elevated temperature. However, the capacity of species to respond to climate change through phenotypic plasticity is limited suggesting that the species additionally need evolutionary adaptation to adjust to climate change. The observed selection on several growth-related and phenological traits indicates that the study species have the potential for future evolution in the context of a warming climate.

  3. Hydrogen metal hydride storage with integrated catalytic recombiner for mobile application

    Energy Technology Data Exchange (ETDEWEB)

    Marinescu-Pasoi, L.; Behrens, U.; Langer, G.; Gramatte, W.; Rastogi, A.K.; Schmitt, R.E. (Battelle-Institut e.V., Frankfurt am Main (DE). Dept. of Energy Technology)

    1991-01-01

    A novel, thermodynamically efficient device is under development at Battelle in Frankfurt, by which the range of hydrogen-driven cars with a metal hydride tank might be roughly doubled. The device makes use of the properties of metal hydrides, combined with catalytic combustion. Its development is funded by the Hessian Ministry of Economic Affairs and Technology; it is to be completed by the end of 1990. High-temperature hydrides (HTH) have about three times the storage capacity of low temperature hydrides (LTH), but require relatively large amounts of heat at high temperatures to release the hydrogen. The exhaust heat from combustion-engine-driven vehicles is insufficient for this, and vehicles with electric (fuel cell) drive produce practically no exhaust heat at all. The Battelle-developed device is a combination of an HTH storage cell, an LTH storage cell and a catalyst. (author).

  4. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane; Reduction catalytique selective des oxydes d'azote (NO{sub x}) provenant d'effluents gazeux industriels par l'hydrogene ou le methane

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann Pirez, M

    2004-12-15

    This work deals with the selective catalytic reduction of nitrogen oxides (NO{sub x}), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N{sub 2}, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO{sub 3}, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  5. Low temperature CVD growth of ultrathin carbon films

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2016-05-01

    Full Text Available We demonstrate the low temperature, large area growth of ultrathin carbon films by chemical vapor deposition under atmospheric pressure on various substrates. In particularly, uniform and continuous carbon films with the thickness of 2-5 nm were successfully grown at a temperature as low as 500 oC on copper foils, as well as glass substrates coated with a 100 nm thick copper layer. The characterizations revealed that the low-temperature-grown carbon films consist on few short, curved graphene layers and thin amorphous carbon films. Particularly, the low-temperature grown samples exhibited over 90% transmittance at a wavelength range of 400-750 nm and comparable sheet resistance in contrast with the 1000oC-grown one. This low-temperature growth method may offer a facile way to directly prepare visible ultrathin carbon films on various substrate surfaces that are compatible with temperatures (500-600oC used in several device processing technologies.

  6. The Low Temperature Microgravity Physics Facility Project

    Science.gov (United States)

    Chui, T.; Holmes, W.; Lai, A.; Croonquist, A.; Eraker, J.; Abbott, R.; Mills, G.; Mohl, J.; Craig, J.; Balachandra, B.; hide

    2000-01-01

    We describe the design and development of the Low Temperature Microgravity Physics Facility, which is intended to provide a unique environment of low temperature and microgravity for the scientists to perform breakthrough investigations on board the International Space Station.

  7. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-03-08

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  8. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-09-06

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  9. System and method for controlling ammonia levels in a selective catalytic reduction catalyst using a nitrogen oxide sensor

    Science.gov (United States)

    None

    2017-07-25

    A system according to the principles of the present disclosure includes an air/fuel ratio determination module and an emission level determination module. The air/fuel ratio determination module determines an air/fuel ratio based on input from an air/fuel ratio sensor positioned downstream from a three-way catalyst that is positioned upstream from a selective catalytic reduction (SCR) catalyst. The emission level determination module selects one of a predetermined value and an input based on the air/fuel ratio. The input is received from a nitrogen oxide sensor positioned downstream from the three-way catalyst. The emission level determination module determines an ammonia level based on the one of the predetermined value and the input received from the nitrogen oxide sensor.

  10. Results of radiation tests at cryogenic temperature on some selected organic materials for the LHC

    International Nuclear Information System (INIS)

    Schoenbacher, H.; Szeless, B.; Tavlet, M.; Humer, K.; Weber, H.W.

    1996-01-01

    Future multi-TeV particle accelerators like the CERN Large Hadron Collider (LHC) will use superconducting magnets where organic materials will be exposed to high radiation levels at temperatures as low as 2 K. A representative selection of organic materials comprising insulating films, cable insulations, and epoxy-type impregnated resins were exposed to neutron and gamma radiation of a nuclear reactor. Depending on the type of materials, the integrated radiation doses varied between 180 kGy and 155 MGy. During irradiation, the samples were kept close to the boiling temperature of liquid nitrogen i.e. ∼ 80 K and thereafter stored in liquid nitrogen and transferred at the same temperature into the testing device for measurement of tensile and flexural strength. Tests were carried out on the same materials at similar dose rates at room temperature, and the results were compared with those obtained at cryogenic temperature. They show that, within the selected dose range, a number of organic materials are suitable for use in the radiation field of the LHC at cryogenic temperature. (orig.)

