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.

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...

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.

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

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...

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.

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

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

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

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....

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.

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....

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

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.

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.)

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.)

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.

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.

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.

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.

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.

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.

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....

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

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).

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

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...

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.

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.

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.

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.

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.

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.

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

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

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...

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.

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.

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.

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

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.

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.

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.

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.

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)

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.

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

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....

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.

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)

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.

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.

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

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

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)

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

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.)

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…

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.

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.

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.

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.

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.

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.

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).

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.

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....

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.

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...

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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...

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...

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...

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.

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

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

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.

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.

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.

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....

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.

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

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 ...

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.

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.

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.

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...

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.

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

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.

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.

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.

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 |

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.

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.

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...

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.

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.

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...

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.)

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.

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.

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

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...

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.)

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.

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

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.

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

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.

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

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.

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

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.

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.

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.

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.

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.

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

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.

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.

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.)

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)

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...

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...

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

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%.

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

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.

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.

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.

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.

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

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.

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

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.

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.

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.

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)

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.

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.

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.

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.

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.

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)

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)

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.

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...

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

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.

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

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.

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)

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.

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.

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.

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).

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.

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.

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)

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

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

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.

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.

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.

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

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...

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

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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

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.

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

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

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.

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...

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.

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

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%.

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.

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

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.)

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.

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.

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%.

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...

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.

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.

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

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

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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.

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}.

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.

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.

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.

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.

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

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)

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.

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

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 extended ignition/extinction hysteresis of the CPO reactor was due to a shift from partial to total oxidation (and hence to higher exothermicity) with decreasing reactor inlet temperature. The influence of different operating conditions such as stoichiometry, dilution with H{sub 2}O and CO{sub 2}, inlet and surface temperatures, pressure, residence time, noble metal loading, catalyst support und geometry were quantified. Those studies were facilitated with additional computations in ideal, zero-dimensional reactor models. Synthesis gas has been produced with high selectivity. Despite the high exhaust gas dilution, the catalytic light-off occurred at temperatures well-within the range of compressor outlet temperatures. Vigorous burning was sustained at inlet temperatures at least 200 K lower than the light-off temperature, indicating an extended ignition/extinction hysteresis during CPO of methane. The surface reaction mechanism captured the CH{sub 4} and O{sub 2} consumption; however, a slight overprediction of the total over the partial oxidation route was evident. In the upstream sections of the reactor, total and partial oxidation occurred in parallel, with the latter growing to more importance as oxygen consumption increased. Farther downstream, H{sub 2}O-reforming and water-gas-shift reactions became important. Synthesis gas production appeared, therefore, to be controlled by both the direct and the indirect reaction pathways. The H{sub 2}O dilution provided additional O(s) and OH(s) surface radicals, which resulted in increased H{sub 2} selectivity and CH{sub 4} conversion and in decreased CO selectivity. With H{sub 2}O dilution, lower catalyst temperatures could be obtained, which was beneficial for an extended catalyst/reactor lifetime. CO{sub 2} dilution had no significant chemical impact (dry reforming) under the investigated conditions due to the presence of the significantly faster oxy- and steam-reforming reactions. The primary effect of different

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

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

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.

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.)

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

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.

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.

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)

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).

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)

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

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

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

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.

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.

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.

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...

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.

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.

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.

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

Influence of Pt nanoparticles modified by La and Ce oxides on catalytic dehydrocyclization of n-alkanes

Directory of Open Access Journals (Sweden)

A.H. Samia

2015-06-01

Full Text Available Catalytic reforming accounts for a large share of the world’s gasoline production, it is the most important source of aromatics for the petrochemical industry. In addition, reforming of hydrocarbon on the dual-function catalysts has been found to form fundamentally different products in hydrogen diluents. Typical catalysts employed for this reforming process are Pt/Al2O3 and Pt-M/Al2O3, M being the promoter. These solids are characterized by both acid and metal functions which catalyze dehydrocyclization, dehydrogenation, isomerization and cracking processes. In this regard, information about cerium and lanthanum, as promoters, is hardly revealed. The present work aims to study the performance of Pt/Al2O3 catalysts modified by lanthanum or cerium during the conversion of cyclohexane, n-hexane and n-heptane. Catalytic activities of the prepared catalysts were tested using a micro catalytic pulse technique. Physicochemical characterization of the solid catalysts such as, surface area (SBET, Fourier transform infrared (FTIR, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, hydrogen-temperature programed reduction (H2-TPR, hydrogen-temperature-programed desorption (H2-TPD, CO2-TPD, NH3-TPD, high resolution transmission electron microscopy (HRTEM and X-ray diffraction (XRD were depicted. Results indicated clearly that Pt/Al2O3 catalyst is selective toward dehydrogenation to benzene which could be explained as due to the decrease in the active acid sites and the comparative segregation of the alumina support especially at 3% load of CeO. The presence of La2O3 in the Pt/Al2O3 catalyst promotes aromatization of n-hexane and n-heptane, also the dehydrocyclization of n-hexane is more difficult than that of n-heptane. Thus, modification of the Pt/Al2O3 catalyst by La, resulted in a more active and selective reforming catalyst.

Effect of temperature for synthesizing single-walled carbon nanotubes by catalytic chemical vapor deposition over Mo-Co-MgO catalyst

International Nuclear Information System (INIS)

Niu Zhiqiang; Fang Yan

2008-01-01

The influence of temperature on synthesizing single-walled carbon nanotubes (SWCNTs) by catalytic chemical vapor deposition of methane over Mo-Co-MgO catalyst was studied by Transmission Electron Microscope (TEM) and Raman scattering. The Mo-Co-MgO bimetallic catalyst was prepared by decomposing the mixture of magnesium nitrate, ammonium molybdate, citric acid, and cobalt nitrate. The results show that Mo-Co-MgO bimetallic catalyst is effective to synthesize SWCNTs. By using Mo-Co-MgO bimetallic catalyst, generation of SWCNTs even at 940 K was demonstrated. The optimum temperature of synthesizing SWCNTs over Mo-Co-MgO bimetallic catalyst may be about 1123 K. At 1123 K, the diameters of SWCNTs are in the range of 0.75-1.65 nm. The content of SWCNTs is increased with the increase of temperature below 1123 K and the carbon yield rate is also increased with the increase of synthesis temperature. Therefore, the amount of SWCNTs increases with the increase of temperature below 1123 K. However, above 1123 K, the content of SWCNTs is decreased with the increase of temperature; therefore, it is not effective to increase the amount of SWCNTs through increasing synthesis temperature above 1123 K

Understanding the mechanism of catalytic fast pyrolysis by unveiling reactive intermediates in heterogeneous catalysis

Science.gov (United States)

Hemberger, Patrick; Custodis, Victoria B. F.; Bodi, Andras; Gerber, Thomas; van Bokhoven, Jeroen A.

2017-06-01

Catalytic fast pyrolysis is a promising way to convert lignin into fine chemicals and fuels, but current approaches lack selectivity and yield unsatisfactory conversion. Understanding the pyrolysis reaction mechanism at the molecular level may help to make this sustainable process more economic. Reactive intermediates are responsible for product branching and hold the key to unveiling these mechanisms, but are notoriously difficult to detect isomer-selectively. Here, we investigate the catalytic pyrolysis of guaiacol, a lignin model compound, using photoelectron photoion coincidence spectroscopy with synchrotron radiation, which allows for isomer-selective detection of reactive intermediates. In combination with ambient pressure pyrolysis, we identify fulvenone as the central reactive intermediate, generated by catalytic demethylation to catechol and subsequent dehydration. The fulvenone ketene is responsible for the phenol formation. This technique may open unique opportunities for isomer-resolved probing in catalysis, and holds the potential for achieving a mechanistic understanding of complex, real-life catalytic processes.

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.

Novel Metal Nanomaterials and Their Catalytic Applications

Directory of Open Access Journals (Sweden)

Jiaqing Wang

2015-09-01

Full Text Available In the rapidly developing areas of nanotechnology, nano-scale materials as heterogeneous catalysts in the synthesis of organic molecules have gotten more and more attention. In this review, we will summarize the synthesis of several new types of noble metal nanostructures (FePt@Cu nanowires, Pt@Fe2O3 nanowires and bimetallic Pt@Ir nanocomplexes; Pt-Au heterostructures, Au-Pt bimetallic nanocomplexes and Pt/Pd bimetallic nanodendrites; Au nanowires, CuO@Ag nanowires and a series of Pd nanocatalysts and their new catalytic applications in our group, to establish heterogeneous catalytic system in “green” environments. Further study shows that these materials have a higher catalytic activity and selectivity than previously reported nanocrystal catalysts in organic reactions, or show a superior electro-catalytic activity for the oxidation of methanol. The whole process might have a great impact to resolve the energy crisis and the environmental crisis that were caused by traditional chemical engineering. Furthermore, we hope that this article will provide a reference point for the noble metal nanomaterials’ development that leads to new opportunities in nanocatalysis.

Selective Oxidation of Glycerol to Glyceric Acid in Base-Free Aqueous Solution at Room Temperature Catalyzed by Platinum Supported on Carbon Activated with Potassium Hydroxide

KAUST Repository

Tan, Hua

2016-04-18

Pt supported on KOH-activated mesoporous carbon (K-AMC) was used to catalyze glycerol oxidation under base-free conditions at room temperature. To study the relationship between the carbon surface chemistry and the catalytic performance of the K-AMC-based Pt catalysts, different levels of surface oxygen functional groups (SOFGs) on the AMC supports were induced by thermal treatment at different temperatures under inert or H2 gas. A strong effect of the surface chemistry was observed on AMC-supported Pt catalysts for glycerol oxidation. The presence of carboxylic acid groups impedes the adsorption of glycerol, which leads to the reduction of catalytic activity, whereas the presence of high-desorption-temperature SOFGs, such as phenol, ether, and carbonyl/quinone groups, provide hydrophilicity to the carbon surface that improves the adsorption of glycerol molecules on Pt metal surface, which is beneficial for the catalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic Organometallic Reactions of Ammonia

Science.gov (United States)

Klinkenberg, Jessica L.

2012-01-01

Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

Catalytic oxidation of soot over alkaline niobates

International Nuclear Information System (INIS)

Pecchi, G.; Cabrera, B.; Buljan, A.; Delgado, E.J.; Gordon, A.L.; Jimenez, R.

2013-01-01

Highlights: ► No previous reported studies about alkaline niobates as catalysts for soot oxidation. ► NaNbO 3 and KNbO 3 perovskite-type oxides show lower activation energy than other lanthanoid perovskite-type oxides. ► The alkaline niobate does not show deactivation by metal loss. - Abstract: The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N 2 adsorption, XRD, O 2 -TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO 3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO 3 > NaNbO 3 > LiNbO 3 . The RbNbO 3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO 3 , despite the lower apparent activation energy of NaNbO 3 , stress the importance of the metal nature and suggests the hypothesis that K + ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.

Molecular Components of Catalytic Selectivity

Energy Technology Data Exchange (ETDEWEB)

Somorjai, Gabor A.; Park, Jeong Y.

2008-07-02

Selectivity, that is, to produce one molecule out of many other thermodynamically feasible product molecules, is the key concept to develop 'clean manufacturing' processes that do not produce byproducts (green chemistry). Small differences in potential energy barriers for elementary reaction steps control which reaction channel is more likely to yield the desired product molecule (selectivity), instead of the overall activation energy for the reaction that controls turnover rates (activity). Recent studies have demonstrated the atomic- or molecular-level tailoring of parameters such as the surface structures of active sites that give rise to nanoparticle size and shape dependence of turnover rates and reaction selectivities. Here, we highlight seven molecular components that influence reaction selectivities. These include: surface structure, adsorbate-induced restructuring, adsorbate mobility, reaction intermediates, surface composition, charge transport, and oxidation states for model metal single crystal and colloid nanoparticle catalysts. We show examples of their functioning and describe in-situ instruments that permit us to investigate their roles in surface reactions.

Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

Energy Technology Data Exchange (ETDEWEB)

Somorjai, G.A.

2009-09-14

The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

Removal of Selected Heavy Metals from Green Mussel via Catalytic Oxidation

International Nuclear Information System (INIS)

Faizuan Abdullah; Abdull Rahim Mohd Yusoff; Wan Azelee Wan Abu Bakar; Razali Ismail; Dwi Priya Hadiyanto

2014-01-01

Perna viridis or green mussel is a potentially an important aquaculture product along the South Coast of Peninsular Malaysia especially Johor Straits. As the coastal population increases at tremendous rate, there was significant effect of land use changes on marine communities especially green mussel, as the heavy metals input to the coastal area also increase because of anthropogenic activities. Heavy metals content in the green mussel exceeded the Malaysian Food Regulations (1985) and EU Food Regulations (EC No: 1881/ 2006). Sampling was done at Johor Straits from Danga to Pendas coastal area for green mussel samples. This research introduces a catalytic oxidative technique for demetallisation in green mussel using edible oxidants such as peracetic acid (PAA) enhanced with alumina beads supported CuO, Fe 2 O 3 , and ZnO catalysts. The lethal dose of LD 50 to rats of PAA is 1540 mg kg -1 was verified by National Institute of Safety and Health, United State of America. The best calcination temperature for the catalysts was at 1000 degree Celsius as shown in the X-Ray Diffraction (XRD), Nitrogen Adsorption (BET surface area) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The demetallisation process in green mussel was done successfully using only 100 mgL -1 PAA and catalyzed with Fe 2 O 3 / Al 2 O 3 for up to 90 % mercury (Hg) removal. Using PAA with only 1 hour of reaction time, at room temperature (30-35 degree Celsius), pH 5-6 and salinity of 25-28 ppt, 90 % lead (Pb) was removed from life mussel without catalyst. These findings have a great prospect for developing an efficient and practical method for post-harvesting heavy metals removal in green mussel. (author)

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

NOx formation and selective non-catalytic reduction (SNCR) in a fluidized bed combustor of biomass

International Nuclear Information System (INIS)

Mahmoudi, Shiva; Baeyens, Jan; Seville, Jonathan P.K.

2010-01-01

Caledonian Paper (CaPa) is a major paper mill, located in Ayr, Scotland. For its steam supply, it previously relied on the use of a Circulating Fluidized Bed Combustor (CFBC) of 58 MW th , burning coal, wood bark and wastewater treatment sludge. It currently uses a bubbling fluidized bed combustor (BFBC) of 102 MW th to generate steam at 99 bar, superheated to 465 o C. The boiler is followed by steam turbines and a 15 kg/s steam circuit into the mill. Whereas previously coal, wood bark and wastewater treatment sludge were used as fuel, currently only plantation wood (mainly spruce), demolition wood, wood bark and sludge are used. Since these biosolids contain nitrogen, fuel NO x is formed at the combustion temperature of 850-900 o C. NO x emissions (NO + NO 2 ) vary on average between 300 and 600 mg/Nm 3 (dry gas). The current emission standard is 350 mg/Nm 3 but will be reduced in the future to a maximum of 233 mg/Nm 3 for stand-alone biomass combustors of capacity between 50 and 300 MW th according to the EU LCP standards. NO x abatement is therefore necessary. In the present paper we firstly review the NO x formation mechanisms, proving that for applications of fluidized bed combustion, fuel NO x is the main consideration, and the contribution of thermal NO x to the emissions insignificant. We then assess the deNO x techniques presented in the literature, with an updated review and special focus upon the techniques that are applicable at CaPa. From these techniques, Selective Non-catalytic Reduction (SNCR) using ammonia or urea emerges as the most appropriate NO x abatement solution. Although SNCR deNO x is a selective reduction, the reactions of NO x reduction by NH 3 in the presence of oxygen, and the oxidation of NH 3 proceed competitively. Both reactions were therefore studied in a lab-scale reactor and the results were transformed into design equations starting from the respective reaction kinetics. An overall deNO x yield can then be predicted for any

Determination of organic bases in non-aqueous solvents by catalytic thermometric titration.

Science.gov (United States)

Vajgand, V J; Kiss, T A; Gaál, F F; Zsigrai, I J

1968-07-01

Catalytic thermometric titrations have been developed for bases (brucine, diethylaniline, potassium acetate and triethylamine) in acetic acid by continuous and discontinuous addition of the standard solution and automatic temperature recording. The determination of weak bases, e.g., antipyrine, unsuccessful in acetic acid by catalytic thermometric titration, has been achieved by using nitromethane or acetic anhydride as solvent. Catalytic thermometric titrations were also performed by coulometric generation of hydrogen ions for the determination of micro amounts of weak bases in a mixture of acetic anhyride and acetic acid.

Degradation of the ammonia wastewater in aqueous medium with ozone in combination with mesoporous TiO2 catalytic

Science.gov (United States)

Liu, Zhiwu; Qiu, Jianping; Zheng, Chaocan; Li, Liqing

2017-03-01

TiO2 mesoporous nanomaterials are now widely used in catalytic ozone technology. In this paper, the market P25 as precursor hydrothermal method to prepare TiO2 mesoporous materials, ozone catalyst material characterization by transmission electron microscopy, surface area analyzers, and X-ray diffraction technique and found that nanotubes, nanosheets, nanorods through characterization results, nano-particles of different morphology and anatase and rutile proportion of the ozone catalytic material can be controlled by the calcination temperature and the temperature of hot water to give, and with the hot water temperature and calcination temperature, the catalyst becomes small aperture size larger catalyst crystalline phase from anatase to rutile gradually shift. Catalytic materials have been prepared by the Joint ozone degradation of ammonia wastewater to evaluate mesoporous TiO2 nanomaterials ozone catalytic performance, the results showed that: ammonia wastewater removal efficiency of various catalytic materials relatively separate ozone and markets P25 effects are significantly improved, and TiO2 nanotubes cooperate with ozone degradation ammonia wastewater highest efficiency, in addition, rutile TiO2 catalysts, the more the better the performance of their ozone catalysis.