  11. Crystal structures and catalytic performance of three new methoxy substituted salen type nickel(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine

    Science.gov (United States)

    Ghaffari, Abolfazl; Behzad, Mahdi; Pooyan, Mahsa; Amiri Rudbari, Hadi; Bruno, Giuseppe

    2014-04-01

    Three new nickel(II) complexes of a series of methoxy substituted salen type Schiff base ligands were synthesized and characterized by IR, UV-Vis and 1H NMR spectroscopy and elemental analysis. The ligands were synthesized from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with n-methoxysalicylaldehyde (n = 3, 4 and 5). Crystal structures of these complexes were determined. Electrochemical behavior of the complexes was studied by means of cyclic voltammetry in DMSO solutions. Catalytic performance of the complexes was studied in the epoxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxidant under various conditions to find the optimum operating parameters. Low catalytic activity with moderate epoxide selectivity was observed in in-solvent conditions but in the solvent-free conditions, enhanced catalytic activity with high epoxide selectivity was achieved.

  12. High-efficiency plasma catalytic removal of dilute benzene from air

    International Nuclear Information System (INIS)

    Fan, Hong-Yu; Shi, Chuan; Li, Xiao-Song; Zhao, De-Zhi; Xu, Yong; Zhu, Ai-Min

    2009-01-01

    Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min -1 flow rate, the energy cost was as low as 3.7 x 10 -3 kWh m -3 air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

  13. Development of a syngas-fired catalytic combustion system for hybrid solar-thermal applications

    International Nuclear Information System (INIS)

    Gupta, Mayank; Pramanik, Santanu; Ravikrishna, R.V.

    2016-01-01

    Highlights: • Syngas-fired combustor concept as hybrid heat source for solar thermal application. • Experimental characterization of catalytic combustor under fuel-rich conditions. • Stable operation, quick startup, and high turn-down ratio demonstrated. • Reacting flow CFD simulations of single channel of catalytic monolith. - Abstract: This paper describes the development and operation of a catalytic combustion system for use with syngas as an important component of a hybrid heating source for solar-thermal power generation. The reactor consists of a cylindrical ceramic monolith with porous alumina washcoat in which platinum is distributed as the catalyst. Two fuel-rich equivalence ratios were studied over a range of flow rates. The fuel-rich conditions permit low temperature combustion without the problem of hotspots likely to occur under fuel-lean conditions with hydrogen-containing fuels. Experimental data of temperature and species concentration at the exit of the reactor have been reported for a maximum fuel thermal input of 34 kW. The system exhibited quick start-up with a light-off time of around 60 s and a steady-state time of around 200 s as determined from the transient temperature profiles. The experimental results have also been complemented with detailed two-dimensional numerical simulations for improved understanding of the combustion characteristics in the reactor. The simulations suggest that the combustion system can be operated at a turn-down ratios far in excess of 1.67, which is the maximum value that has been investigated in the present setup. Stable operation, quick startup, and high turn-down ratio are some of the key features that enable the proposed combustion system to accommodate the transients in solar-thermal applications.

  14. Biomass-to-hydrogen via fast pyrolysis and catalytic steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Chornet, E.; Wang, D.; Czernik, S. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-10-01

    Pyrolysis of lignocellulosic biomass and reforming the pyroligneous oils is being studied as a strategy for producing hydrogen. Novel technologies for the rapid pyrolysis of biomass have been developed in the past decade. They provide compact and efficient systems to transform biomass into vapors that are condensed to oils, with yields as high as 75-80 wt.% of the anhydrous biomass. This {open_quotes}bio-oil{close_quotes} is a mixture of aldehydes, alcohols, acids, oligomers from the constitutive carbohydrates and lignin, and some water derived from the dehydration reactions. Hydrogen can be produced by reforming the bio-oil or its fractions with steam. A process of this nature has the potential to be cost competitive with conventional means of producing hydrogen. The reforming facility can be designed to handle alternate feedstocks, such as natural gas and naphtha, if necessary. Thermodynamic modeling of the major constituents of the bio-oil has shown that reforming is possible within a wide range of temperatures and steam-to-carbon ratios. Existing catalytic data on the reforming of oxygenates have been studied to guide catalyst selection. Tests performed on a microreactor interfaced with a molecular beam mass spectrometer showed that, by proper selection of the process variables: temperature, steam-to-carbon ratio, gas hourly space velocity, and contact time, almost total conversion of carbon in the feed to CO and CO{sub 2} could be obtained. These tests also provided possible reaction mechanisms where thermal cracking competes with catalytic processes. Bench-scale, fixed bed reactor tests demonstrated high hydrogen yields from model compounds and carbohydrate-derived pyrolysis oil fractions. Reforming bio-oil or its fractions required proper dispersion of the liquid to avoid vapor-phase carbonization of the feed in the inlet to the reactor. A special spraying nozzle injector was designed and successfully tested with an aqueous fraction of bio-oil.

  15. High electro-catalytic activities of glucose oxidase embedded one-dimensional ZnO nanostructures

    International Nuclear Information System (INIS)

    Sarkar, Nirmal K; Bhattacharyya, Swapan K

    2013-01-01

    One-dimensional ZnO nanorods and nanowires are separately synthesized on Zn substrate by simple hydrothermal processes at low temperatures. Electro-catalytic responses of glucose oxidase/ZnO/Zn electrodes using these two synthesized nanostructures of ZnO are reported and compared with others available in literature. It is apparent the Michaelis–Menten constant, K M app , for the present ZnO nanowire, having a greater aspect ratio, is found to be the lowest when compared with others. This sensor shows lower oxidation peak potential with a long detection range of 6.6 μM–380 mM and the highest sensitivity of ∼35.1 μA cm −2 mM −1 , among the reported values in the literature. Enzyme catalytic efficiency and turnover numbers are also found to be remarkably high. (paper)

  16. Catalytic reduction of NO{sub x} in gasoline engine exhaust over copper- and nickel-exchanged X-zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, S. [Indian Inst. of Technology, Kharagpur (India). Dept. of Mechanical Engineering; Das, R.K. [Indian School of Mines, Dhanbad (India). Dept. of Engineering and Mining Machinery

    2001-10-11

    Catalytic removal of NO{sub x} in engine exhaust gases can be accomplished by non-selective reduction, selective reduction and decomposition. Noble metals are extensively used for non-selective reduction of NO{sub x} and up to 90% of engine NO{sub x} emissions can be reduced in a stoichiometric exhaust. This requirement of having the stoichiometric fuel-air ratio acts against efficiency improvement of engines. Selective NO{sub x} reduction in the presence of different reductants such as, NH{sub 3}, urea or hydrocarbons, requires close control of the amount of reductant being injected which otherwise may be emitted as a pollutant. Catalytic decomposition is the best option for NO{sub x} removal. Nevertheless, catalysts which are durable, economic and active for NO{sub x} reduction at normal engine exhaust temperature ranges are still being investigated. Three catalysts based on X-zeolite have been developed by exchanging the Na+ ion with copper, nickel and copper-nickel metal ions and applied to the exhaust of a stationary gasoline engine to explore their potential for catalytic reduction of NO{sub x} under a wide range of engine and exhaust conditions. Some encouraging results have been obtained. The catalyst Cu-X exhibits much better NO{sub x} reduction performance at any temperature in comparison to Cu-Ni-X and Ni-X; while Cu-Ni-X catalyst exhibits slightly better performance than Ni-X catalyst. Maximum NO{sub x} efficiency achieved with Cu-X catalyst is 59.2% at a space velocity (sv) of 31 000 h{sup -1}; while for Cu-Ni-X and Ni-X catalysts the equivalent numbers are 60.4% and 56% respectively at a sv of 22 000 h{sup -1}. Unlike noble metals, the doped X-zeolite catalysts exhibit significant NO{sub x} reduction capability for a wide range of air/fuel ratio and with a slower rate of decline as well with increase in air/fuel ratio. (author)

  17. Petrochemical promoters in catalytic cracking

    International Nuclear Information System (INIS)

    Gomez, Maria; Vargas, Clemencia; Lizcano, Javier

    2010-01-01

    This study is based on the current scheme followed by a refinery with available Catalytic Cracking capacity to process new feedstocks such as Straight Run Naphtha and Naphthas from FCC. These feedstocks are of petrochemical interest to produce Ethane, Ethylene, Propylene, i-Butane, Toluene and Xylene. To evaluate the potential of these new streams versus the Cracking-charged Residues, it was performed a detailed chemical analysis on the structural groups in carbons [C1-C12] at the reactor product obtained in pilot plant. A catalyst with and without Propylene Promoter Additive was used. This study analyzes the differences in the chemical composition of the feedstocks, relating them to the yield of each petrochemical product. Straight Run Naphthas with a high content of Naphthenes, and Paraffines n[C5-C12] and i[C7-C12] are selective to the production of i-Butane and Propane, while Naphthas from FCC with a high content of n[C5-C12]Olefins, i-Olefins, and Aromatics are more selective to Propylene, Toluene, and Xylene. Concerning Catalytic Cracking of Naphthas, the Additive has similar selectivity for all the petrochemical products, their yields increase by about one point with 4%wt of Additive, while in cracking of Residues, the Additive increases in three points Propylene yield, corresponding to a selectivity of 50% (?C3= / ?LPG).

  18. Design and modeling of low temperature solar thermal power station

    International Nuclear Information System (INIS)

    Shankar Ganesh, N.; Srinivas, T.