Effect of selective catalytic reduction (SCR) on fine particle emission from two coal-fired power plants in China

Science.gov (United States)

Li, Zhen; Jiang, Jingkun; Ma, Zizhen; Wang, Shuxiao; Duan, Lei

2015-11-01

Nitrogen oxides (NOx) emission abatement of coal-fired power plants (CFPPs) requires large-scaled installation of selective catalytic reduction (SCR), which would reduce secondary fine particulate matter (PM2.5) (by reducing nitrate aerosol) in the atmosphere. However, our field measurement of two CFPPs equipped with SCR indicates a significant increase of SO42- and NH4+ emission in primary PM2.5, due to catalytic enhancement of SO2 oxidation to SO3 and introducing of NH3 as reducing agent. The subsequent formation of (NH4)2SO4 or NH4HSO4 aerosol is commonly concentrated in sub-micrometer particulate matter (PM1) with a bimodal pattern. The measurement at the inlet of stack also showed doubled primary PM2.5 emission by SCR operation. This effect should therefore be considered when updating emission inventory of CFPPs. By rough estimation, the enhanced primary PM2.5 emission from CFPPs by SCR operation would offset 12% of the ambient PM2.5 concentration reduction in cities as the benefit of national NOx emission abatement, which should draw attention of policy-makers for air pollution control.

Catalytic hydrogen recombination for nuclear containments

International Nuclear Information System (INIS)

Koroll, G.W.; Lau, D.W.P.; Dewit, W.A.; Graham, W.R.C.

1994-01-01

Catalytic recombiners appear to be a credible option for hydrogen mitigation in nuclear containments. The passive operation, versatility and ease of back fitting are appealing for existing stations and new designs. Recently, a generation of wet-proofed catalyst materials have been developed at AECL which are highly specific to H 2 -O 2 , are active at ambient temperatures and are being evaluated for containment applications. Two types of catalytic recombiners were evaluated for hydrogen removal in containments based on the AECL catalyst. The first is a catalytic combustor for application in existing air streams such as provided by fans or ventilation systems. The second is an autocatalytic recombiner which uses the enthalpy of reaction to produce natural convective flow over the catalyst elements. Intermediate-scale results obtained in 6 m 3 and 10 m 3 spherical and cylindrical vessels are given to demonstrate self-starting limits, operating limits, removal capacity, scaling parameters, flow resistance, mixing behaviour in the vicinity of an operating recombiner and sensitivity to poisoning, fouling and radiation. (author). 13 refs., 10 figs

COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER; FINAL

International Nuclear Information System (INIS)

Phillip E. Savage

1999-01-01

Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, we examined the oxidation of phenol over a commercial catalyst and over bulk MnO(sub 2), bulk TiO(sub 2), and CuO supported on Al(sub 2) O(sub 3). We used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which we can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO(sub 2) yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that we could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, we performed experiments with bulk transition metal oxides. The bulk MnO(sub 2) and TiO(sub 2) catalysts enhance both the phenol disappearance and CO(sub 2) formation rates during SCWO. MnO(sub 2) does not affect the selectivity to CO(sub 2), or to the phenol dimers at a given phenol conversion. However, the selectivities to CO(sub 2) are increased and the selectivities to phenol dimers are decreased in the presence of TiO(sub 2) , which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of

Plasma-activated core-shell gold nanoparticle films with enhanced catalytic properties

Energy Technology Data Exchange (ETDEWEB)

Llorca, Jordi, E-mail: jordi.llorca@upc.edu; Casanovas, Albert; Dominguez, Montserrat; Casanova, Ignasi [Universitat Politecnica de Catalunya, Institut de Tecniques Energetiques (Spain); Angurell, Inmaculada; Seco, Miquel; Rossell, Oriol [Universitat de Barcelona, Departament de Quimica Inorganica (Spain)

2008-03-15

Catalytically active gold nanoparticle films have been prepared from core-shell nanoparticles by plasma-activation and characterized by high-resolution transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Methane can be selectively oxidized into formic acid with an O{sub 2}-H{sub 2} mixture in a catalytic wall reactor functionalized with plasma-activated gold nanoparticle films containing well-defined Au particles of about 3.5 nm in diameter. No catalytic activity was recorded over gold nanoparticle films prepared by thermal decomposition of core-shell nanoparticles due to particle agglomeration.

Plasma-activated core-shell gold nanoparticle films with enhanced catalytic properties

International Nuclear Information System (INIS)

Llorca, Jordi; Casanovas, Albert; Dominguez, Montserrat; Casanova, Ignasi; Angurell, Inmaculada; Seco, Miquel; Rossell, Oriol

2008-01-01

Catalytically active gold nanoparticle films have been prepared from core-shell nanoparticles by plasma-activation and characterized by high-resolution transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Methane can be selectively oxidized into formic acid with an O 2 -H 2 mixture in a catalytic wall reactor functionalized with plasma-activated gold nanoparticle films containing well-defined Au particles of about 3.5 nm in diameter. No catalytic activity was recorded over gold nanoparticle films prepared by thermal decomposition of core-shell nanoparticles due to particle agglomeration

Fuel rich and fuel lean catalytic combustion of the stabilized confined turbulent gaseous diffusion flames over noble metal disc burners

Directory of Open Access Journals (Sweden)

Amal S. Zakhary

2014-03-01

Full Text Available Catalytic combustion of stabilized confined turbulent gaseous diffusion flames using Pt/Al2O3 and Pd/Al2O3 disc burners situated in the combustion domain under both fuel-rich and fuel-lean conditions was experimentally studied. Commercial LPG fuel having an average composition of: 23% propane, 76% butane, and 1% pentane was used. The thermal structure of these catalytic flames developed over Pt/Al2O3 and Pd/Al2O3 burners were examined via measuring the mean temperature distribution in the radial direction at different axial locations along the flames. Under-fuel-rich condition the flames operated over Pt catalytic disc attained high temperature values in order to express the progress of combustion and were found to achieve higher activity as compared to the flames developed over Pd catalytic disc. These two types of catalytic flames demonstrated an increase in the reaction rate with the downstream axial distance and hence, an increase in the flame temperatures was associated with partial oxidation towards CO due to the lack of oxygen. However, under fuel-lean conditions the catalytic flame over Pd catalyst recorded comparatively higher temperatures within the flame core in the near region of the main reaction zone than over Pt disc burner. These two catalytic flames over Pt and Pd disc burners showed complete oxidation to CO2 since the catalytic surface is covered by more rich oxygen under the fuel-lean condition.

Catalytic properties of niobium compounds

International Nuclear Information System (INIS)

Tanabe, K.; Iizuka, T.

1983-04-01

The catalytic activity and selectivity of niobium compounds including oxides, salts, organometallic compounds and others are outlined. The application of these compounds as catalysts to diversified reactions is reported. The nature and action of niobium catalysts are characteristic and sometimes anomalous, suggesting the necessity of basic research and the potential use as catalysts for important processes in the chemical industry. (Author) [pt

Catalytic dehydration of ethanol using transition metal oxide catalysts.

Science.gov (United States)

Zaki, T

2005-04-15

The aim of this work is to study catalytic ethanol dehydration using different prepared catalysts, which include Fe(2)O(3), Mn(2)O(3), and calcined physical mixtures of both ferric and manganese oxides with alumina and/or silica gel. The physicochemical properties of these catalysts were investigated via X-ray powder diffraction (XRD), acidity measurement, and nitrogen adsorption-desorption at -196 degrees C. The catalytic activities of such catalysts were tested through conversion of ethanol at 200-500 degrees C using a catalytic flow system operated under atmospheric pressure. The results obtained indicated that the dehydration reaction on the catalyst relies on surface acidity, whereas the ethylene production selectivity depends on the catalyst chemical constituents.

Impact of selective catalytic reduction systems on the operation of coal and oil fired boilers and downstream equipment

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

The history of the development of selective catalytic reduction (SCR) technology has clearly demonstrated that whenever the technology arrives in a new region of the world new challenges are met. This paper discusses some of these historical challenges and their particular solutions in some detail. The paper shows that the design of successful SCR systems is extremely site-specific, but that the technology continues to evolve to meet these continuously changing demands. Most recently the increased power of CFD technology has enabled SCR to meet the more stringent North American emissions criteria through optimal fluid dynamic design. 4 figs.

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.

Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

Energy Technology Data Exchange (ETDEWEB)

Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei [South China Univ. of Technology, Guangzhou (China)

2014-06-15

High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H{sub 2}O{sub 2}) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS{sub 4})) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS{sub 4}). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS{sub 4})/H{sub 2}O{sub 2} was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS{sub 4})/H{sub 2}O{sub 2} system.

Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

International Nuclear Information System (INIS)

Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei

2014-01-01

High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H 2 O 2 ) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS 4 )) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS 4 ). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS 4 )/H 2 O 2 was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS 4 )/H 2 O 2 system

Comparative catalytic activity of PET track-etched membranes with embedded silver and gold nanotubes

Science.gov (United States)

Mashentseva, Anastassiya; Borgekov, Daryn; Kislitsin, Sergey; Zdorovets, Maxim; Migunova, Anastassiya

2015-12-01

Irradiated by heavy ions nanoporous polyethylene terephthalate track-etched membranes (PET TeMs) after +15Kr84 ions bombardment (1.75 MeV/nucl with the ion fluency of 1 × 109 cm-2) and sequential etching was applied in this research as a template for development of composites with catalytically enriched properties. A highly ordered silver and gold nanotubes arrays were embedded in 100 nm pores of PET TeMs via electroless deposition technique at 4 °C during 1 h. All "as-prepared" composites were examined for catalytic activity using reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride as a common reaction to test metallic nanostructures catalysts. The effect of temperature on the catalytic activity was investigated in range of 292-313 K and activation energy were calculated. Kapp of Ag/PET composites linearly increase with an increase of the temperature thus normal Arrhenius behavior have been seen and the activation energy was calculated to be 42.13 kJ/mol. Au/PET composites exhibit not only more powerful catalytic activity but also non-linear dependence of rate constant from temperature. Kapp increased with increasing temperature throughout the 292-308 K temperature range; the reaction had an activation energy 65.32 kJ/mol. In range 311-313 K rate constant dramatically decreased and the apparent activation energy at this temperature rang was -91.44 kJ/mol due some structural changes, i.e. agglomeration of Au nanoparticles on the surface of composite.

TEMPO functionalized C60 fullerene deposited on gold surface for catalytic oxidation of selected alcohols

International Nuclear Information System (INIS)

Piotrowski, Piotr; Pawłowska, Joanna; Sadło, Jarosław Grzegorz; Bilewicz, Renata; Kaim, Andrzej

2017-01-01

C 60 TEMPO 10 catalytic system linked to a microspherical gold support through a covalent S-Au bond was developed. The C 60 TEMPO 10 @Au composite catalyst had a particle size of 0.5–0.8 μm and was covered with the fullerenes derivative of 2.3 nm diameter bearing ten nitroxyl groups; the organic film showed up to 50 nm thickness. The catalytic composite allowed for the oxidation under mild conditions of various primary and secondary alcohols to the corresponding aldehyde and ketone analogues with efficiencies as high as 79–98%, thus giving values typical for homogeneous catalysis, while retaining at the same time all the advantages of heterogeneous catalysis, e.g., easy separation by filtration from the reaction mixture. The catalytic activity of the resulting system was studied by means of high pressure liquid chromatography. A redox mechanism was proposed for the process. In the catalytic cycle of the oxidation process, the TEMPO moiety was continuously regenerated in situ with an applied primary oxidant, for example, O 2 /Fe 3+ system. The new intermediate composite components and the final catalyst were characterized by various spectroscopic methods and thermogravimetry.

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.)

The catalytic activity of several tungsten oxides for the oxidation of propene

International Nuclear Information System (INIS)

De Rossi, S.; Schiavello, M.; Rome Univ.; Iguchi, E.; Tilley, R.J.D.

1976-01-01

A study has been made of the catalytic oxidation of propene over the oxides WO 3 , WOsub(2,95), WOsub(2,90), WOsub(2,72) and Wo 2 , which were selected because they possess specific features of chemical and structural interest rather than for their catalytic ability. It was found that the oxides WOsub(2,95), WOsub(2,90) and WOsub(2,72) all selectively produce acrolein in small amounts. The oxides WO 3 and WO 2 were non-selective and rather inactive. The results are discussed in terms of a mechanism involving both variable valence in the crystal and the specific structural geometry of these compounds. (orig.) [de

Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects

Directory of Open Access Journals (Sweden)

Valery E. Tarabanko

2017-11-01

Full Text Available 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.

The effect of sexual selection on adaptation and extinction under increasing temperatures.

Science.gov (United States)

Parrett, Jonathan M; Knell, Robert J

2018-04-25

Strong sexual selection has been reported to both enhance and hinder the adaptive capacity and persistence of populations when exposed to novel environments. Consequently, how sexual selection influences population adaption and persistence under stress remains widely debated. Here, we present two empirical investigations of the fitness consequences of sexual selection on populations of the Indian meal moth, Plodia interpunctella, exposed to stable or gradually increasing temperatures. When faced with increasing temperatures, strong sexual selection was associated with both increased fecundity and offspring survival compared with populations experiencing weak sexual selection, suggesting sexual selection acts to drive adaptive evolution by favouring beneficial alleles. Strong sexual selection did not, however, delay extinction when the temperature became excessively high. By manipulating individuals' mating opportunities during fitness assays, we were able to assess the effect of multiple mating independently from the effect of population-level sexual selection, and found that polyandry has a positive effect on both fecundity and offspring survival under increasing temperatures in those populations evolving with weak sexual selection. Within stable temperatures, there were some benefits from strong sexual selection but these were not consistent across the entire experiment, possibly reflecting changing costs and benefits of sexual selection under stabilizing and directional selection. These results indicate that sexual selection can provide a buffer against climate change and increase adaptation rates within a continuously changing environment. These positive effects of sexual selection may, however, be too small to protect populations and delay extinction when environmental changes are relatively rapid. © 2018 The Author(s).

The kinetics of chirality assignment in catalytic single-walled carbon nanotube growth and the routes towards selective growth.

Science.gov (United States)

Xu, Ziwei; Qiu, Lu; Ding, Feng

2018-03-21

Depending on its specific structure, or so-called chirality, a single-walled carbon nanotube (SWCNT) can be either a conductor or a semiconductor. This feature ensures great potential for building ∼1 nm sized electronics if chirality-selected SWCNTs could be achieved. However, due to the limited understanding of the growth mechanism of SWCNTs, reliable methods for chirality-selected SWCNTs are still pending. Here we present a theoretical model on the chirality assignment and control of SWCNTs during the catalytic growth. This study reveals that the chirality of a SWCNT is determined by the kinetic incorporation of pentagons, especially the last (6 th ) one, during the nucleation stage. Our analysis showed that the chirality of a SWCNT is randomly assigned on a liquid or liquid-like catalyst surface, and two routes of synthesizing chirality-selected SWCNTs, which are verified by recent experimental achievements, are demonstrated. They are (i) by using high melting point crystalline catalysts, such as Ta, W, Re, Os, or their alloys, and (ii) by frequently changing the chirality of SWCNTs during their growth. This study paves the way for achieving chirality-selective SWCNT growth for high performance SWCNT based electronics.

Investigation into catalytic properties of the second group metal molybdates in acrolein oxidation

International Nuclear Information System (INIS)

Yakubovich, M.N.; Gorochovatskij, Ya.B.; Alchazov, T.G.; Adzhamov, K.Yu.

1976-01-01

The catalytic properties are investigated of magnesium, calcium, strontium, zinc, cadmium, and barium molybdates. Temperature dependence of catalysts activity is studied. At temperature over 370 deg C the activity becomes higher in the series ZnMoO 4 -CaMoO 4 -MgMoO 4 -SrMoO 4 . A sharp fall in the activity is observed for BaMoO 4 , and CdMoO 4 . SrMoO 4 is the most active catalyst. The activity series have been made up with respect to the formation of acrylic acid: MgMoO 4 >ZnMoO 4 >CaMoO 4 , and also with respect to the formation of the deep oxidation products: SrMoO 4 >CaMoO 4 >MgMoO 4 >ZnMoO 4 . The dependence of selectivity with respect to the formation of acrylic acid and the sum of the acids on temperature is provided

Effect of Drying Temperature on Iron Fischer-Tropsch Catalysts Prepared by Solvent Deficient Precipitation

Directory of Open Access Journals (Sweden)

Michael K. Albretsen

2017-01-01

Full Text Available A novel solvent deficient precipitation (SDP method to produce nanoparticles was studied for its potential in Fischer-Tropsch synthesis (FTS catalysis. Using Fe(NO33·9H2O as the iron-containing precursor, this method produces ferrihydrite particles which are then dried, calcined, reduced, and carbidized to form the active catalytic phase for FTS. Six different drying profiles, including final drying temperatures ranging between 80 and 150°C, were used to investigate the effect of ammonium nitrate (AN, a major by-product of reaction between Fe(NO33·9H2O and NH4HCO3 in the SDP method. Since AN has two phase-transitions within this range of drying temperatures, three different AN phases can exist during the drying of the catalyst precursors. These AN phases, along with physical changes occurring during the phase transitions, may affect the pore structure and the agglomeration of ferrihydrite crystallites, suggesting possible reasons for the observed differences in catalytic performance. Catalysts dried at 130°C showed the highest FTS rate and the lowest methane selectivity. In general, better catalytic performance is related to the AN phase present during drying as follows: phase III > phase II > phase I. However, within each AN phase, lower drying temperatures led to better catalytic properties.

Catalytic Steam Reforming of Toluene as a Model Compound of Biomass Gasification Tar Using Ni-CeO2/SBA-15 Catalysts

Directory of Open Access Journals (Sweden)

Erik Dahlquist

2013-07-01

Full Text Available Nickel supported on SBA-15 doped with CeO2 catalysts (Ni-CeO2/SBA-15 was prepared, and used for steam reforming of toluene which was selected as a model compound of biomass gasification tar. A fixed-bed lab-scale set was designed and employed to evaluate the catalytic performances of the Ni-CeO2/SBA-15 catalysts. Experiments were performed to reveal the effects of several factors on the toluene conversion and product gas composition, including the reaction temperature, steam/carbon (S/C ratio, and CeO2 loading content. Moreover, the catalysts were subjected to analysis of their carbon contents after the steam reforming experiments, as well as to test the catalytic stability over a long experimental period. The results indicated that the Ni-CeO2/SBA-15 catalysts exhibited promising capabilities on the toluene conversion, anti-coke deposition and catalytic stability. The toluene conversion reached as high as 98.9% at steam reforming temperature of 850 °C and S/C ratio of 3 using the Ni-CeO2(3wt%/SBA-15 catalyst. Negligible coke formation was detected on the used catalyst. The gaseous products mainly consisted of H2 and CO, together with a little CO2 and CH4.

HIgh Temperature Photocatalysis over Semiconductors

Science.gov (United States)

Westrich, Thomas A.

Due in large part to in prevalence of solar energy, increasing demand of energy production (from all sources), and the uncertain future of petroleum energy feedstocks, solar energy harvesting and other photochemical systems will play a major role in the developing energy market. This dissertation focuses on a novel photochemical reaction process: high temperature photocatalysis (i.e., photocatalysis conducted above ambient temperatures, T ≥ 100°C). The overarching hypothesis of this process is that photo-generated charge carriers are able to constructively participate in thermo-catalytic chemical reactions, thereby increasing catalytic rates at one temperature, or maintaining catalytic rates at lower temperatures. The photocatalytic oxidation of carbon deposits in an operational hydrocarbon reformer is one envisioned application of high temperature photocatalysis. Carbon build-up during hydrocarbon reforming results in catalyst deactivation, in the worst cases, this was shown to happen in a period of minutes with a liquid hydrocarbon. In the presence of steam, oxygen, and above-ambient temperatures, carbonaceous deposits were photocatalytically oxidized over very long periods (t ≥ 24 hours). This initial experiment exemplified the necessity of a fundamental assessment of high temperature photocatalytic activity. Fundamental understanding of the mechanisms that affect photocatalytic activity as a function of temperatures was achieved using an ethylene photocatalytic oxidation probe reaction. Maximum ethylene photocatalytic oxidation rates were observed between 100 °C and 200 °C; the maximum photocatalytic rates were approximately a factor of 2 larger than photocatalytic rates at ambient temperatures. The loss of photocatalytic activity at temperatures above 200 °C is due to a non-radiative multi-phonon recombination mechanism. Further, it was shown that the fundamental rate of recombination (as a function of temperature) can be effectively modeled as a

Structural, catalytic and magnetic properties of Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Briceno, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Del Castillo, Hector [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Sagredo, V. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Bramer-Escamilla, Werner; Silva, Pedro [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of)

2012-12-15

Highlights: Black-Right-Pointing-Pointer Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} ferrite synthesized by sol-gel auto-combustion method. Black-Right-Pointing-Pointer Structural identification, magnetic and catalytic properties were investigated. Black-Right-Pointing-Pointer Characterization by TGA, DTA, XRD, SEM, TEM and VSM techniques. Black-Right-Pointing-Pointer Magnetic properties decrease with the increase of Cu{sup 2+} doping. Black-Right-Pointing-Pointer The selective conversion to N{sub 2} is higher for Cu-Co mixed ferrites. - Abstract: Copper substituted cobalt ferrite Cu{sub 1-X}Co{sub X}Fe{sub 2}O{sub 4} (0 {<=}x {<=} 1) have been synthesized using sol-gel auto combustion method with citric acid as fuel. Structural identification, magnetic and catalytic properties were investigated using thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and their application in the selective catalytic reduction of NOx were studied. Analysis of structural properties reveals that all samples have cubic spinel structure. Room temperature magnetic hysteresis measurements as a function of magnetic field infer that the magnetic properties decrease with Cu{sup 2+} doping which may be due to the difference of the magnetic moment of Cu{sup 2+} and Co{sup 2+} ions. The higher activity of the samples in NO selective reduction to N{sub 2} occurs at 350 Degree-Sign C, reaching a maximum of 38% NO conversion and 95% of selective conversion to N{sub 2}. The compositions containing both Cu{sup 2+} and Co{sup 2+} ions are more active to the products selectivity to N{sub 2}, suggesting a synergistic effect on the active surface of ferrite and the effect of Co{sup 2+} is more pronounced than Cu{sup 2+} towards NO conversion.

Influence of crystallite size and shape of zeolite ZSM-22 on its activity and selectivity in the catalytic cracking of n-octane

Energy Technology Data Exchange (ETDEWEB)

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

2013-11-01

Light olefins belong to the major building blocks for the petrochemical industry, particularly for the production of polymers. It has become necessary to increase the production of light olefins specifically in the case for propene with so called 'on-purpose propene' technologies. One possible route is to increase the amount of propene that can be obtained from Fluid Catalytic Cracking (FCC) by optimizing the catalyst through introducing new additives, which offer a high selectivity to propene. Zeolite ZSM-22 samples with different crystallite sizes and morphologies have been synthesized via hydrothermal syntheses and characterized by powder X-Ray diffraction, nitrogen physisorption, atomic absorption spectroscopy, scanning electron microscopy and solid-state NMR spectroscopy. The zeolites in the Broensted-acid form have been tested as catalysts in the catalytic cracking of n-octane as a model hydrocarbon. Clear influences of the crystallite size on the deactivation behavior have been observed. Larger crystals of zeolite ZSM-22 produce an increased amount of coke deposits resulting in a faster deactivation of the catalyst. The experimental results suggest that there is probably some influence of pore diffusion on the catalytic activity of the ZSM-22 sample with the large crystallite size. However a noticeable influence on the general product distribution could not be observed. (orig.)

Determination of the positions of aluminum atoms introduced into SSZ-35 and the catalytic properties of the generated Brønsted acid sites.

Science.gov (United States)

Miyaji, Akimitsu; Kimura, Nobuhiro; Shiga, Akinobu; Hayashi, Yoshihiro; Nishitoba, Toshiki; Motokura, Ken; Baba, Toshihide

2017-03-01

The positions of aluminum (Al) atoms in SSZ-35 together with the characteristics of the generated protons were investigated by 27 Al multiple quantum magic-angle spinning (MQ-MAS), 29 Si MAS, and 1 H MAS NMR data analyses accompanied by a variable temperature 1 H MAS NMR analysis. The origin of the acidic -OH groups (Brønsted acid sites) generated by introducing Al atoms into the T sites was investigated and the T sites introduced into the Al atoms were revealed. To further determine the catalytic properties of the acidic protons generated in SSZ-35, the influence of the concentration of the Al atoms on the catalytic activity and selectivity during the transformation of toluene was examined.

Preparation of H-mordenite/MCM-48 composite and its catalytic performance in the alkylation of toluene with tert-butanol

Science.gov (United States)

Zhou, Zhiwei; Cheng, Fuling; Qin, Juan; Yu, Pengcheng; Xu, Lin; Gu, Zhiqiang; Liu, Xiaoqin; Wu, Wenliang

2017-09-01

A series of HM/MCM-48 samples with different SiO2/Al2O3 molar ratio were prepared by sol-gel method. The prepared catalysts were characterized by XRD, N2 adsorption-desorption, NH3-TPD, FT-IR, SEM, and TEM techniques, and their catalytic performance was investigated in alkylation of toluene with tert-butanol. The adsorption capacity and the acid sites amount of HM/MCM-48-4 sample prepared by growing MCM-48 on the surface of HM zeolite are much higher than that of their mechanical mixture (HM/MCM-48(4) sample) due to its biporous structure; it shows higher catalytic performance than other HM/MCM-48 samples. The influence of reaction conditions on the catalytic performance of HM/MCM-48-4 zeolite was discussed. Toluene conversion of 41.4% and p-tert-butyltoluene selectivity of 73.5% were obtained at the weight ratio of toluene to HM/MCM-48-4 of 5, reaction temperature of 453 K, reaction time of 5 h and the molar ratio of toluene to tert-butanol of 0.5.

Selective Catalytic Synthesis Using the Combination of Carbon Dioxide and Hydrogen: Catalytic Chess at the Interface of Energy and Chemistry.

Science.gov (United States)

Klankermayer, Jürgen; Wesselbaum, Sebastian; Beydoun, Kassem; Leitner, Walter

2016-06-20

The present Review highlights the challenges and opportunities when using the combination CO2 /H2 as a C1 synthon in catalytic reactions and processes. The transformations are classified according to the reduction level and the bond-forming processes, covering the value chain from high volume basic chemicals to complex molecules, including biologically active substances. Whereas some of these concepts can facilitate the transition of the energy system by harvesting renewable energy into chemical products, others provide options to reduce the environmental impact of chemical production already in today's petrochemical-based industry. Interdisciplinary fundamental research from chemists and chemical engineers can make important contributions to sustainable development at the interface of the energetic and chemical value chain. The present Review invites the reader to enjoy this exciting area of "catalytic chess" and maybe even to start playing some games in her or his laboratory. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method to produce catalytically active nanocomposite coatings

Science.gov (United States)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2016-02-09

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

Method to produce catalytically active nanocomposite coatings

Energy Technology Data Exchange (ETDEWEB)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2017-12-19

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

Modelling and Simulation of Packed Bed Catalytic Converter for Oxidation of Soot in Diesel Powered Vehicles Flue Gas

Directory of Open Access Journals (Sweden)

Mohammad Nasikin

2010-10-01

Full Text Available Diesel vehicle is used in Indonesia in very big number. This vehicle exhausts pollutants especially diesel soot that can be reduces by using a catalytic converter to convert the soot to CO2. To obtain the optimal dimension of catalytic converter it is needed a model that can represent the profile of soot weight, temperature and pressure along the catalytic converter. In this study, a model is developed for packed bed catalytic converter in an adiabatic condition based on a kinetic study that has been  reported previously. Calculation of developed equations in this model uses Polymath 5.X solver with Range Kutta Method. The simulation result shows that temperature profile along catalytic converter increases with the decrease of soot weight,  while pressure profile decreases. The increase of soot weight in entering gas increases the needed converter length. On the other hand, the increase of catalyst diameter does not affect to soot weight along converter and temperature profile, but results a less pressure drop. For 2.500 c diesel engine, packed bed catalytic converter with ellipse's cross sectional of 14,5X7,5 cm diagonal and 0,8 cm catalyst particle diameter, needs 4,1 cm length.

Effects of Mn- and K-addition on catalytic activity of calcium oxide for methane activation

International Nuclear Information System (INIS)

Park, Jong Sik; Kong, Jang Il; Lee, Sung Han; Jun, Jong Ho

1998-01-01

Pure CaO, Mn-doped CaO, Mn/CaO, and K/CaO catalysts were prepared and tested as catalysts for the oxidative coupling of methane in the temperature range of 600 to 800 .deg. C to investigate the effects of Mn- and K-addition on the catalytic activity of calcium oxide. To characterize the catalysts, X-ray powder diffraction (XRD), XPS, SEM, DSC, and TG analyses were performed. The catalytic reaction was carried out in a single-pass flow reactor using on-line gas chromatography system. Normalized reaction conditions were generally p(CH 4 )/p(O 2 )=250 Torr/50 Torr, total feed flow rate=30 mL/min, and 1 atm of total pressure with He being used as diluent gas. Among the catalysts tested, 6.3 mol% Mn-doped CaO catalyst showed the best C 2 yield of 8.0% with a selectivity of 43.2% at 775 .deg. C. The C 2 selectivity increased on lightly doped CaO catalysts, while decreased on heavily doped CaO((Mn)>6.3 mol%)catalysts. 6 wt.% Mn/CaO and 6 wt.% K/CaO catalysts showed the C 2 selectivities of 13.2% and 30.9%, respectively, for the reaction. Electrical conductivities of CaO and Mn-doped CaO were measured in the temperature range of 500 to 1000 .deg. C at Po2's of 10 -3 to 10 -1 atm. The electrical conductivity was decreased with Mn-doping and increased with increasing Po 2 in the range of 10 -3 to 10 -1 atm, indicating the specimens to be p-type semiconductors. It was suggested that the interstitial oxygen ions formed near the surface can activate methane and the formation of interstitial oxygen ions was discussed on the basis of solid-state chemistry

One-pot synthesis of Cu/ZnO/ZnAl2O4 catalysts and their catalytic performance in glycerol hydrogenolysis

KAUST Repository

Tan, Hua

2013-01-01

In this work, a series of Cu/ZnO/ZnAl2O4 catalysts with different metal molar fractions (Cu:Zn:Al) were successfully prepared using a one-pot method via the evaporation-induced self-assembly (EISA) of Pluronic P123 and the corresponding metal precursors. The catalysts were characterized using N2 adsorption, H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). The catalytic properties of the resulting Cu/ZnO/ZnAl2O4 with different molar fractions of metals were investigated for the selective hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). It was observed that the ZnAl2O 4 support exerts a strong positive effect on the catalytic activity of the copper-based catalysts, and the presence of ZnO further improves the catalytic activity of the Cu/ZnAl2O4 catalysts. The Cu/ZnO/ZnAl2O4 catalyst (Cu10Zn 30Al60, Cu/Zn/Al molar ratio is 10:30:60), which was the best catalyst, exhibited the highest yield (79%) of 1,2-PDO with 85.8% glycerol conversion and 92.1% 1,2-PDO selectivity at 180 °C reaction temperature in 80 wt% glycerol aqueous solution over 10 h reaction time. The high catalytic activity was attributed to the presence of the ZnAl2O4 support, the strong interaction between ZnO and Cu nanoparticles and the small particle size of ZnO and Cu. Moreover, the Cu/ZnO/ZnAl2O4 catalysts exhibited higher stability than Cu/ZnO and Cu/ZnO/Al2O 3 catalysts prepared by a co-precipitation method during consecutive cycling experiments, which is due to the high chemical and thermal stability of crystalline ZnAl2O4 under harsh reaction conditions. This journal is © The Royal Society of Chemistry.

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.

Direct Hysteresis Heating of Catalytically Active Ni–Co Nanoparticles as Steam Reforming Catalyst

DEFF Research Database (Denmark)

Mortensen, Peter Mølgaard; Engbæk, Jakob Soland; Vendelbo, Søren Bastholm

2017-01-01

We demonstrated a proof-of-concept catalytic steam reforming flow reactor system heated only by supported magnetic nickel–cobalt nanoparticles in an oscillating magnetic field. The heat transfer was facilitated by the hysteresis heating in the nickel–cobalt nanoparticles alone. This produced...... a sufficient power input to equilibrate the reaction at above 780 °C with more than 98% conversion of methane. The high conversion of methane indicated that Co-rich nanoparticles with a high Curie temperature provide sufficient heat to enable the endothermic reaction, with the catalytic activity facilitated...... by the Ni content in the nanoparticles. The magnetic hysteresis losses obtained from temperature-dependent hysteresis measurements were found to correlate well with the heat generation in the system. The direct heating of the catalytic system provides a fast heat transfer and thereby overcomes the heat...

Catalytic Oxidation of Cyanogen Chloride over a Monolithic Oxidation Catalyst

National Research Council Canada - National Science Library

Campbell, Jeffrey

1997-01-01

The catalytic oxidation of cyanogen chloride was evaluated over a monolithic oxidation catalyst at temperatures between 200 and 300 deg C in air employing feed concentrations between 100 and 10,000 ppm...

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.

Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

Directory of Open Access Journals (Sweden)

Zeeshan Nawaz

2009-12-01

Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

Selective Hydrogenation of Furfural to Furfuryl Alcohol in the Presence of a Recyclable Cobalt/SBA-15 Catalyst.