    2012-01-01

    Highlights: ► The optimum conditions are different for efficiency and power conditions. ► The current model works up to a maximum separator temperature of 150 °C. ► The turbine concentration influences the high pressure. ► High solar beam radiation and optimized cycle conditions give low collector cost. -- Abstract: During the heat recovery in a Kalina cycle, a binary aqua–ammonia mixture changes its state from liquid to vapor, the more volatile ammonia vaporizes first and then the water starts vaporization to match temperature profile of the hot fluid. In the present work, a low temperature Kalina cycle has been investigated to optimize the heat recovery from solar thermal collectors. Hot fluid coming from solar parabolic trough collector with vacuum tubes is used to generate ammonia rich vapor in a boiler for power generation. The turbine inlet conditions are optimized to match the variable hot fluid temperature with the intermittent nature of the solar radiation. The key parameters discussed in this study are strong solution concentration, separator temperature which affects the hot fluid inlet temperature and turbine ammonia concentration. Solar parabolic collector system with vacuum tubes has been designed at the optimized power plant conditions. This work can be used in the selection of boiler, separator and turbine conditions to maximize the power output as well as efficiency of power generation system. The current model results a maximum limit temperature for separator as 150 °C at the Indian climatic conditions. A maximum specific power of 105 kW per kg/s of working fluid can be obtained at 80% of strong solution concentration with 140 °C separator temperature. The corresponding plant and cycle efficiencies are 5.25% and 13% respectively. But the maximum efficiencies of 6% and 15% can be obtained respectively for plant and Kalina cycle at 150 °C of separator temperature.

  19. A novel low-temperature-active β-glucosidase from symbiotic Serratia sp. TN49 reveals four essential positions for substrate accommodation.

    Science.gov (United States)

    Zhou, Junpei; Zhang, Rui; Shi, Pengjun; Huang, Huoqing; Meng, Kun; Yuan, Tiezheng; Yang, Peilong; Yao, Bin

    2011-10-01

    A 2,373-bp full-length gene (bglA49) encoding a 790-residue polypeptide (BglA49) with a calculated mass of 87.8 kDa was cloned from Serratia sp. TN49, a symbiotic bacterium isolated from the gut of longhorned beetle (Batocera horsfieldi) larvae. The deduced amino acid sequence of BglA49 showed the highest identities of 80.1% with a conceptually translated protein from Pantoea sp. At-9b (EEW02556), 38.3% with the identified glycoside hydrolase (GH) family 3 β-glucosidase from Clostridium stercorarium NCBI 11754 (CAB08072), and sp. G5 (ABL09836) and Paenibacillus sp. C7 (AAX35883). The recombinant enzyme (r-BglA49) was expressed in Escherichia coli and displayed the typical characteristics of low-temperature-active enzymes, such as low temperature optimum (showing apparent optimal activity at 35°C), activity at low temperatures (retaining approximately 60% of its maximum activity at 20°C and approximately 25% at 10°C). Compared with the thermophilic GH 3 β-glucosidase, r-BglA49 had fewer hydrogen bonds and salt bridges and less proline residues. These features might relate to the increased structure flexibility and higher catalytic activity at low temperatures of r-BglA49. The molecular docking study of four GH 3 β-glucosidases revealed five conserved positions contributing to substrate accommodation, among which four positions of r-BglA49 (R192, Y228, D260, and E449) were identified to be essential based on site-directed mutagenesis analysis.

  20. Measuring Poisson Ratios at Low Temperatures

    Science.gov (United States)

    Boozon, R. S.; Shepic, J. A.

    1987-01-01

    Simple extensometer ring measures bulges of specimens in compression. New method of measuring Poisson's ratio used on brittle ceramic materials at cryogenic temperatures. Extensometer ring encircles cylindrical specimen. Four strain gauges connected in fully active Wheatstone bridge self-temperature-compensating. Used at temperatures as low as liquid helium.

  1. The catalytic cracking mechanism of lignite pyrolysis char on tar

    International Nuclear Information System (INIS)

    Lei, Z.; Huibin, H.; Xiangling, S.; Zhenhua, M.; Lei, Z.

    2017-01-01

    The influence of different pyrolysis conditions for tar catalytic cracking will be analyzed according to the lignite pyrolysis char as catalyst on pyrolytic tar in this paper. The pyrolysis char what is the by-product of the cracking of coal has an abundant of pore structure and it has good catalytic activity. On this basis, making the modified catalyst when the pyrolysis char is activation and loads Fe by impregnation method. The cracking mechanism of lignite pyrolytic tar is explored by applying gas chromatograph to analyze splitting products of tar. The experimental results showed that: (1) The effect of tar cracking as the pyrolysis temperature, the heating rate, the volatilization of pyrolysis char and particle size increasing is better and better. The effect of the catalytic and cracking of lignite pyrolysis char in tar is best when the heating rate, the pyrolysis temperature, the volatiles of pyrolysis char, particle size is in specific conditions.(2) The activation of pyrolysis char can improve the catalytic effect of pyrolysis char on the tar cracking. But it reduces the effect of the tar cracking when the pyrolysis char is activation loading Fe. (author)

  2. Sweating at low temperature

    International Nuclear Information System (INIS)

    Chalaye, H.; Launay, J.P.