Science.gov (United States)

Audemar, Maïté; Ciotonea, Carmen; De Oliveira Vigier, Karine; Royer, Sébastien; Ungureanu, Adrian; Dragoi, Brindusa; Dumitriu, Emil; Jérôme, François

2015-06-08

The hydrogenation of furfural to furfuryl alcohol was performed in the presence of a Co/SBA-15 catalyst. High selectivity (96 %) at a conversion higher than 95 % is reported over this catalytic system. As the conversion of furfural to furfuryl alcohol occurs over metallic Co sites, the effect of reduction temperature, H2 pressure, and reaction temperature were studied. Optimum reaction conditions were: 150 °C, 1.5 h, 2.0 MPa of H2 . The catalyst was recyclable, and furfuryl alcohol was recovered with a purity higher than 90 %. The effect of the solvent concentration was also studied. With a minimum of 50 wt % of solvent, the selectivity to furfuryl alcohol and the conversion of furfural remained high (both over 80 %). Likewise, the activity of the catalyst is maintained even in pure furfural, which confirms the real potential of the proposed catalytic system. This catalyst was also used in the hydrogenation of levulinic acid to produce γ-valerolactone selectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Directional synthesis of ethylbenzene through catalytic transformation of lignin.

Science.gov (United States)

Fan, Minghui; Jiang, Peiwen; Bi, Peiyan; Deng, Shumei; Yan, Lifeng; Zhai, Qi; Wang, Tiejun; Li, Quanxin

2013-09-01

Transformation of lignin to ethylbenzene can provide an important bulk raw material for the petrochemical industry. This work explored the production of ethylbenzene from lignin through the directional catalytic depolymerization of lignin into the aromatic monomers followed by the selective alkylation of the aromatic monomers. For the first step, the aromatics selectivity of benzene derived from the catalytic depolymerization of lignin reached about 90.2 C-mol% over the composite catalyst of Re-Y/HZSM-5 (25). For the alkylation of the aromatic monomers in the second step, the highest selectivity of ethylbenzene was about 72.3 C-mol% over the HZSM-5 (25) catalyst. The reaction pathway for the transformation of lignin to ethylbenzene was also addressed. Present transformation potentially provides a useful approach for the production of the basic petrochemical material and development of high-end chemicals utilizing lignin as the abundant natural aromatic resource. Copyright © 2013 Elsevier Ltd. All rights reserved.

Temperature effects on kinetic parameters and substrate affinity of Cel7A cellobiohydrolases

DEFF Research Database (Denmark)

Sørensen, Trine Holst; Cruys-Bagger, Nicolaj; Windahl, Michael Skovbo

2015-01-01

Hypocrea jecorina and thermophilic Rasamsonia emersonii and two variants of these enzymes designed to elucidate the role of the carbohydrate binding module (CBM). We consistently found that the maximal rate increased strongly with temperature, whereas the affinity for the insoluble substrate decreased...... for affinity it slows down the catalytic process. Cel7A from the thermophilic organism was moderately more activated by temperature than the mesophilic analog. This is in accord with general theories on enzyme temperature adaptation and possibly relevant information for the selection of technical cellulases....

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.

Fundamental study of manganese dioxide for catalytic recombustion of exhaust gas of motor car

Energy Technology Data Exchange (ETDEWEB)

Shimoyamada, T

1974-01-01

The catalytic activities of five manganese dioxide preparations were tested in a pulse reactor to assess their carbon monoxide-oxidizing capability in relation to the catalytic afterburning of automobile exhaust gases. Catalysts prepared from manganese sulfate showed diminished catalytic activity as a result of sulfate poisoning. Higher oxidation activity was obtained with a catalyst prepared by precipitating the permanganate salt in acidic solution. Two forms of carbon monoxide adsorption were demonstrated, each with a characteristic activation energy and reaction temperature.

μ-reactor measurements of catalytic activity of mass selected nano-particles

DEFF Research Database (Denmark)

Riedel, Jakob Nordheim

The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ-reactors ......The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ......-reactors in combination with surface science techniques and computer simulations. The first project described is a study of hydrogen dissociation on mono-disperse platinum clusters. The second project studies methanation from carbon monoxide and hydrogen on nano-particles of nickel-iron alloys. The second study is a work...... in progress, and the corresponding chapter aims to summarise the results so far. Other projects are not included in the thesis because they are inconclusive or dead ends. Hydrogen dissociation was studied by the H2/D2 exchange reaction on SiO2-supported mono-disperse platinum clusters in a -reactor...

Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion.

Science.gov (United States)

Xu, Boran; Hartigan, Elizabeth M; Feula, Giancarlo; Huang, Zheng; Lumb, Jean-Philip; Arndtsen, Bruce A

2016-12-19

We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Xe/Kr Selectivity Measurements using AgZ-PAN at Various Temperatures

International Nuclear Information System (INIS)

Garn, Troy Gerry; Greenhalgh, Mitchell Randy; Watson, Tony Leroy

2015-01-01

In preparation for planned FY-15 Xe/Kr multi-column testing, a series of experiments were performed to determine the selectivity of Xe over Kr using the silver converted mordenite-polyacrylonitrile (AgZ-PAN) sorbent. Results from these experiments will be used for parameter selection guidelines to define test conditions for Kr gas capture purity evaluations later this year. The currently configured experimental test bed was modified by installing a new cooling apparatus to permit future multi-column testing with independent column temperature control. The modified test bed will allow for multi-column testing to facilitate a Xe separation followed by a Kr separation using engineered form sorbents. Selectivity experiments were run at temperatures of 295, 250 and 220 K. Two feed gas compositions of 1000 ppmv Xe, 150 ppmv Kr in either a He or an air balance were used. AgZ-PAN sorbent selectivity was calculated using Xe and Kr capacity determinations. AgZ-PAN sorbent selectivities for Xe over Kr of 72 were calculated at room temperature (295 K) using the feed gas with a He balance and 34 using the feed gas with an air balance. As the test temperatures were decreased the selectivity of Xe over Kr also decreased due to an increase in both Xe and Kr capacities. At 220 K, the sorbent selectivities for Xe over Kr were 22 using the feed gas with a He balance and 28 using the feed gas with an air balance. The selectivity results indicate that AgZ-PAN used in the first column of a multi-column configuration will provide adequate partitioning of Xe from Kr in the tested temperature range to produce a more pure Kr end product for collection.

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.

Liquid-phase chemical hydrogen storage: catalytic hydrogen generation under ambient conditions.

Science.gov (United States)

Jiang, Hai-Long; Singh, Sanjay Kumar; Yan, Jun-Min; Zhang, Xin-Bo; Xu, Qiang

2010-05-25

There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

Catalytic Fast Pyrolysis: A Review

Directory of Open Access Journals (Sweden)

Theodore Dickerson

2013-01-01

Full Text Available Catalytic pyrolysis is a promising thermochemical conversion route for lignocellulosic biomass that produces chemicals and fuels compatible with current, petrochemical infrastructure. Catalytic modifications to pyrolysis bio-oils are geared towards the elimination and substitution of oxygen and oxygen-containing functionalities in addition to increasing the hydrogen to carbon ratio of the final products. Recent progress has focused on both hydrodeoxygenation and hydrogenation of bio-oil using a variety of metal catalysts and the production of aromatics from bio-oil using cracking zeolites. Research is currently focused on developing multi-functional catalysts used in situ that benefit from the advantages of both hydrodeoxygenation and zeolite cracking. Development of robust, highly selective catalysts will help achieve the goal of producing drop-in fuels and petrochemical commodities from wood and other lignocellulosic biomass streams. The current paper will examine these developments by means of a review of existing literature.

Temperature-controlled two new Co(II) compounds with distinct topological networks: Syntheses, crystal structures and catalytic properties

Science.gov (United States)

Meng, Qing-Hua; Long, Xu; Liu, Jing-Li; Zhang, Shuan; Zhang, Guang-Hui

2018-04-01

Two new Co(II) coordination compounds, namely [Co2(bptc)(bpp)2]n (1) and [Co(bptc)0.5(bpp)]n (2) (H4bptc = biphenyl-3,3‧,5,5‧-tetracarboxylic acid, bpp = 1,3-di(4-pyridyl)propane), have been hydrothermally synthesized from the same reactants via tuning the reaction temperature. Single crystal X-ray diffraction analyses revealed that both 1 and 2 feature 2D sheet motifs. Topological analyses revealed that compounds 1 and 2 show distinct topological networks. Under the weak Van der Waals interactions, the 2D sheet motifs of compounds 1 and 2 are further packed into 2D→3D interdigitated supramolecular frameworks. Moreover, the two Co(II) compounds show high catalytic activities for degradation of methyl orange (MO) in a Fenten-like process.

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.

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

International Nuclear Information System (INIS)

Hayes, R.E.; Wanke, S.E.

2008-01-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

Energy Technology Data Exchange (ETDEWEB)

Hayes, R.E.; Wanke, S.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

2008-07-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs.

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)

Visualizing the mobility of silver during catalytic soot oxidation

DEFF Research Database (Denmark)

Gardini, Diego; Christensen, Jakob M.; Damsgaard, Christian Danvad

2016-01-01

The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation...

Synergy Effects of the Mixture of Bismuth Molybdate Catalysts with SnO2/ZrO2/MgO in Selective Propene Oxidation and the Connection between Conductivity and Catalytic Activity

DEFF Research Database (Denmark)

Le, Minh Thang; Do, Van Hung; Truong, Duc Duc

2016-01-01

Bismuth molybdate catalysts have been used for partial oxidation and ammoxidation of light hydrocarbons since the 1950s. In particular, there is the synergy effect (the enhancement of the catalytic activity in the catalysts mixed from different components) in different phases of bismuth molybdate...... catalysts which has been observed and studied since the 1980s; however, despite it being interpreted differently by different research groups, there is still no decisive conclusion on the origin of the synergy effect that has been obtained. The starting idea of this work is to find an answer......, impregnation, and sol-gel methods. The mixtures were characterized by XRD, BET, XPS, and EDX techniques to determine the phase composition and surface properties. The conductivities of these samples were recorded at the catalytic reaction temperature (300-450 degrees C). Comparison of the catalytic activities...

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

Directory of Open Access Journals (Sweden)

Mohamed E. Assal

2017-01-01

Full Text Available Zinc oxide nanoparticles doped manganese carbonate catalysts [X% ZnOx–MnCO3] (where X = 0–7 were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [X% ZnOx–MnO2] and [X% ZnOx–Mn2O3]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnOx–MnCO3 calcined at 300°C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnOx–MnCO3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol·g−1·h−1 and 390.6 turnover frequency (TOF. The specific activity obtained is the highest so far (to the best of our knowledge compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnOx nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.

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.

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

Catalytic behaviors of ruthenium dioxide films deposited on ferroelectrics substrates, by spin coating process

International Nuclear Information System (INIS)

Khachane, M.; Nowakowski, P.; Villain, S.; Gavarri, J.R.; Muller, Ch.; Elaatmani, M.; Outzourhite, A.; Luk'yanchuk, I.; Zegzouti, A.; Daoud, M.

2007-01-01

Catalytic ruthenium dioxide films were deposited by spin-coating process on ferroelectric films mainly constituted of SrBi 2 Ta 2 O 9 (SBT) and Ba 2 NaNb 5 O 15 (BNN) phases. After thermal treatment under air, these ferroelectric-catalytic systems were characterized by X-ray diffraction and scanning electron microscopy (SEM). SEM images showed that RuO 2 film morphology depended on substrate nature. A study of CH 4 conversion into CO 2 and H 2 O was carried out using these catalytic-ferroelectric multilayers: the conversion was analyzed from Fourier transform infrared (FTIR) spectroscopy, at various temperatures. Improved catalytic properties were observed for RuO 2 films deposited on BNN oxide layer

Optimization of catalytic glycerol steam reforming to light olefins using Cu/ZSM-5 catalyst

International Nuclear Information System (INIS)

Zakaria, Z.Y.; Amin, N.A.S.; Linnekoski, J.

2014-01-01

Highlights: • Glycerol steam reforming to light olefin using Cu/ZSM-5 process was optimized. • Response surface methodology and multi-objective genetic algorithm were employed. • Second order polynomial model produced adequately fitted experimental data. • Thermodynamic study inferred high temperature requirement for ethylene formation. • Turn-over-frequency at optimized responses is higher than the non-optimized process. - Abstract: Response surface methodology (RSM) and multi-objective genetic algorithm was employed to optimize the process parameters for catalytic conversion of glycerol, a byproduct from biodiesel production, to light olefins using Cu/ZSM-5 catalyst. The effects of operating temperature, weight hourly space velocity (WHSV) and glycerol concentration on light olefins selectivity and yield were observed. Experimental results revealed the data adequately fitted into a second-order polynomial model. The linear temperature and quadratic WHSV terms gave significant effect on both responses. Optimization of both the responses indicated that temperature favouring high light olefin formation lied beyond the experimental design range. The trend in the temperature profile concurred commensurately with the thermodynamic analysis. Multi-objective genetic algorithm was performed to attain a single set of processing parameters that could produce both the highest light olefin selectivity and yield. The turn-over-frequency (TOF) of the optimized responses demonstrated a slightly higher value than the one which was not optimized. Combination of RSM, multi-objective response and thermodynamic is useful to determine the process optimal operating conditions for industrial applications

Catalytic decomposition of nitrous oxide from nitric acid production tail gases. Investigation of inhibition effects. Executive summary

International Nuclear Information System (INIS)

Mul, G.; Perez-Ramirez, J.; Xu, Xiaoding; Oonk, H.; Yakovlev, A.

2001-06-01

Nitric acid production is an important source of nitrous oxide, one of the green-house gases. Catalytic decomposition of N2O in nitric acid tail-gases might be a possibility for emission reduction, but technology is not yet available. As a part of development of suitable catalytic systems, research was performed, aiming at: gaining an improved understanding of catalytic decomposition of N2O and the inhibiting effects of NO, NO2, H2O and O2; and preparing a 'go-no go' decision whether or not to proceed with subsequent re-search and development and if yes, to indicate what technology further development should aim for. Due to the presence of NOx and water in the nitric acid tail gases, catalytic decomposition proves not to be feasible at temperatures below 350C. At higher temperatures possibilities do exist and a number of promising catalysts are identified. These are active (80 - 100 % conversion) in the temperature range of 400 - 500C and under simulated tail gas conditions. Considering process conditions only (temperatures and composition of the tail-gases), the catalysts studied (pref. the Rh/Al2O3 types) could be in principle applied successfully in all Dutch nitric acid plants

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.

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...

TEMPO functionalized C{sub 60} fullerene deposited on gold surface for catalytic oxidation of selected alcohols

Energy Technology Data Exchange (ETDEWEB)

Piotrowski, Piotr; Pawłowska, Joanna [University of Warsaw, Department of Chemistry (Poland); Sadło, Jarosław Grzegorz [Institute of Nuclear Chemistry and Technology (Poland); Bilewicz, Renata; Kaim, Andrzej, E-mail: akaim@chem.uw.edu.pl [University of Warsaw, Department of Chemistry (Poland)

2017-05-15

C{sub 60}TEMPO{sub 10} catalytic system linked to a microspherical gold support through a covalent S-Au bond was developed. The C{sub 60}TEMPO{sub 10}@Au composite catalyst had a particle size of 0.5–0.8 μm and was covered with the fullerenes derivative of 2.3 nm diameter bearing ten nitroxyl groups; the organic film showed up to 50 nm thickness. The catalytic composite allowed for the oxidation under mild conditions of various primary and secondary alcohols to the corresponding aldehyde and ketone analogues with efficiencies as high as 79–98%, thus giving values typical for homogeneous catalysis, while retaining at the same time all the advantages of heterogeneous catalysis, e.g., easy separation by filtration from the reaction mixture. The catalytic activity of the resulting system was studied by means of high pressure liquid chromatography. A redox mechanism was proposed for the process. In the catalytic cycle of the oxidation process, the TEMPO moiety was continuously regenerated in situ with an applied primary oxidant, for example, O{sub 2}/Fe{sup 3+} system. The new intermediate composite components and the final catalyst were characterized by various spectroscopic methods and thermogravimetry.

Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil to Liquid Fuels

Directory of Open Access Journals (Sweden)

Wara Dyah Pita Rengga

2015-03-01

Full Text Available Reaction kinetics of catalytic cracking of rubber seed oil to liquid fuels has been investigated. The reac-tion was performed with sulfuric acid as catalyst at temperatures of 350-450 oC and the ratio of oil-catalyst of 0-2 wt.% for 30-90 minutes. Kinetics was studied using the model of 6-lump parameters. The parameters were rubber seed oil, gasoline, kerosene, diesel, gas, and coke. Analysis of experimen-tal data using regression models to obtain reaction rate constants. Activation energies and pre-exponential factors were then calculated based on the Arrhenius equation. The simulation result illus-trated that the six-lump kinetic model can well predict the product yields of rubber seed oil catalytic cracking. The product has high selectivity for gasoline fraction as liquid fuel and the smallest amount of coke. The constant indicates that secondary reactions occurred in diesel products compared to gaso-line and kerosene. The predicted results indicate that catalytic cracking of rubber seed oil had better be conducted at 450 oC for 90 minutes using 0.5 wt.% catalyst. © 2015 BCREC UNDIP. All rights reservedReceived: 3rd December 2013; Revised: 5th December 2014; Accepted: 7th December 2014How to Cite: Rengga, W.D.P., Handayani, P.A., Kadarwati, S., Feinnudin, A.(2015. Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil  to Liquid Fuels. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 50-60. (doi:10.9767/bcrec.10.1.5852.50-60Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.5852.50-60

Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

Science.gov (United States)

Sundararaman, Ramanathan

Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

Catalytic fast pyrolysis of biomass impregnated with potassium phosphate in a hydrogen atmosphere for the production of phenol and activated carbon

Science.gov (United States)

Lu, Qiang; Zhang, Zhen-xi; Wang, Xin; Guo, Hao-qiang; Cui, Min-shu; Yang, Yong-ping

2018-02-01

A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K3PO4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content. In addition, the pyrolytic solid residues were activated to prepare ACs with high specific surface areas. The results indicated that phenol could be obtained due to the synergistic effects of K3PO4 and hydrogen atmosphere, with the yield and selectivity reaching 5.3 wt% and 17.8% from catalytic fast pyrolysis of poplar wood with 8 wt% K3PO4 at 550 oC in a hydrogen atmosphere. This technique was adaptable to different woody materials for phenol production. Moreover, gas product generated from the pyrolysis process was feasible to be recycled to provide the hydrogen atmosphere, instead of extra hydrogen supply. In addition, the pyrolytic solid residue was suitable for AC preparation, using CO2 activation method, the specific surface area was as high as 1605 m2/g.