    1980-11-01

    Tests of penetration liquids normally used between 10 and 40 0 C have shown that the arrangement of operationaal conditions (penetration and revealing times) was not sufficient to maintain their sensitivity below 10 0 C, thereby confirming that this temperature is a limit below which such products cannot be employed. The results achieved with a penetrant and a tracer specially devised for low temperatures (SHERWIN B 305 + D100) are satisfactory between 0 0 C and 15 0 C [fr

  3. Potential application of palladium nanoparticles as selective recyclable hydrogenation catalysts

    International Nuclear Information System (INIS)

    Mukherjee, DebKumar

    2008-01-01

    The search for more efficient catalytic systems that might combine the advantages of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis is one of the most exciting challenges of modern chemistry. More recently with the advances of nanochemistry, it has been possible to prepare soluble analogues of heterogeneous catalysts. These nanoparticles are generally stabilized against aggregation into larger particles by electrostatic or steric protection. Herein we demonstrate the use of room temperature ionic liquid for the stabilization of palladium nanoparticles that are recyclable catalysts for the hydrogenation of carbon-carbon double bonds and application of these catalysts to the selective hydrogenation of internal or terminal C=C bonds in unsaturated primary alcohols. The particles suspended in room temperature ionic liquid show no metal aggregation or loss of catalytic activity even on prolonged use

  4. Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects

    Science.gov (United States)

    Tarabanko, Valery E.; Tarabanko, Nikolay

    2017-01-01

    This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15%) inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali) in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed. PMID:29140301

  5. Low-temperature self-assembled vertically aligned carbon nanofibers as counter-electrode material for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Mahpeykar, S M; Tabatabaei, M K; Ghafoori-fard, H; Habibiyan, H; Koohsorkhi, J

    2013-01-01

    Low-temperature AC–DC PECVD is employed for direct growth of vertically aligned carbon nanofibers (VACNFs) on ordinary transparent conductive glass as counter-electrode material for dye-sensitized solar cells (DSSCs). To the best of our knowledge, this is the first report on utilization of VACNFs grown directly on ordinary FTO-coated glass as a cost-effective catalyst material in DSSCs. According to the FESEM images, the as-grown arrays are well aligned and dense, and offer uniform coverage on the surface of the substrate. In-plane and out-of-plane conductivity measurements reveal their good electrical conductivity, and Raman spectroscopy suggests a high number of electrocatalytic active sites, favoring charge transport at the electrolyte/electrode interface. Hybrid VACNF/Pt electrodes are also fabricated for performance comparison with Pt and VACNF electrodes. X-ray diffraction results verify the crystallization of Pt in hybrid electrodes and further confirm the vertical alignment of carbon nanofibers. Electrochemical characterization indicates that VACNFs provide both high catalytic and good charge transfer capability, which can be attributed to their high surface area, defect-rich and one-dimensional structure, vertical alignment and low contact resistance. As a result, VACNF cells can achieve a comparable performance (∼5.6%) to that of the reference Pt cells (∼6.5%). Moreover, by combination of the excellent charge transport and catalytic ability of VACNFs and the high conductivity of Pt nanoparticles, hybrid VACNF/Pt cells can deliver a performance superior to that of the Pt cells (∼7.2%), despite having a much smaller amount of Pt loading, which raises hopes for low-cost large-scale production of DSSCs in the future. (paper)

  6. The influence of desilication on high-silica MFI and its catalytic performance for N2O decomposition

    Science.gov (United States)

    Shen, Qun; Wu, Minfang; Wang, Hui; Sun, Nannan; He, Chi; Wei, Wei

    2018-05-01

    A series of MFI zeolites with different Si/Al ratios were pretreated by a basic solution and their catalytic activity was evaluated in N2O decomposition after iron exchange. The performance of Fe-ZSM-5 catalysts could be improved by alkaline pretreatment. Among these samples, the activity curve of Fe-Z5-250-S sample could move to low temperature by >100 °C with a good preservation of hydrothermal stability. It is found that with the meso-microporous hybrid structure, the content of iron as active metal is significantly increased. Additionally, well preservation of the chemical environment around the tetrahedral aluminum and the site accessibility probably may be the other important factors to influence the catalytic activity.

  7. Low temperature safety of lithium-thionyl chloride cells

    Science.gov (United States)

    Subbarao, S.; Deligiannis, F.; Shen, D. H.; Dawson, S.; Halpert, G.

    The use of lithium thionyl chloride cells for low-temperature applications is presently restricted because of their unsafe behavior. An attempt is made in the present investigation to identify the safe/unsafe low temperature operating conditions and to understand the low temperature cell chemistry responsible for the unsafe behavior. Cells subjected to extended reversal at low rate and -40 C were found to explode upon warm-up. Lithium was found to deposit on the carbon cathodes during reversal. Warming up to room temperature may be accelerating the lithium corrosion in the electrolyte. This may be one of the reasons for the cell thermal runaway.