Catalytic destruction of tar in biomass derived producer gas

International Nuclear Information System (INIS)

Zhang Ruiqin; Brown, Robert C.; Suby, Andrew; Cummer, Keith

2004-01-01

The purpose of this study is to investigate catalytic destruction of tar formed during gasification of biomass, with the goal of improving the quality of the producer gas. This work focuses on nickel based catalysts treated with alkali in an effort to promote steam gasification of the coke that deposits on catalyst surfaces. A tar conversion system consisting of a guard bed and catalytic reactor was designed to treat the producer gas from an air blown, fluidized bed biomass gasifier. The guard bed used dolomite to crack the heavy tars. The catalytic reactor was used to evaluate three commercial steam reforming catalysts. These were the ICI46-1 catalyst from Imperial Chemical Industry and Z409 and RZ409 catalysts from Qilu Petrochemical Corp. in China. A 0.5-3 l/min slipstream from a 5 tpd biomass gasifier was used to test the tar conversion system. Gas and tar were sampled before and after the tar conversion system to evaluate the effectiveness of the system. Changes in gas composition as functions of catalytic bed temperature, space velocity and steam/TOC (total organic carbon) ratio are presented. Structural changes in the catalysts during the tests are also described

Catalytic copyrolysis of particle board and polypropylene over Al-MCM-48

Energy Technology Data Exchange (ETDEWEB)

Kim, Hannah; Choi, Suek Ju [School of Environmental Engineering, University of Seoul, Seoul 02504 (Korea, Republic of); Kim, Ji Man [Department of Chemistry, Sungkyunkwan University, Suwon 16419 (Korea, Republic of); Jeon, Jong-Ki [Department of Chemical Engineering, Kongju National University, Cheonan 31080 (Korea, Republic of); Park, Sung Hoon; Jung, Sang-Chul [Department of Environmental Engineering, Sunchon National University, Suncheon 57922 (Korea, Republic of); Kim, Sang Chai [Department of Environmental Education, Mokpo National University, Muan 58554 (Korea, Republic of); Park, Young-Kwon, E-mail: catalica@uos.ac.kr [School of Environmental Engineering, University of Seoul, Seoul 02504 (Korea, Republic of)

2016-10-15

Highlights: • Al-MCM-48 was used for catalytic copyrolysis of particle board and polypropylene. • Catalytic produced mainly hydrocarbons. • The hydrocarbons produced were mainly in the diesel range. - Abstract: Particle board and polypropylene (PP) at a mixing ratio of 1:1 were copyrolyzed over two Al-MCM-48 catalysts with Si/Al ratios of 20 and 80. The catalyst characteristics were examined by measuring the Brunauer-Emmett-Teller surface area, temperature programmed desorption of ammonia, and X-ray diffraction. The main pyrolysis products of particle board were oxygenates, acids, and phenolics, whereas a large quantity of hydrocarbons within the diesel fuel range was produced from copyrolysis with polypropylene. The catalytic copyrolysis of particle board and PP over the Al-MCM-48 catalysts produced bio-oil with a much larger hydrocarbon content than that from the catalytic pyrolysis of particle board only. The hydrocarbons produced were mainly in the diesel range, highlighting the potential for the production of high-quality fuel.

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

Development of a choronocoulometric method for determining traces of uranium using the catalytic nitrate reduction

International Nuclear Information System (INIS)

Cantagallo, M.I.C.; Gutz, I.G.R.

1990-01-01

With the aim of improving the sensitivity of the electroanalytical determination of uranium at trace levels. The uranium catalyzed reduction of nitrate on mercury electrode and the technique of chronocoulometry were used. Several experimental parameters were investigated (electrolyte composition, potential program, integration time, blank correction, temperature, previous separation) and adequate conditions were selected for the analytical determination. Under these conditions it was possible to exceed the best reported sensitivity for the catalytic determination, extending the detection limit to 3.10 -10 M. Exploratory study of the combination of this procedure with pre-concentration of uranium ions on the electrode revealed a detection limit ten limes lower. (author) [pt

Immobilization of Cu(II) in KIT-6 supported Co{sub 3}O{sub 4} and catalytic performance for epoxidation of styrene

Energy Technology Data Exchange (ETDEWEB)

Li, Baitao, E-mail: btli@scut.edu.cn; Luo, Xin; Zhu, Yanrun; Wang, Xiujun, E-mail: xjwangcn@scut.edu.cn

2015-12-30

Graphical abstract: - Highlights: • Cu-containing cobaltosic oxide composite supported by KIT-6 was synthesized. • Calcination temperature (250 and 550 °C) affected the catalyst structure. • Cu{sup 2+} was successfully embedded in spinel structure when calcined at 550 °C. • Hybrid CuO and Co{sub 3}O{sub 4} were remained in the catalyst through 250 °C treatment. • Enhancement in selectivity of styrene oxide was obtained for Cu-spinel catalyst. - Abstract: KIT-6 is a cage type three dimensional cubic mesoporous silicate with Ia3d type structure, which shows scintillating promise in nanocasting, surface functionality, metal incorporation, and pharmaceutics. Nevertheless, little attention was paid to its application as support in heterogeneous catalysts. Cu-containing cobaltosic oxide spinel composite supported by mesoporous silica KIT-6 was synthesized via impregnation method and subsequent calcination under different temperatures. The prepared ordered materials were characterized by X-ray diffraction, N{sub 2} adsorption–desorption, transmission electron microscopy, atomic adsorption spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results showed that Cu{sup 2+} was successfully embedded in spinel structure when calcined at 550 °C, in contrast, the samples through thermal treatment at 250 °C remained hybrid composition of CuO and Co{sub 3}O{sub 4}. Catalytic performance of mesoporous materials was evaluated for epoxidation of styrene in the presence of tert-butylhydroperoxide as oxidant. Among a range of prepared materials, a significant enhancement in styrene conversion and selectivity of styrene oxide was obtained for Cu-spinel catalysts, in comparison with hybrid oxide. A dramatic decrease in catalytic activities was found while KIT-6 support was removed, due to the partial destruction of ordered structure of Cu–Co oxide. Consequently, the catalytic behaviors were chiefly ascribed to copper species and their textural

Influence of selected washing treatments and drying temperatures ...

African Journals Online (AJOL)

Influence of selected washing treatments and drying temperatures on ... with regard to the optimal retention of the crude protein and fat levels of the dried dagaa. ... are accessible to most of the households involved in dried fish processing.

High-temperature catalytic reforming of n-hexane over supported and core-shell Pt nanoparticle catalysts: role of oxide-metal interface and thermal stability.

Science.gov (United States)

An, Kwangjin; Zhang, Qiao; Alayoglu, Selim; Musselwhite, Nathan; Shin, Jae-Youn; Somorjai, Gabor A

2014-08-13

Designing catalysts with high thermal stability and resistance to deactivation while simultaneously maintaining their catalytic activity and selectivity is of key importance in high-temperature reforming reactions. We prepared Pt nanoparticle catalysts supported on either mesoporous SiO2 or TiO2. Sandwich-type Pt core@shell catalysts (SiO2@Pt@SiO2 and SiO2@Pt@TiO2) were also synthesized from Pt nanoparticles deposited on SiO2 spheres, which were encapsulated by either mesoporous SiO2 or TiO2 shells. n-Hexane reforming was carried out over these four catalysts at 240-500 °C with a hexane/H2 ratio of 1:5 to investigate thermal stability and the role of the support. For the production of high-octane gasoline, branched C6 isomers are more highly desired than other cyclic, aromatic, and cracking products. Over Pt/TiO2 catalyst, production of 2-methylpentane and 3-methylpentane via isomerization was increased selectively up to 420 °C by charge transfer at Pt-TiO2 interfaces, as compared to Pt/SiO2. When thermal stability was compared between supported catalysts and sandwich-type core@shell catalysts, the Pt/SiO2 catalyst suffered sintering above 400 °C, whereas the SiO2@Pt@SiO2 catalyst preserved the Pt nanoparticle size and shape up to 500 °C. The SiO2@Pt@TiO2 catalyst led to Pt nanoparticle sintering due to incomplete protection of the TiO2 shells during the reaction at 500 °C. Interestingly, over the Pt/TiO2 catalyst, the average size of Pt nanoparticles was maintained even after 500 °C without sintering. In situ ambient pressure X-ray photoelectron spectroscopy demonstrated that the Pt/TiO2 catalyst did not exhibit TiO2 overgrowth on the Pt surface or deactivation by Pt sintering up to 600 °C. The extraordinarily high stability of the Pt/TiO2 catalyst promoted high reaction rates (2.0 μmol · g(-1) · s(-1)), which was 8 times greater than other catalysts and high isomer selectivity (53.0% of C6 isomers at 440 °C). By the strong metal-support interaction

Lattice Boltzmann simulation of endothermal catalytic reaction in catalyst porous media

International Nuclear Information System (INIS)

Li Xunfeng; Cai Jun; Xin Fang; Huai Xiulan; Guo Jiangfeng

2013-01-01

Gas catalytic reaction in a fixed bed reactor is a general process in chemical industry. The chemical reaction process involves the complex multi-component flow, heat and mass transfer coupling chemical reaction in the catalyst porous structure. The lattice Boltzmann method is developed to simulate the complex process of the surface catalytic reaction in the catalyst porous media. The non-equilibrium extrapolation method is used to treat the boundaries. The porous media is structured by Sierpinski carpet fractal structure. The velocity correction is adopted on the reaction surface. The flow, temperature and concentration fields calculated by the lattice Boltzmann method are compared with those computed by the CFD software. The effects of the inlet velocity, porosity and inlet components ratio on the conversion are also studied. Highlights: ► LBM is developed to simulate the surface catalytic reaction. ► The Sierpinski carpet structure is used to construct the porous media. ► The LBM results are in agreement with the CFD predictions. ► Velocity, temperature and concentration fields are obtained. ► Effects of the velocity, porosity and concentration on conversion are analyzed.

A kinetic study on non-catalytic reactions in hydroprocessing Boscan crude oil

Energy Technology Data Exchange (ETDEWEB)

A. Marafi; E. Kam; A. Stanislaus [Kuwait Institute for Scientific Research, Safat (Kuwait). Petroleum Refining Department, Petroleum Research and Studies Center

2008-08-15

Non-catalytic hydrothermal cracking reactions are known to associate with catalytic hydrocracking reactions. In a recent study on hydroprocessing of Boscan crude over a specific catalyst system containing three distinct catalysts, it was found that hydrodesulfurization (HDS) and hydrodemetallation (HDM) reactions continued even when the catalyst is severely deactivated. Since the reactor was packed with considerable amount of inert material besides the three catalysts, it will be advantage to determine if the inert materials can also facilitate hydroprocessing reactions. A series of kinetic experiments for the inert particles was undertaken under different space velocity and temperature conditions. The extent of catalytic and non-catalytic hydroprocessing reactions was assessed. Through statistical analysis, the initial reaction rate constant, reaction order and activation energy for various hydroprocessing reactions were then determined. The absolute average deviations (AAD) of the kinetics values obtained for inert materials are less than 10%. 25 refs., 7 figs., 4 tabs.

New process model proves accurate in tests on catalytic reformer

Energy Technology Data Exchange (ETDEWEB)

Aguilar-Rodriguez, E.; Ancheyta-Juarez, J. (Inst. Mexicano del Petroleo, Mexico City (Mexico))

1994-07-25

A mathematical model has been devised to represent the process that takes place in a fixed-bed, tubular, adiabatic catalytic reforming reactor. Since its development, the model has been applied to the simulation of a commercial semiregenerative reformer. The development of mass and energy balances for this reformer led to a model that predicts both concentration and temperature profiles along the reactor. A comparison of the model's results with experimental data illustrates its accuracy at predicting product profiles. Simple steps show how the model can be applied to simulate any fixed-bed catalytic reformer.

In situ and operando transmission electron microscopy of catalytic materials

DEFF Research Database (Denmark)

Crozier, Peter A.; Hansen, Thomas Willum

2015-01-01

measurements of gas-phase catalytic products. To overcome this deficiency, operando TEM techniques are being developed that combine atomic characterization with the simultaneous measurement of catalytic products. This article provides a short review of the current status and major developments......) is a powerful technique for revealing the atomic structures of materials at elevated temperatures in the presence of reactive gases. This approach can allow the structure-reactivity relations underlying catalyst functionality to be investigated. Thus far, ETEM has been limited by the absence of in situ...... in the application of ETEM to gas-phase catalysis over the past 10 years....

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)

Hydrothermal synthesis, structure, heterogeneous catalytic activity and photoluminescent properties of a novel homoleptic Sm(III)-organic framework

Energy Technology Data Exchange (ETDEWEB)

Ay, Burak [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Yildiz, Emel, E-mail: eeyildiz@cu.edu.tr [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Felts, Ashley C.; Abboud, Khalil A. [Department of Chemistry, University of Florida, Gainesville, FL 32611 (United States)

2016-12-15

A novel metal-organic framework, (H{sub 2}pip){sub n}[Sm{sub 2}(pydc){sub 4}(H{sub 2}O){sub 2}]{sub n} (1) (H{sub 2}pydc=2,6-pyridinedicarboxylic acid, H{sub 2}pip=piperazine) has been synthesized under hydrothermal conditions and characterized by the elemental analysis, inductively coupled plasma (ICP) spectrometer, fourier transform infrared (FT-IR) spectra, thermogravimetric analysis (TGA), single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). The structure of 1 was determined to be three-dimensional, linked along Sm-O-Sm chains. The asymmetric unit consisted of one singly anionic fragment consisting of Sm(III) coordinated to two H{sub 2}pydc ligands and one water, and one half of a protonated H{sub 2}pip, which sits on an inversion center. 1 exhibited luminescence emission bands at 534 nm at room temperature when excited at 440 nm. Its thermal behavior and catalytic performance were investigated and the selectivity was measured as 100% for the oxidation of thymol to thymoquinone. - Graphical abstract: A novel 3D lanthanide-organic framework has been synthesized under hydrothermal conditions. The thermal behavior and catalytic performance of 1 were investigated and its selectivity was measured as 100% for the oxidation of thymol to thymoquinone.

Significant Improvement of Catalytic Efficiencies in Ionic Liquids

International Nuclear Information System (INIS)

Song, Choong Eui; Yoon, Mi Young; Choi, Doo Seong

2005-01-01

The use of ionic liquids as reaction media can confer many advantages upon catalytic reactions over reactions in organic solvents. In ionic liquids, catalysts having polar or ionic character can easily be immobilized without additional structural modification and thus the ionic solutions containing the catalyst can easily be separated from the reagents and reaction products, and then, be reused. More interestingly, switching from an organic solvent to an ionic liquid often results in a significant improvement in catalytic performance (e.g., rate acceleration, (enantio)selectivity improvement and an increase in catalyst stability). In this review, some recent interesting results which can nicely demonstrate these positive 'ionic liquid effect' on catalysis are discussed

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)

Catalytic Activity Control via Crossover between Two Different Microstructures

KAUST Repository

Zhou, Yuheng

2017-09-08

Metal nanocatalysts hold great promise for a wide range of heterogeneous catalytic reactions, while the optimization strategy of catalytic activity is largely restricted by particle size or shape control. Here, we demonstrate that a reversible microstructural control through the crossover between multiply-twinned nanoparticle (MTP) and single crystal (SC) can be readily achieved by solvent post-treatment on gold nanoparticles (AuNPs). Polar solvents (e.g. water, methanol) direct the transformation from MTP to SC accompanied by the disappearance of twinning and stacking faults. A reverse transformation from SC to MTP is achieved in non-polar solvent (e.g. toluene) mixed with thiol ligands. The transformation between two different microstructures is directly observed by in-situ TEM and leads to a drastic modulation of catalytic activity towards the gas-phase selective oxidation of alcohols. There is a quasi-linear relationship between TOFs and MTP concentrations. Based on the combined experimental and theoretical investigations of alcohol chemisorption on these nanocatalysts, we propose that the exposure of {211}-like microfacets associated with twin boundaries and stack faults accounts for the strong chemisorption of alcohol molecules on MTP AuNPs and thus the exceptionally high catalytic activity.

Catalytic properties and radiothermoluminescence of calcium molybdate with MoO3 additives

International Nuclear Information System (INIS)

Popov, B.I.; Shkuratova, L.N.; Maksimov, Yu.V.; Gustov, V.V.

1982-01-01

Radiothermoluminescence (RTL) technique was used to examine the surface properties of calcium-molybdenum catalysts. Excess MoO 3 was added to stoichiometric calcium molybdate via impregnation of the latter by ammonium heptamolybdate and subsequent drying and calcination. Catalytic properties in methanol oxidation were determined by a flow-circulation technique at 623 K in the kinetic region. The samples were irradiated by a 57 Co source (1-2 Mrad) at the temperature of liquid nitrogen. RTL curves were recorded at temperatures varying within 100-260 K. The addition of excess MoO 3 to calcium molybdate leads to significant changes in catalytic properties and RTL, thus indicating either the healing of the surface defects of matrices or the formation of solid solutions. (Sz.J.)

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.

A catalytic approach to estimate the redox potential of heme-peroxidases

International Nuclear Information System (INIS)

Ayala, Marcela; Roman, Rosa; Vazquez-Duhalt, Rafael

2007-01-01

The redox potential of heme-peroxidases varies according to a combination of structural components within the active site and its vicinities. For each peroxidase, this redox potential imposes a thermodynamic threshold to the range of oxidizable substrates. However, the instability of enzymatic intermediates during the catalytic cycle precludes the use of direct voltammetry to measure the redox potential of most peroxidases. Here we describe a novel approach to estimate the redox potential of peroxidases, which directly depends on the catalytic performance of the activated enzyme. Selected p-substituted phenols are used as substrates for the estimations. The results obtained with this catalytic approach correlate well with the oxidative capacity predicted by the redox potential of the Fe(III)/Fe(II) couple

Oxyfuel combustion using a catalytic ceramic membrane reactor

Energy Technology Data Exchange (ETDEWEB)

Tan, Xiaoyao; Li, K. [Department of Chemical Engineering, Imperial College London, University of London, South Kensington, London SW7 2AZ (United Kingdom); Thursfield, A.; Metcalfe, I.S. [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom)

2008-02-29

Membrane catalytic combustion (MCC) is an environmentally friendly technique for heat and power generation from methane. This work demonstrates the performances of a MCC perovskite hollow fibre membrane reactor for the catalytic combustion of methane. The ionic-electronic La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{alpha}} (LSCF6428) mixed conductor, in the form of an oxygen-permeable hollow fibre membrane, has been prepared successfully by means of a phase-inversion spinning/sintering technique. For this process polyethersulfone (PESf) was used as a binder, N-methyl-2-pyrrollidone (NMP) as solvent and polyvinylpyrrolidone (PVP, K16-18) as an additive. With the prepared LSCF6428 hollow fibre membranes packed with catalyst, hollow fibre membrane reactors (HFMRs) have been assembled to perform the catalytic combustion of methane. A simple mathematical model that combines the local oxygen permeation rate with approximate catalytic reaction kinetics has been developed and can be used to predict the performance of the HFMRs for methane combustion. The effects of operating temperature and methane and air feed flow rates on the performance of the HFMR have been investigated both experimentally and theoretically. Both the methane conversion and oxygen permeation rate can be improved by means of coating platinum on the air side of the hollow fibre membranes. (author)

Numerical simulation of urea based selective non-catalytic reduction deNOx process for industrial applications

International Nuclear Information System (INIS)

Baleta, Jakov; Mikulčić, Hrvoje; Vujanović, Milan; Petranović, Zvonimir; Duić, Neven

2016-01-01

Highlights: • SNCR is a simple method for the NOx reduction from large industrial facilities. • Capabilities of the developed mathematical framework for SNCR simulation were shown. • Model was used on the geometry of experimental reactor and municipal incinerator. • Results indicate suitability of the developed model for real industrial cases. - Abstract: Industrial processes emit large amounts of diverse pollutants into the atmosphere, among which NOx takes a significant portion. Selective non-catalytic reduction (SNCR) is a relatively simple method for the NOx reduction in large industrial facilities such as power plants, cement plants and waste incinerator plants. It consists of injecting the urea-water solution in the hot flue gas stream and its reaction with the NOx. During this process flue gas enthalpy is used for the urea-water droplet heating and for the evaporation of water content. After water evaporates, thermolysis of urea occurs, during which ammonia, a known NO_x reductant, and isocyanic acid are generated. In order to cope with the ever stringent environmental norms, equipment manufacturers need to develop energy efficient products that are at the same time benign to environment. This is becoming increasingly complicated and costly, and one way to reduce production costs together with the maintaining the same competitiveness level is to employ computational fluid dynamics (CFD) as a tool, in a process today commonly known under the term “virtual prototyping”. The aim of this paper is to show capabilities of the developed mathematical framework implemented in the commercial CFD code AVL FIRE®, to simulate physical processes of all relevant phenomena occurring during the SNCR process. First, mathematical models for description of SNCR process are presented and afterwards, models are used on the 3D geometry of an industrial reactor and a real industrial case to predict SNCR efficiency, temperature and velocity field. Influence of the main

Steam reformer with catalytic combustor

Science.gov (United States)

Voecks, Gerald E. (Inventor)

1990-01-01

A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

Silver nanoparticles containing hybrid polymer microgels with tunable surface plasmon resonance and catalytic activity

Energy Technology Data Exchange (ETDEWEB)

Ajmal, Muhammad; Siddiq, Mohammad [Quaid-I-Azam University, Islamabad (Pakistan); Farooqi, Zahoor Hussain [University of the Punjab, Lahore (Pakistan)

2013-11-15

Multi-responsive poly(N-isopropylacrylamide-methacrylic acid-acrylamide) [P(NIPAM-MAA-AAm)] copolymer microgel was prepared by free radical emulsion polymerization. Silver nanoparticles were fabricated inside the microgel network by in-situ reduction of silver nitrate. Swelling and deswelling behavior of the pure microgels was studied under various conditions of pH and temperature using dynamic light scattering. A red shift was observed in surface plasmon resonance wavelength of Ag nanoparticles with pH induced swelling of hybrid microgel. The catalytic activity of the hybrid system was investigated by monitoring the reduction of p-nitrophenol under different conditions of temperature and amount of catalysts. For this catalytic reaction a time delay of 8 to 10min was observed at room temperature, which was reduced to 2 min at high temperature due to swelling of microgels, which facilitated diffusion of reactants to catalyst surface and increased rate of reaction.

Development of a coupled reactor with a catalytic combustor and steam reformer for a 5 kW solid oxide fuel cell system

International Nuclear Information System (INIS)

Kang, Sanggyu; Lee, Kanghun; Yu, Sangseok; Lee, Sang Min; Ahn, Kook-Young

2014-01-01

Highlights: • Proposes the scale-up strategy to develop a large-scale coupled reactor. • Investigation of performance of steam reformer coupled with catalytic combustor. • Experimental parameters are inlet temp., air excess ratio, SCR, fuel utilization. • Evaluation of the heat transfer distribution along the gas flow direction. • The mean value of methane conversion rate is approximately 93.4%. - Abstract: The methane (CH 4 ) conversion rate of a steam reformer can be increased by thermal integration with a catalytic combustor, called a coupled reactor. In the present study, a 5 kW coupled reactor has been developed based on a 1 kW coupled reactor in previous work. The geometric parameters of the space velocity, diameter and length of the coupled reactor selected from the 1 kW coupled reactor are tuned and applied to the design of the 5 kW coupled reactor. To confirm the scale-up strategy, the performance of 5 kW coupled reactor is experimentally investigated with variations of operating parameters such as the fuel utilization in the solid oxide fuel cell (SOFC) stack, the inlet temperature of the catalytic combustor, the excess air ratio of the catalytic combustor, and the steam to carbon ratio (SCR) in the steam reformer. The temperature distributions of coupled reactors are measured along the gas flow direction. The gas composition at the steam reformer outlet is measured to find the CH 4 conversion rate of the coupled reactor. The maximum value of the CH 4 conversion rate is approximately 93.4%, which means the proposed scale-up strategy can be utilized to develop a large-scale coupled reactor

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.

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.

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)

Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

OpenAIRE

Zheng, Bin; Liu, Yongqi; Liu, Ruixiang; Meng, Jian; Mao, Mingming

2015-01-01

This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h) and catalytic oxidation bed average temperature (20°C to 560°C) within the preheated catalytic oxidation reactor. The pressure drop and res...

Zeolitic catalytic conversion of alcohols to hydrocarbons

Science.gov (United States)

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2018-04-10

A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

Zeolitic catalytic conversion of alochols to hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2017-01-03

A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

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.

Enhancement in catalytic activity of Aspergillus niger XynB by selective site-directed mutagenesis of active site amino acids.

Science.gov (United States)

Wu, Xiuyun; Tian, Zhennan; Jiang, Xukai; Zhang, Qun; Wang, Lushan

2018-01-01

XynB from Aspergillus niger ATCC1015 (AnXynB) is a mesophilic glycoside hydrolase (GH) family 11 xylanase which holds great potentials in a wide variety of industrial applications. In the present study, the catalytic activity and stability of AnXynB were improved by a combination of computational and experimental approaches. Virtual mutation and molecular dynamics simulations indicated that the introduction of Glu and Asn altered the interaction network at the - 3 subsite. Interestingly, the double mutant S41N/T43E displayed 72% increase in catalytic activity when compared to the wild type (WT). In addition, it also showed a better thermostability than the WT enzyme. Kinetic determination of the T43E and S41N/T43E mutants suggested that the higher xylanase activity is probably due to the increasing binding affinity of enzyme and substrate. Consequently, the enzyme activity and thermostability of AnXynB was both increased by selective site-directed mutagenesis at the - 3 subsite of its active site architecture which provides a good example for a successfully engineered enzyme for potential industrial application. Moreover, the molecular evolution approach adopted in this study led to the design of a library of sequences that captures a meaningful functional diversity in a limited number of protein variants.

Enhanced catalytic performance for light-olefins production from chloromethane over hierarchical porous ZSM-5 zeolite synthesized by a growth-inhibition strategy

Science.gov (United States)

Liu, Qing; Wen, Dafen; Yang, Yanran; Fei, Zhaoyang; Zhang, Zhuxiu; Chen, Xian; Tang, Jihai; Cui, Mifen; Qiao, Xu

2018-03-01

Hierarchical porous ZSM-5 (HP-ZSM-5) zeolites were synthesized by hydrothermal crystallization method adding triethoxyvinylsilane as the growth-inhibitor at different hydrothermal crystallized temperatures. The properties of the obtained samples were characterized by XRD, SEM, N2-sorption, uptake of ethylene, 27Al MAS NMR, NH3-TPD, and Py-IR. It was found that the mesopore was introduced and the acidity was adjusted over HP-ZSM-5 samples successfully. The hydrothermal crystallized temperature had an important influence on the porous structure and surface properties. The catalytic performance for chloromethane to light-olefins (CMTO) were also investigated. Compared with ZSM-5 samples, HP-ZSM-5 samples exhibited enhanced stability and increased selectivity of light-olefins for CMTO reaction because of the introduction of the abundant mesopore and appropriate acidity. The lifetime (the duration of chloromethane conversion >98%) and selectivity of light-olefins reached 115 h and 69.3%, respectively.

Reducing NO(x) emissions from a nitric acid plant of domestic petrochemical complex: enhanced conversion in conventional radial-flow reactor of selective catalytic reduction process.

Science.gov (United States)

Abbasfard, Hamed; Hashemi, Seyed Hamid; Rahimpour, Mohammad Reza; Jokar, Seyyed Mohammad; Ghader, Sattar

2013-01-01

The nitric acid plant of a domestic petrochemical complex is designed to annually produce 56,400 metric tons (based on 100% nitric acid). In the present work, radial-flow spherical bed reactor (RFSBR) for selective catalytic reduction of nitric oxides (NO(x)) from the stack of this plant was modelled and compared with the conventional radial-flow reactor (CRFR). Moreover, the proficiency of a radial-flow (water or nitrogen) membrane reactor was also compared with the CRFR which was found to be inefficient at identical process conditions. In the RFSBR, the space between the two concentric spheres is filled by a catalyst. A mathematical model, including conservation of mass has been developed to investigate the performance of the configurations. The model was checked against the CRFR in a nitric acid plant located at the domestic petrochemical complex. A good agreement was observed between the modelling results and the plant data. The effects of some important parameters such as pressure and temperature on NO(x) conversion were analysed. Results show 14% decrease in NO(x) emission annually in RFSBR compared with the CRFR, which is beneficial for the prevention of NO(x) emission, global warming and acid rain.

A new 3DOM Ce-Fe-Ti material for simultaneously catalytic removal of PM and NOx from diesel engines.

Science.gov (United States)

Cheng, Ying; Liu, Jian; Zhao, Zhen; Song, Weiyu; Wei, Yuechang

2018-01-15

A new 3DOM material was designed and synthesized for the simultaneous removal of PM (soot particulates) and NOx from diesel engine exhausts. The catalytic purification taking place over the material with double efficacy is cost-efficient. The contact between solid PM and catalyst active site has been process intensified by 3DOM unique structure. 3DOM Ce 0.7 Fe 0.2 Ti 0.1 O 2 catalyst possess a high SCR activity and an excellent selectivity to N 2 , giving a maximum concentration of CO 2 at 385°C for PM combustion and 100% NO conversion in the temperature range of 281-425°C. The dual redox cycles (Fe 3+ +Ce 3+ ↔Fe 2+ +Ce 4+ ,Fe 3+ +Ti 3+ ↔Fe 2+ +Ti 4+ ) and the excellent reducibility and sufficient acid sites of catalysts play key roles for the highly catalytic performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Production of filamentous carbon and H{sub 2} by solarthermal catalytic cracking of CH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Kirillov, V; Kuvshinov, G [Boreskov Inst. of Catalysis (Russian Federation); Reller, A [Hamburg Univ., Hamburg (Germany); Steinfeld, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

The catalytic thermal decomposition of methane has been experimentally studied using high-temperature solar process heat. Nickel catalyst particles, fluidized in methane, were directly irradiated at the PSI solar furnace. Carbon deposition consisted of randomly interlaced filaments that grew as fibers and hollow nanotubes (of approx. 30 nm diameter) originating at each catalytic particle. (author) 4 figs., 7 refs.

Tunable and selective hydrogenation of furfural to furfuryl alcohol and cyclopentanone over Pt supported on biomass-derived porous heteroatom doped carbon.

Science.gov (United States)

Liu, Xiuyun; Zhang, Bo; Fei, Benhua; Chen, Xiufang; Zhang, Junyi; Mu, Xindong

2017-09-21

The search for and exploitation of efficient catalytic systems for selective conversion of furfural into various high value-added chemicals remains a huge challenge for green synthesis in the chemical industry. Here, novel Pt nanoparticles supported on bamboo shoot-derived porous heteroatom doped carbon materials were designed as highly active catalysts for controlled hydrogenation of furfural in aqueous media. The porous heteroatom doped carbon supported Pt catalysts were endowed with a large surface area with a hierarchical porous structure, a high content of nitrogen and oxygen functionalities, a high dispersion of the Pt nanoparticles, good water dispersibility and reaction stability. Benefiting from these features, the novel Pt catalysts displayed a high activity and controlled tunable selectivity for furfural hydrogenation to produce furfuryl alcohol and cyclopentanone in water. The product selectivity could be easily modulated by controlling the carbonization temperature of the porous heteroatom doped carbon support and the reaction conditions (temperature and H 2 pressure). Under mild conditions (100 °C, 1 MPa H 2 ), furfuryl alcohol was obtained in water with complete conversion of the furfural and an impressive furfuryl alcohol selectivity of >99% in the presence of Pt/NC-BS-500. A higher reaction temperature, in water, favored rearrangement of the furfural (FFA) with Pt/NC-BS-800 as the catalyst, which resulted in a high cyclopentanone yield of >76% at 150 °C and 3 MPa H 2 . The surface properties and pore structure of the heteroatom doped carbon support, adjusted using the carbonization temperature, might determine the interactions between the Pt nanoparticles, carbon support and catalytic reactants in water, which in turn could have led to a good selectivity control. The effect of different reaction temperatures and reaction times on the product selectivity was also explored. Combined with exploration of the distribution of the reaction products, a

Catalytic Fast Pyrolysis of Biomass Impregnated with Potassium Phosphate in a Hydrogen Atmosphere for the Production of Phenol and Activated Carbon

Science.gov (United States)

Lu, Qiang; Zhang, Zhen-xi; Wang, Xin; Guo, Hao-qiang; Cui, Min-shu; Yang, Yong-ping

2018-01-01

A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K3PO4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content. In addition, the pyrolytic solid residues were activated to prepare ACs with high specific surface areas. The results indicated that phenol could be obtained due to the synergistic effects of K3PO4 and hydrogen atmosphere, with the yield and selectivity reaching 5.3 wt% and 17.8% from catalytic fast pyrolysis of poplar wood with 8 wt% K3PO4 at 550°C in a hydrogen atmosphere. This technique was adaptable to different woody materials for phenol production. Moreover, gas product generated from the pyrolysis process was feasible to be recycled to provide the hydrogen atmosphere, instead of extra hydrogen supply. In addition, the pyrolytic solid residue was suitable for AC preparation, using CO2 activation method, the specific surface area was as high as 1,605 m2/g. PMID:29515994

[Kinetics of catalytic wet air oxidation of phenol in trickle bed reactor].