  8. Fiscal 1998 achievement report on regional consortium research and development project. Venture business fostering regional consortium research and development in its 2nd year--Creation of key industries (Development of energy-efficient catalytic decomposition device for persistent halogen compounds for environmental conservation); 1998 nendo kankyo hozen no tame no nanbunkaisei halogen kagobutsu no sho energy shokubai bunkai sochi no kaihatsu seika hokokusho. 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Devices that decompose halogen compounds by use of AlPO{sub 4} are built, and studies are made concerning the collection of basic knowledge and findings, the settlement of problems that accompany scaleup, and the elucidation of mechanism of catalytic function occurrence. Tests are conducted at an intermediate plant, when catalytic performance is observed using a unit accommodating 1 liter of catalyst and chlorofluorocarbon (CFC) 12 is subjected to decomposition for the selection of proper operating conditions. Results similar to those from micro-reactor operation are attained when the reaction tube temperature is controlled. On the basis of the results, a real reactor and reaction system are designed and constructed, and CFC12 containing some CFC115 and CFC22 is made to undergo a decomposition reaction in this real reactor. It is then clarified that CFC catalytic decomposition proceeds at a low cost without generating dioxins and that therefore the process is commercially viable. In the study of catalytic adjustment, it is found that adjustment may be sufficiently effected when baking is conducted at 1,000 degrees C even when the extrusion process which demands low manufacturing cost is employed. Studies are also conducted about the mechanism of co-catalytic function occurrence. (NEDO)

  9. Low-temperature abatement of toluene over Mn-Ce oxides catalysts synthesized by a modified hydrothermal approach

    Science.gov (United States)

    Du, Jinpeng; Qu, Zhenping; Dong, Cui; Song, Lixin; Qin, Yuan; Huang, Na

    2018-03-01

    Mn-Ce oxides catalysts were synthesized by a novel method combining redox-precipitation and hydrothermal approach. The results indicate that the ratio between manganese and cerium plays a crucial role in the formation of catalysts, and the textual properties as well as catalytic activity are remarked affected. Mn0.6Ce0.4O2 possesses a predominant catalytic activity in the oxidation of toluene, over 70% of toluene is converted at 200 °C, and the complete conversion temperature is 210 °C. The formation of Mn-Ce solid solution markedly improves the surface area as well as pore volume of Mn-Ce oxide catalyst, and Mn0.6Ce0.4O2 possesses the largest surface area of 298.5 m2/g. The abundant Ce3+ and Mn3+ on Mn0.6Ce0.4O2 catalyst facilitate the formation of oxygen vacancies, and improve the transfer of oxygen in the catalysts. Meanwhile, it is found that cerium in Mn-Ce oxide plays a key role in the adsorption of toluene, while manganese is proved to be crucial in the oxidation of toluene, the cooperation between manganese and cerium improves the catalytic reaction process. In addition, the reaction process is investigated by in situ DRIFT measurement, and it is found that the adsorbed toluene could be oxidized to benzyl alcohol as temperature rises around 80-120 °C that can be further be oxidized to benzoic acid. Then benzoic acid could be decomposed to formate and/or carbonate species as temperature rises to form CO2 and H2O. In addition, the formed by-product phenol could be further oxidized into CO2 and H2O when the temperature is high enough.

  10. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  11. Partial substitution of manganese with cerium in SrMnO_3 nano-perovskite catalyst. Effect of the modification on the catalytic combustion of dilute acetone

    International Nuclear Information System (INIS)

    Rezlescu, Nicolae; Rezlescu, Elena; Popa, Paul Dorin; Doroftei, Corneliu; Ignat, Maria

    2016-01-01

    Ultrafine SrMn_1_−_xCe_xO_3 (x = 0, 02) perovskites were prepared by self-combustion method and heat treatment at 1000 °C for 4 h. The structure and surface properties were investigated by X-ray powder diffraction, scanning electron microscopy (SEM), EDX spectroscopy, and BET analysis. The catalyst properties of the perovskite nanopowders were tested in the catalytic combustion of dilute acetone at atmospheric pressure. The results revealed that the partial substitution of Mn by Ce ions (x = 0.2) in perovskite structure of SrMnO_3 had significantly improved catalytic activity of the perovskite. The SrMn_0_._8Ce_0_,_2O_3 perovskite composition can be a good candidate for catalytic combustion of low concentration acetone (1–2‰ in air) at low temperatures. The acetone conversion over this catalyst exceeds 90% at 200 °C, whereas over SrMnO_3 it is only 50%. Compared with SrMnO_3, T_5_0 is decreased by 75 °C and T_9_0 is decreased by 70 °C. The enhancement of the catalytic activity at a Ce doping of 0.2 may be ascribed to smaller crystallite sizes, larger specific surface area and the presence of Ce and Mn cations with variable valence in the perovskite structure. - Highlights: • A non-conventional method was used to make nanostructured perovskite samples. • XRD study confirms perovskite structure and nanosize of crystallites. • EDX analyses confirm homogeneity and purity of the samples. • The catalytic testing was carried out in the flameless combustion of dilute acetone. • SrMn_0_._8Ce_0_._2O_3 perovskite can be a promising catalyst for acetone combustion at low temperature.

  12. Environmentally friendly synthesis of CeO2 nanoparticles for the catalytic oxidation of benzyl alcohol to benzaldehyde and selective detection of nitrite.

    Science.gov (United States)

    Tamizhdurai, P; Sakthinathan, Subramanian; Chen, Shen-Ming; Shanthi, K; Sivasanker, S; Sangeetha, P

    2017-04-13

    Cerium oxide nanoparticles (CeO 2 NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO 2 NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO 2 NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO 2 NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO 2 NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO 2 NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO 2 NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02-1200 μM), low limit of detection (0.21 μM) and higher sensitivity (1.7238 μAμM -1 cm -2 ). However, the CeO 2 NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO 2 NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite.

  13. Investigation on CO catalytic oxidation reaction kinetics of faceted perovskite nanostructures loaded with Pt

    KAUST Repository

    Yin, S. M.

    2017-01-18

    Perovskite lead titanate nanostructures with specific {111}, {100} and {001} facets exposed, have been employed as supports to investigate the crystal facet effect on the growth and CO catalytic activity of Pt nanoparticles. The size, distribution and surface chemical states of Pt on the perovskite supports have been significantly modified, leading to a tailored conversion temperature and catalytic kinetics towards CO catalytic oxidation.

  14. Investigation on CO catalytic oxidation reaction kinetics of faceted perovskite nanostructures loaded with Pt

    KAUST Repository

    Yin, S. M.; Duanmu, J. J.; Zhu, Yihan; Yuan, Y. F.; Guo, S. Y.; Yang, J. L.; Ren, Z. H.; Han, G. R.

    2017-01-01

    Perovskite lead titanate nanostructures with specific {111}, {100} and {001} facets exposed, have been employed as supports to investigate the crystal facet effect on the growth and CO catalytic activity of Pt nanoparticles. The size, distribution and surface chemical states of Pt on the perovskite supports have been significantly modified, leading to a tailored conversion temperature and catalytic kinetics towards CO catalytic oxidation.

  15. Low irradiance photocatalytic degradation of toluene in air by screen-printed titanium dioxide layers

    International Nuclear Information System (INIS)

    Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Sangiorgi, Alex; Schiavi, Luca

    2013-01-01

    Screen-printed titania photocatalytic layers made from Degussa P25 were studied in order to assess the potential of this deposition technology for the production of catalytic surfaces for airborne pollutant degradation. The deposited catalytic TiO 2 layers were characterized by a low density (about 25% of the titania bulk crystal) typical of very porous films. The study was carried out using toluene at low concentration (12 ppb) as model pollutant and with a low UV-A irradiance level on the sample surface (200 μW cm −2 ). The catalyst layers were deposited on alumina and quartz substrates demonstrating a good catalytic depollution activity. The relationship between the layer thickness and the catalytic activity was studied in the 1 to 6.8 μm range indicating an optimal 3–4 μm film thickness. Thicker layers do not show significant increases in the catalytic activity. The optical transmittance was studied using quartz substrate samples, showing a severely reduced photon flux for layers deeper than 5 μm. The effect of post-printing thermal treatment was studied in the 500–900 °C range, demonstrating good catalytic activity for processing temperatures ≤ 700 °C. These results indicate that the screen-printing process can be a promising technology for the realization of high efficiency photocatalytic materials for air depollution applications at low UV-A irradiance. - Highlights: • Screen-printed TiO 2 has a good catalytic activity in toluene air depollution. • The overall density of screen-printed TiO 2 layer is ∼ 25% of the bulk crystal density. • The catalytic activity is demonstrated at low UV-A irradiance (200 µW cm –2 ). • The catalytic activity is dependent on the layer thickness until ∼ 4 µm thickness. • The catalytic layer has good activity up to 700 °C post-printing thermal treatment

  16. Cooperation between catalytic and DNA binding domains enhances thermostability and supports DNA synthesis at higher temperatures by thermostable DNA polymerases.

    Science.gov (United States)

    Pavlov, Andrey R; Pavlova, Nadejda V; Kozyavkin, Sergei A; Slesarev, Alexei I

    2012-03-13

    We have previously introduced a general kinetic approach for comparative study of processivity, thermostability, and resistance to inhibitors of DNA polymerases [Pavlov, A. R., et al. (2002) Proc. Natl. Acad. Sci. U.S.A.99, 13510-13515]. The proposed method was successfully applied to characterize hybrid DNA polymerases created by fusing catalytic DNA polymerase domains with various sequence-nonspecific DNA binding domains. Here we use the developed kinetic analysis to assess basic parameters of DNA elongation by DNA polymerases and to further study the interdomain interactions in both previously constructed and new chimeric DNA polymerases. We show that connecting helix-hairpin-helix (HhH) domains to catalytic polymerase domains can increase thermostability, not only of DNA polymerases from extremely thermophilic species but also of the enzyme from a faculatative thermophilic bacterium Bacillus stearothermophilus. We also demonstrate that addition of Topo V HhH domains extends efficient DNA synthesis by chimerical polymerases up to 105 °C by maintaining processivity of DNA synthesis at high temperatures. We found that reversible high-temperature structural transitions in DNA polymerases decrease the rates of binding of these enzymes to the templates. Furthermore, activation energies and pre-exponential factors of the Arrhenius equation suggest that the mechanism of electrostatic enhancement of diffusion-controlled association plays a minor role in binding of templates to DNA polymerases.