Science.gov (United States)

Li, Guang-ming; Zhao, Jian-fu; Wang, Hua; Zhao, Xiu-hua; Zhou, Yang-yuan

2004-05-01

By using a trickle bed reactor which was designed by the authors, the catalytic wet air oxidation reaction of phenol on CuO/gamma-Al2O3 catalyst was studied. The results showed that in mild operation conditions (at temperature of 180 degrees C, pressure of 3 MPa, liquid feed rate of 1.668 L x h(-1) and oxygen feed rate of 160 L x h(-1)), the removal of phenol can be over 90%. The curve of phenol conversion is similar to "S" like autocatalytic reaction, and is accordance with chain reaction of free radical. The kinetic model of pseudo homogenous reactor fits the catalytic wet air oxidation reaction of phenol. The effects of initial concentration of phenol, liquid feed rate and temperature for reaction also were investigated.

Metal-surfactant interaction as a tool to control the catalytic selectivity of Pd catalysts

NARCIS (Netherlands)

Perez-Coronado, A. M.; Calvo, L.; Baeza, J.A.; Palomar, J.; Lefferts, L.; Rodriguez, J-C.; Gilarranz, M.A.

2017-01-01

The catalytic activity of Palladium nanoparticles synthesized via sodium bis[2-ethylhexyl] sulfosuccinate (AOT)/isooctane reverse microemulsion was studied in nitrite reduction. The influence of reaction conditions and the synthesis and purification of the nanoparticles was evaluated. In the

Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

Directory of Open Access Journals (Sweden)

Xiangjin Kong

Full Text Available The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

Science.gov (United States)

Kong, Xiangjin; Liu, Junhai

2014-01-01

The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

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

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)

The Relationship Between Structural and Catalytic Activity of α and γ-Bismuth-Molybdate Catalysts for Partial Oxidation of Propylene to Acrolein

Science.gov (United States)

Fansuri, H.; Pham, G. H.; Wibawanta, S.; Zhang, D. K.; French, David

Bismuth-molybdate catalysts are known to be effective for catalytic partial oxidation of propylene to acrolein. Their properties and the kinetics and reaction mechanisms for acrolein production have been extensively studied, especially in their basic forms, such as α, β, and γ-bismuth-molybdate. Although the reaction mechanisms have been reported widely in the literature, a general agreement has not been reached, especially from a catalyst-structure point of view. The present contribution reports an effort to understand the structural changes of α and γ-bismuth-molybdate catalysts at varying temperatures as examined using high temperature XRD and to relate the catalyst performance (activity and selectivity) for propylene partial oxidation to acrolein. The XRD analysis was performed at temperature between 250 and 450°C in ambient atmosphere and the Rietveld refinement method was used to extract unit cell parameters. The results showed a distinct similarity between the shapes of the thermal expansion of the catalysts and their activity and selectivity curves, indicating a significant role that the catalyst interatomic structure plays in the overall reaction mechanism.

Removal of ammonia solutions used in catalytic wet oxidation processes.

Science.gov (United States)

Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

2003-08-01

Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

Investigation into the Catalytic Activity of Microporous and Mesoporous Catalysts in the Pyrolysis of Waste Polyethylene and Polypropylene Mixture

Directory of Open Access Journals (Sweden)

Kaixin Li

2016-06-01

Full Text Available Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil–5 (C-ZSM-5, highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5 and β-zeolite, Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs, Kanemite-derived folded silica (KFS-16B and well-ordered Al-SBA-15 (Al-SBA-15(wo were studied with waste polyethylene (PE and polypropylene (PP mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET, X-ray powder diffraction (XRD, and NH3-temperature programmed desorption (TPD. The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2–C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

Effect of NO2 and water on the catalytic oxidation of soot

DEFF Research Database (Denmark)

Christensen, Jakob Munkholt; Grunwaldt, Jan-Dierk; Jensen, Anker Degn

2017-01-01

The influence of adding NO2 to 10 vol% O2/N2 on non-catalytic soot oxidation and soot oxidation in intimate or loose contact with a catalyst has been investigated. In non-catalytic soot oxidation the oxidation rate is increased significantly at lower temperatures by NO2. For soot oxidation in tig...... exhibited a volcano-curve dependence on the heat of oxygen chemisorption, and among the tested pure metals and oxides Cr2O3 was the most active catalyst. Further improvements were achieved with a FeaCrbOx binary oxide catalyst....

The catalytic oxidation of organic contaminants in a packed bed reactor

NARCIS (Netherlands)

van de Beld, L.; Bijl, M.P.G.; Reinders, A.; van der Wert, B.; Westerterp, K.R.

1994-01-01

The catalytic oxidation of several hydrocarbons was studied over noble metal and metal oxide catalysts. A fast empirical method was developed to determine the minimum operating temperature required to guarantee complete conversion of the hydrocarbon. The influence of the operating parameters such as

Developing a Steady-state Kinetic Model for Industrial Scale Semi-Regenerative Catalytic Naphtha Reforming Process

Directory of Open Access Journals (Sweden)

Seif Mohaddecy, R.

2014-05-01

Full Text Available Due to the demand for high octane gasoline as a transportation fuel, the catalytic naphtha reformer has become one of the most important processes in petroleum refineries. In this research, the steady-state modelling of a catalytic fixed-bed naphtha reforming process to predict the momentous output variables was studied. These variables were octane number, yield, hydrogen purity, and temperature of all reforming reactors. To do such a task, an industrial scale semi-regenerative catalytic naphtha reforming unit was studied and modelled. In addition, to evaluate the developed model, the predicted variables i.e. outlet temperatures of reactors, research octane number, yield of gasoline and hydrogen purity were compared against actual data. The results showed that there is a close mapping between the actual and predicted variables, and the mean relative absolute deviation of the mentioned process variables were 0.38 %, 0.52 %, 0.54 %, 0.32 %, 4.8 % and 3.2 %, respectively.

Non-thermal plasmas for non-catalytic and catalytic VOC abatement

International Nuclear Information System (INIS)

Vandenbroucke, Arne M.; Morent, Rino; De Geyter, Nathalie; Leys, Christophe

2011-01-01

Highlights: → We review the current status of catalytic and non-catalytic VOC abatement based on a vast number of research papers. → The underlying mechanisms of plasma-catalysis for VOC abatement are discussed. → Critical process parameters that determine the influent are discussed and compared. - Abstract: This paper reviews recent achievements and the current status of non-thermal plasma (NTP) technology for the abatement of volatile organic compounds (VOCs). Many reactor configurations have been developed to generate a NTP at atmospheric pressure. Therefore in this review article, the principles of generating NTPs are outlined. Further on, this paper is divided in two equally important parts: plasma-alone and plasma-catalytic systems. Combination of NTP with heterogeneous catalysis has attracted increased attention in order to overcome the weaknesses of plasma-alone systems. An overview is given of the present understanding of the mechanisms involved in plasma-catalytic processes. In both parts (plasma-alone systems and plasma-catalysis), literature on the abatement of VOCs is reviewed in close detail. Special attention is given to the influence of critical process parameters on the removal process.

Catalytic co-pyrolysis of paper biomass and plastic mixtures (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) and product analysis

International Nuclear Information System (INIS)

Chattopadhyay, Jayeeta; Pathak, T.S.; Srivastava, R.; Singh, A.C.

2016-01-01

Catalytic co-pyrolysis of biomass and plastics (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) has been performed in a fixed-bed reactor in presence of cobalt based alumina, ceria and ceria-alumina catalysts to analyze the product distribution and selectivity. Catalysts are synthesized using co-precipitation method and characterized by BET (Brunauer–Emmett–Teller) surface area and XRD analysis. The effect of catalytic co-pyrolysis at different temperature with product distribution has been evaluated. The results have clearly shown the synergistic effect between biomass and plastics, the liquid products gradually increases forming with rise in the plastic content in the blend. Gaseous products have yielded most during pyrolysis of blend having biomass/plastics ratio of 5:1 with the presence of 40% Co/30% CeO_2/30% Al_2O_3 catalyst with hydrogen gas production touched its peak of 47 vol%. Catalytic performance enhanced with increase with the cobalt loading, with best performance attributing to 40% Co/30% CeO_2/30% Al_2O_3 catalyst. - Highlights: • Catalytic co-pyrolysis of biomass and plastics (HDPE, PP & PET) blends in fixed-bed reactor. • Strong synergistic effect evident between biomass and plastics. • Solid residue diminished with application of catalysts. • Aromatics and olefins production increases with higher plastic content. • More hydrogen production with application of catalysts with higher cobalt content.

Catalytic distillation process

Science.gov (United States)

Smith, L.A. Jr.

1982-06-22

A method is described for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C[sub 4] feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

Improving the temperature characteristics and catalytic efficiency of a mesophilic xylanase from Aspergillus oryzae, AoXyn11A, by iterative mutagenesis based on in silico design.

Science.gov (United States)

Li, Xue-Qing; Wu, Qin; Hu, Die; Wang, Rui; Liu, Yan; Wu, Min-Chen; Li, Jian-Fang

2017-12-01

To improve the temperature characteristics and catalytic efficiency of a glycoside hydrolase family (GHF) 11 xylanase from Aspergillus oryzae (AoXyn11A), its variants were predicted based on in silico design. Firstly, Gly 21 with the maximum B-factor value, which was confirmed by molecular dynamics (MD) simulation on the three-dimensional structure of AoXyn11A, was subjected to site-saturation mutagenesis. Thus, one variant with the highest thermostability, AoXyn11A G21I , was selected from the mutagenesis library, E. coli/Aoxyn11A G21X (X: any one of 20 amino acids). Secondly, based on the primary structure multiple alignment of AoXyn11A with seven thermophilic GHF11 xylanases, AoXyn11A Y13F or AoXyn11A G21I-Y13F , was designed by replacing Tyr 13 in AoXyn11A or AoXyn11A G21I with Phe. Finally, three variant-encoding genes, Aoxyn11A G21I , Aoxyn11A Y13F and Aoxyn11A G21I-Y13F , were constructed by two-stage whole-plasmid PCR method, and expressed in Pichia pastoris GS115, respectively. The temperature optimum (T opt ) of recombinant (re) AoXyn11A G21I-Y13F was 60 °C, being 5 °C higher than that of reAoXyn11A G21I or reAoXyn11A Y13F , and 10 °C higher than that of reAoXyn11A. The thermal inactivation half-life (t 1/2 ) of reAoXyn11A G21I-Y13F at 50 °C was 240 min, being 40-, 3.4- and 2.5-fold longer than those of reAoXyn11A, reAoXyn11A G21I and reAoXyn11A Y13F . The melting temperature (T m ) values of reAoXyn11A, reAoXyn11A G21I , reAoXyn11A Y13F and reAoXyn11A G21I-Y13F were 52.3, 56.5, 58.6 and 61.3 °C, respectively. These findings indicated that the iterative mutagenesis of both Gly21Ile and Tyr13Phe improved the temperature characteristics of AoXyn11A in a synergistic mode. Besides those, the catalytic efficiency (k cat /K m ) of reAoXyn11A G21I-Y13F was 473.1 mL mg -1 s -1 , which was 1.65-fold higher than that of reAoXyn11A.

Mn-Ce-V-WOx/TiO2 SCR Catalysts: Catalytic Activity, Stability and Interaction among Catalytic Oxides

Directory of Open Access Journals (Sweden)

Xuteng Zhao

2018-02-01

Full Text Available A series of Mn-Ce-V-WOx/TiO2 composite oxide catalysts with different molar ratios (active components/TiO2 = 0.1, 0.2, 0.3, 0.6 have been prepared by wet impregnation method and tested in selective catalytic reduction (SCR of NO by NH3 in a wide temperature range. These catalysts were also characterized by X-ray diffraction (XRD, Transmission Electron Microscope (TEM, in situ Fourier Transform infrared spectroscopy (in situ FTIR, H2-Temperature programmed reduction (H2-TPR and X-ray photoelectron spectroscopy (XPS. The results show the catalyst with a molar ratio of active components/TiO2 = 0.2 exhibits highest NO conversion value between 150 °C to 400 °C and good resistance to H2O and SO2 at 250 °C with a gas hourly space velocity (GHSV value of 40,000 h−1. Different oxides are well dispersed and interact with each other. NH3 and NO are strongly adsorbed on the catalyst surface and the adsorption of the reactant gas leads to a redox cycle with the valence state change among the surface oxides. The adsorption of SO2 on Mn4+ and Ce4+ results in good H2O and SO2 resistance of the catalyst, but the effect of Mn and Ce are more than superior water and sulfur resistance. The diversity of valence states of the four active components and their high oxidation-reduction performance are the main reasons for the high NO conversion in this system.

Microwave-assisted and carbonaceous catalytic pyrolysis of crude glycerol from biodiesel waste for energy production

International Nuclear Information System (INIS)

Ng, Jo-Han; Leong, Swee Kim; Lam, Su Shiung; Ani, Farid Nasir; Chong, Cheng Tung

2017-01-01

Highlights: • Crude glycerol is pyrolysed catalytically via microwave irradiation to produce bioenergy. • Carbonaceous catalyst elevates pyrolysis temperature and promotes selectivity towards H_2 production. • Synthesis gas consisting of mainly H_2 and CH_4 was predominantly produced at long residence time and high temperature. • Production of bio-oil consisting of oxygenated compounds peaks at intermediate carrier gas flow rate. • Energy profit analysis shows positive energy gained with increasing residence time and decreasing reaction temperature. - Abstract: Biodiesel proliferation as a sustainable fuel has led to a glut of crude glycerol as co-product. This scenario made a previously lucrative co-product in the food and pharmaceutical sectors into a bioresource waste. The present study investigates the utilisation of a microwave-assisted pyrolysis technique to convert crude glycerol from biodiesel waste into usable bioenergy source. Operating conditions ranged from a temperature of 300–800 °C at carrier gas flow rates of 100–2000 mL/min, with the effects of carbonaceous catalyst on the selectivity of reaction pathway being investigated. Within the aforementioned conditions, the proportion of products phases is mainly dependent on the residence time inside the quartz reactor, followed by the reaction temperature. This is due to the combined factors of the reaction sequence and provision of activation energy to change product phases. The third factor of carbonaceous catalyst shows a predisposition towards hydrogen gas selectivity, leading to a lower overall gaseous product mass when factoring in products from all phases. An analysis of the energy content revealed that overall energy profit increases with decreasing temperature and increasing residence time. This concurs with solid energy content increasing in the same conditions, while it increases for liquid and gaseous products with decreasing temperature and flow rate, respectively. The

Precursor type affecting surface properties and catalytic activity of sulfated zirconia

Directory of Open Access Journals (Sweden)

Zarubica Aleksandra R.

2007-01-01

Full Text Available Zirconium-hydroxide precursor samples are synthesized from Zr-hydroxide, Zr-nitrate, and Zr-alkoxide, by precipitation/impregnation, as well as by a modified sol-gel method. Precursor samples are further sulphated for the intended SO4 2- content of 4 wt.%, and calcined at 500-700oC. Differences in precursors’ origin and calcination temperature induce the incorporation of SO4 2- groups into ZrO2 matrices by various mechanisms. As a result, different amounts of residual sulphates are coupled with other structural, as well as surface properties, resulting in various catalytic activities of sulphated zirconia samples. Catalyst activity and selectivity are a complex synergistic function of tetragonal phase fraction, sulphates contents, textural and surface characteristics. Superior activity of SZ of alkoxide origin can be explained by a beneficial effect of meso-pores owing to a better accommodation of coke deposits.

Forced thermal cycling of catalytic reactions: experiments and modelling

DEFF Research Database (Denmark)

Jensen, Søren; Olsen, Jakob Lind; Thorsteinsson, Sune

2007-01-01

Recent studies of catalytic reactions subjected to fast forced temperature oscillations have revealed a rate enhancement increasing with temperature oscillation frequency. We present detailed studies of the rate enhancement up to frequencies of 2.5 Hz. A maximum in the rate enhancement is observed...... at about 1 Hz. A model for the rate enhancement that includes the surface kinetics and the dynamic partial pressure variations in the reactor is introduced. The model predicts a levelling off of the rate enhancement with frequency at about 1 Hz. The experimentally observed decrease above 1 Hz is explained...

Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

Directory of Open Access Journals (Sweden)

Bin Zheng

2015-01-01

Full Text Available This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h and catalytic oxidation bed average temperature (20°C to 560°C within the preheated catalytic oxidation reactor. The pressure drop and resistance proportion of catalytic oxidation bed, the heat exchanger preheating section, and the heat exchanger flue gas section were measured. In addition, based on a large number of experimental data, the empirical equations of flow resistance are obtained by the least square method. It can also be used in deriving much needed data for preheated catalytic oxidation designs when employed in industry.

Temperature effects on the electrohydrodynamic and electrokinetic behaviour of ion-selective nanochannels

International Nuclear Information System (INIS)

Wood, Jeffery A; Benneker, Anne M; Lammertink, Rob G H

2016-01-01

A non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations is used to study the influence of heating effects in the form of Joule heating and viscous dissipation and imposed temperature gradients on a microchannel/nanochannel system. The system is solved numerically under various cases in order to determine the influence of temperature-related effects on ion-selectivity, flux and fluid flow profiles, as well as coupling between these phenomena. It is demonstrated that for a larger reservoir system, the effects of Joule heating and viscous dissipation only become relevant for higher salt concentrations and electric field strengths than are compatible with ion-selectivity due to Debye layer overlap. More interestingly, it is shown that using different temperature reservoirs can have a strong influence on ion-selectivity, as well as the induced electrohydrodynamic flows. (paper)

Surface science study of selective ethylene epoxidation catalyzed by the Ag(110) surface: Structural sensitivity

International Nuclear Information System (INIS)

Campbell, C.T.