  17. Cooperation between Catalytic and DNA-binding Domains Enhances Thermostability and Supports DNA Synthesis at Higher Temperatures by Thermostable DNA Polymerases

    Science.gov (United States)

    Pavlov, Andrey R.; Pavlova, Nadejda V.; Kozyavkin, Sergei A.; Slesarev, Alexei I.

    2012-01-01

    We have previously introduced a general kinetic approach for comparative study of processivity, thermostability, and resistance to inhibitors of DNA polymerases (Pavlov et. al., (2002) Proc. Natl. Acad. Sci. USA 99, 13510–13515). The proposed method was successfully applied to characterize hybrid DNA polymerases created by fusing catalytic DNA polymerase domains with various non-specific DNA binding domains. Here we use the developed kinetic analysis to assess basic parameters of DNA elongation by DNA polymerases and to further study the interdomain interactions in both previously constructed and new chimeric DNA polymerases. We show that connecting Helix-hairpin-Helix (HhH) domains to catalytic polymerase domains can increase thermostability, not only of DNA polymerases from extremely thermophilic species, but also of the enzyme from a faculatative thermophilic bacterium Bacillus stearothermophilus. We also demonstrate that addition of TopoV HhH domains extends efficient DNA synthesis by chimerical polymerases up to 105°C by maintaining processivity of DNA synthesis at high temperatures. We also found that reversible high-temperature structural transitions in DNA polymerases decrease the rates of binding of these enzymes to the templates. Furthermore, activation energies and pre-exponential factors of the Arrhenius equation suggest that the mechanism of electrostatic enhancement of diffusion-controlled association plays a minor role in binding templates to DNA polymerases. PMID:22320201

  18. Low pressure EGR system having full range capability

    Science.gov (United States)

    Easley, Jr., William Lanier; Milam, David Michael; Roozenboom, Stephan Donald; Bond, Michael Steven; Kapic, Amir

    2009-09-22

    An exhaust treatment system for an engine is disclosed and may have an air induction circuit, an exhaust circuit, and an exhaust recirculation circuit. The air induction circuit may be configured to direct air into the engine. The exhaust circuit may be configured to direct exhaust from the engine and include a turbine driven by the exhaust, a particulate filter disposed in series with and downstream of the turbine, and a catalytic device disposed in series with and downstream of the particulate filter. The exhaust recirculation circuit may be configured to selectively redirect at least some of the exhaust from between the particulate filter and the catalytic device to the air induction circuit. The catalytic device is selected to create backpressure within the exhaust circuit sufficient to ensure that, under normal engine operating conditions above low idle, exhaust can flow into the air induction circuit without throttling of the air.

  19. Materials for low-temperature fuel cells

    CERN Document Server

    Ladewig, Bradley; Yan, Yushan; Lu, Max

    2014-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in Low-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in low-temperature fuel cells. A related book will cover key materials in high-temperature fuel cells. The two books form part

  20. [Oil degradation by basidiomycetes in soil and peat at low temperatures].

    Science.gov (United States)

    Kulikova, N A; Klein, O I; Pivchenko, D V; Landesman, E O; Pozdnyakova, N N; Turkovskaya, O V; Zaichik, B Ts; Ruzhitskii, A O; Koroleva, O V

    2016-01-01

    A total of 17 basidiomycete strains causing white rot and growing on oil-contaminated substrates have been screened. Three strains with high (Steccherinum murashkinskyi), average (Trametes maxima), and low (Pleurotus ostreatus) capacities for the colonization of oil-contaminated substrates have been selected. The potential for degrading crude oil hydrocarbons has been assessed with the use of fungi grown on nonsterile soil and peat at low temperatures. Candida sp. and Rhodococcus sp. commercial strains have been used as reference organisms with oil-degrading ability. All microorganisms introduced in oil-contaminated soil have proved to be ineffective, whereas the inoculation of peat with basidiomycetes and oil-degrading microorganisms accelerated the destruction of oil hydrocarbons. The greatest degradation potential of oil-aliphatic hydrocarbons has been found in S. murashlinskyi. T. maxima turned out to be the most successful in degrading aromatic hydrocarbons. It has been suggested that aboriginal microflora contributes importantly to the effectiveness of oil-destructing microorganisms. T. maxima and S. murashkinskyi strains are promising for further study as oil-oxidizing agents during bioremediation of oil-contaminated peat soil under conditions of low temperatures.