1984-01-01

The selective oxidation of ethylene to ethylene epoxide (C 2 H 4 +1/2O 2 →C 2 H 4 O) over Ag is the simplest example of kinetically controlled, selective heterogeneous catalysis. We have studied the steady-state kinetics and selectivity of this reaction for the first time on a clean, well-characterized Ag(110) surface by using a special apparatus which allows rapid (approx.20 s) transfer between a high-pressure catalytic microreactor and an ultrahigh vacuum surface analysis (AES, XPS, LEED, TDS) chamber. The effects of temperature and reactant pressures upon the rate and selectivity are virtually identical on Ag(110) and supported, high surface area Ag catalysts. The absolute specific rate (per Ag surface atom) is, however, some 100-fold higher for Ag(110) than for high surface area catalysts. This is related to the well-known structural sensitivity of this reaction. It is postulated that a small percentage of (110) planes (or [110]-like sites) are responsible for most of the catalytic activity of high surface area catalysts. The high activity of the (110) plane is attributed to its high sticking probability for dissociative oxygen adsorption, since the rate of ethylene epoxidation is shown in a related work [Ref. 1: C. T. Campbell and M. T. Paffett, Surf. Sci. (in press)] to be proportional to the coverage of atomically adsorbed oxygen at constant temperature and ethylene pressure

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.

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

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.

Dynamic frame selection for in vivo ultrasound temperature estimation during radiofrequency ablation

International Nuclear Information System (INIS)

Daniels, Matthew J; Varghese, Tomy

2010-01-01

Minimally invasive therapies such as radiofrequency ablation have been developed to treat cancers of the liver, prostate and kidney without invasive surgery. Prior work has demonstrated that ultrasound echo shifts due to temperature changes can be utilized to track the temperature distribution in real time. In this paper, a motion compensation algorithm is evaluated to reduce the impact of cardiac and respiratory motion on ultrasound-based temperature tracking methods. The algorithm dynamically selects the next suitable frame given a start frame (selected during the exhale or expiration phase where extraneous motion is reduced), enabling optimization of the computational time in addition to reducing displacement noise artifacts incurred with the estimation of smaller frame-to-frame displacements at the full frame rate. A region of interest that does not undergo ablation is selected in the first frame and the algorithm searches through subsequent frames to find a similarly located region of interest in subsequent frames, with a high value of the mean normalized cross-correlation coefficient value. In conjunction with dynamic frame selection, two different two-dimensional displacement estimation algorithms namely a block matching and multilevel cross-correlation are compared. The multi-level cross-correlation method incorporates tracking of the lateral tissue expansion in addition to the axial deformation to improve the estimation performance. Our results demonstrate the ability of the proposed motion compensation using dynamic frame selection in conjunction with the two-dimensional multilevel cross-correlation to track the temperature distribution.

Selective synthesis of vitamin K3 over mesoporous NbSBA-15 catalysts synthesized by an efficient hydrothermal method.

Science.gov (United States)

Selvaraj, M; Park, D-W; Kim, I; Kawi, S; Ha, C S

2012-08-28

Well hexagonally ordered NbSBA-15 catalysts synthesized by an efficient hydrothermal method were used, for the first time, for the selective synthesis of vitamin K(3) by liquid-phase oxidation of 2-methyl-1-naphthol (2MN1-OH) under various reaction conditions. The recyclable NbSBA-15 catalysts were also reused to find their catalytic activities. To investigate the leaching of non-framework niobium species on the surface of silica networks, the results of original and recyclable NbSBA-15 catalysts were correlated and compared. To find an optimum condition for the selective synthesis of vitamin K(3), the washed NbSBA-15(2.2pH) was extensively used in this reaction with various reaction parameters such as temperature, time and ratios of reactant (2M1N-OH to H(2)O(2)), and the obtained results were also demonstrated. Additionally, the liquid-phase oxidation of 2M1N-OH was carried out with different solvents to find the best solvent with a good catalytic activity. Based on the all catalytic studies, the vitamin K(3) selectivity (97.3%) is higher in NbSBA-15(2.2pH) than that of other NbSBA-15 catalysts, and the NbSBA-15(2.2pH) is found to be a highly active and eco-friendly heterogeneous catalyst for the selective synthesis of vitamin K(3).

Methane combustion in catalytic premixed burners

International Nuclear Information System (INIS)

Cerri, I.; Saracco, G.; Specchia, V.

1999-01-01

Catalytic premixed burners for domestic boiler applications were developed with the aim of achieving a power modularity from 10 to 100% and pollutant emissions limited to NO x 2 , where the combustion took place entirely inside the burner heating it to incandescence and allowing a decrease in the flame temperature and NO x emissions. Such results were confirmed through further tests carried out in a commercial industrial-scale boiler equipped with the conical panels. All the results, by varying the excess air and the heat power employed, are presented and discussed [it

Temperature influence on biodiesel production by non-catalytic transesterification; Influencia da temperatura na producao de biodiesel por transesterificacao nao catalitica

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Humberto N.M.; Oliveira, Thomas R; Sousa, Elisa M.B.D. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

2008-07-01

The main objective of this paper is to produce biodiesel using supercritical fluids through of the transesterification process without use of catalysts. It become easier the separation of the reaction products when compared with conventional method. In this work the influence of the temperature in the production of biodiesel from mamona oil was studied. Tree temperatures were studied (473.15 K, 523.15 K and 573.15 K) and the pressure (300 bar) and molar ratio (1:40) was keep constant during the process. Excess of Alcohol was used for this synthesis. The influence of temperature on the conversion and the reaction time was evaluated. The castor bean oil and biodiesel obtained were characterized in relation to their properties more significant. For results, higher conversions were found at higher temperatures (573.15 K), however can see a trend to the stability of reaction. The quality of the product was suitable for most properties evaluated. The equipment designed and built for this purpose was feasible but require some modifications to its optimization. The reaction of biodiesel production was confirmed, even without the addition of catalyst. It was the need to use a large excess of alcohol in relation to oil on this route without catalytic converters. In the case of the route of biodiesel production without the addition of catalysts, was felt the need to use excess alcohol in relation to the castor bean oil. (author)

Catalytic performance improvement of styrene hydrogenation in trickle bed reactor by using periodic operation

International Nuclear Information System (INIS)

Wongkia, Atittahn; Praserthdam, Piyasan; Assabumrungrat, Suttichai; Suriye, Kongkiat; Nonkhamwong, Anuwat

2013-01-01

We investigated the catalytic performance improvement of styrene hydrogenation in a trickle bed reactor by using periodic operation. The effects of cycle period and split on relative conversion, which is defined as styrene conversion obtained from periodic operation over that from steady state operation, were examined at various operating conditions including gas and average liquid flow rates, pressure and temperature. The experimental results reveal that both cycle period and split have strong influence on the catalytic performance. The fast mode (short cycle period) is a favorable condition. The improvement by the periodic operation becomes less pronounced for operations at high average liquid flow rate, pressure and temperature. From this study, a maximum improvement of styrene conversion of 18% is observed

Catalytic performance improvement of styrene hydrogenation in trickle bed reactor by using periodic operation

Energy Technology Data Exchange (ETDEWEB)

Wongkia, Atittahn; Praserthdam, Piyasan; Assabumrungrat, Suttichai [Chulalongkorn University, Bangkok (Thailand); Suriye, Kongkiat; Nonkhamwong, Anuwat [SCG Chemicals Co. Ltd., Bangkok (Thailand)

2013-03-15

We investigated the catalytic performance improvement of styrene hydrogenation in a trickle bed reactor by using periodic operation. The effects of cycle period and split on relative conversion, which is defined as styrene conversion obtained from periodic operation over that from steady state operation, were examined at various operating conditions including gas and average liquid flow rates, pressure and temperature. The experimental results reveal that both cycle period and split have strong influence on the catalytic performance. The fast mode (short cycle period) is a favorable condition. The improvement by the periodic operation becomes less pronounced for operations at high average liquid flow rate, pressure and temperature. From this study, a maximum improvement of styrene conversion of 18% is observed.

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.

Catalytic bioreactors and methods of using same

Science.gov (United States)

Worden, Robert Mark; Liu, Yangmu Chloe

2017-07-25

Various embodiments provide a bioreactor for producing a bioproduct comprising one or more catalytically active zones located in a housing and adapted to keep two incompatible gaseous reactants separated when in a gas phase, wherein each of the one or more catalytically active zones may comprise a catalytic component retainer and a catalytic component retained within and/or thereon. Each of the catalytically active zones may additionally or alternatively comprise a liquid medium located on either side of the catalytic component retainer. Catalytic component may include a microbial cell culture located within and/or on the catalytic component retainer, a suspended catalytic component suspended in the liquid medium, or a combination thereof. Methods of using various embodiments of the bioreactor to produce a bioproduct, such as isobutanol, are also provided.

The influence of a silica pillar in lamellar tetratitanate for selective catalytic reduction of NOx using NH3

International Nuclear Information System (INIS)

Nogueira da Cunha, Beatriz; Gonçalves, Alécia Maria; Gomes da Silveira, Rafael; Urquieta-González, Ernesto A.; Magalhães Nunes, Liliane

2015-01-01

Highlights: • Potassium ions significantly affected the SCR. • The introduction of silica in the catalyst promotes the NH 3 -SCR reaction. • The catalysts activities were not significantly influenced by SO 2 addition. - Abstract: Silica-pillared layered titanate (SiO 2 –Ti 4 O 9 ) was prepared by intercalating organosilanes into the interlayers of a layered K 2 Ti 4 O 9 followed by calcination at 500 °C. The lamellar titanates produced were used as a support to prepare vanadium catalysts (1 and 2 wt%) through wet impregnation for selective catalytic reduction (SCR) of NO. The catalysts were characterized using nitrogen adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (H 2 -TPR), nuclear magnetic resonance ( 29 Si NMR), and infrared spectroscopy (FT-IR). Reduction of NO by NH 3 was studied in a fixed-bed reactor packed with the catalysts and fed a mixture comprising 1% NH 3 , 1% NO, 10% O 2 , and 34 ppm SO 2 (when used) in helium. The results demonstrate that activity is correlated with the support, i.e., with acidic strength of catalysts. The potassium in the support, K 2 Ti 4 O 9 , significantly affected the reaction and level of vanadium species reduction. The catalyst (1VSiT) with 1 wt% vanadium impregnated on the SiO 2 –Ti 4 O 9 support reduced ∼80% of the NO. Approximately the same conversion rate was generated on the catalyst (2VSiT) with 2 wt% vanadium using the same support. The increased NH 3 adsorption demonstrate that introduction of silica in the catalyst promotes the NH 3 -SCR reaction. More importantly, 2VSiT and 1VSiT were strongly resistant to SO 2 poisoning

Catalytic conversion of light alkanes

Energy Technology Data Exchange (ETDEWEB)

Lyons, J.E.

1992-06-30

The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

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%.

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.

Catalytic Cracking of Used Palm Oil using Composite Zeolite

International Nuclear Information System (INIS)

Chang, W.H.; Tye, C.T.

2013-01-01

The rapid expansion of human society implies greater energy demand and environmental issues. In face of depletion energy resources, research is being carried out widely in order to convert the plant oil into biofuel. In this research, the production of liquid biofuels via catalytic cracking of used palm oil in the presence of composite zeolite was studied. The performance of composite zeolite of different properties in the reaction has been evaluated. The catalytic cracking reactions were carried out in a batch reactor at reaction temperature of 350 degree Celsius for an hour. In the present study, adjusting the ratio of meso porous coating to microporous zeolite and magnesium loading on composite zeolite catalyst were found to be able to increase the gasoline fraction and overall conversion of the reaction. (author)

Intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots and their application in the colorimetric detection of H2O2 and glucose

International Nuclear Information System (INIS)

Lin, Liping; Song, Xinhong; Chen, Yiying; Rong, Mingcong; Zhao, Tingting; Wang, Yiru; Jiang, Yaqi; Chen, Xi

2015-01-01

Highlights: • The highly intrinsic peroxidase-like catalytic activity of N-GQDs is revealed. • The activity of N-GQDs depended on pH, temperature and H 2 O 2 concentration. • The activity of N-GQDs has been used to the detection of H 2 O 2 and glucose. • This assay was suitable for the detection of glucose concentrations in real samples. - Abstract: In this paper, the highly intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots (N-GQDs) is revealed. This activity was greatly dependent on pH, temperature and H 2 O 2 concentration. The experimental results showed that the stable N-GQDs could be used for the detection of H 2 O 2 and glucose over a wide range of pH and temperature, offering a simple, highly selective and sensitive approach for their colorimetric sensing. The linearity between the analyte concentration and absorption ranged from 20 to 1170 μM for H 2 O 2 and 25 to 375 μM for glucose with a detection limit of 5.3 μM for H 2 O 2 and 16 μM for glucose. This assay was also successfully applied to the detection of glucose concentrations in diluted serum and fruit juice samples

Towards the rationalization of catalytic activity values by means of local hyper-softness on the catalytic site: a criticism about the use of net electric charges.

Science.gov (United States)

Ignacio Martínez-Araya, Jorge; Grand, André; Glossman-Mitnik, Daniel

2015-11-28

By means of the Spin-Polarized Conceptual Density Functional Theory (SP-CDFT), three 2,6-bis(imino)pyridine catalysts based on iron(II), used for polymerization of ethylene, were studied. The catalysts differed by the substituent group, bearing either -H, -NO2 or -OCH3. To date, catalytic activity, a purely experimental parameter measuring the mass of polyethylene produced per millimole of iron per time and pressure unit at a fixed temperature, has not been explained in terms of local hyper-softness. The latter is a purely theoretical parameter designed for quantifying electronic effects; it is measured using the metal atom responsible for the coordination process with the monomer (ethylene). Because steric effects are not relevant in these kinds of catalysts and only electronic effects drive the catalytic process, an interesting link is found between catalytic activity and the local hyper-softness condensed on the iron atom by means of four functionals (B3LYP, BP86, B97D, and VSXC). This work demonstrates that the use of local hyper-softness, predicted by the SP-CDFT, is a suitable parameter for explaining order relationships among catalytic activity values, thus quantifying the electronic influence of the substituent group inducing this difference; the use of only net electric charges does not lead to clear conclusions. This finding can aid in estimating catalytic activities leading to a more rational design of new catalysts via computational chemistry.

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

Highly selective and sensitive paper-based colorimetric sensor using thiosulfate catalytic etching of silver nanoplates for trace determination of copper ions.

Science.gov (United States)

Chaiyo, Sudkate; Siangproh, Weena; Apilux, Amara; Chailapakul, Orawon

2015-03-25

A novel, highly selective and sensitive paper-based colorimetric sensor for trace determination of copper (Cu(2+)) ions was developed. The measurement is based on the catalytic etching of silver nanoplates (AgNPls) by thiosulfate (S2O3(2-)). Upon the addition of Cu(2+) to the ammonium buffer at pH 11, the absorption peak intensity of AuNPls/S2O3(2-) at 522 nm decreased and the pinkish violet AuNPls became clear in color as visible to the naked eye. This assay provides highly sensitive and selective detection of Cu(2+) over other metal ions (K(+), Cr(3+), Cd(2+), Zn(2+), As(3+), Mn(2+), Co(2+), Pb(2+), Al(3+), Ni(2+), Fe(3+), Mg(2+), Hg(2+) and Bi(3+)). A paper-based colorimetric sensor was then developed for the simple and rapid determination of Cu(2+) using the catalytic etching of AgNPls. Under optimized conditions, the modified AgNPls coated at the test zone of the devices immediately changes in color in the presence of Cu(2+). The limit of detection (LOD) was found to be 1.0 ng mL(-1) by visual detection. For semi-quantitative measurement with image processing, the method detected Cu(2+) in the range of 0.5-200 ng mL(-1)(R(2)=0.9974) with an LOD of 0.3 ng mL(-1). The proposed method was successfully applied to detect Cu(2+) in the wide range of real samples including water, food, and blood. The results were in good agreement according to a paired t-test with results from inductively coupled plasma-optical emission spectrometry (ICP-OES). Copyright © 2015. Published by Elsevier B.V.

Size Control of Iron Oxide Nanoparticles Using Reverse Microemulsion Method: Morphology, Reduction, and Catalytic Activity in CO Hydrogenation

Directory of Open Access Journals (Sweden)

Mohammad Reza Housaindokht

2013-01-01

Full Text Available Iron oxide nanoparticles were prepared by microemulsion method and evaluated in Fischer-Tropsch synthesis. The precipitation process was performed in a single-phase microemulsion operating region. Different HLB values of surfactant were prepared by mixing of sodium dodecyl sulfate (SDS and Triton X-100. Transmission electron microscopy (TEM, surface area, pore volume, average pore diameter, pore size distribution, and XRD patterns were used to analyze size distribution, shape, and structure of precipitated hematite nanoparticles. Furthermore, temperature programmed reduction (TPR and catalytic activity in CO hydrogenation were implemented to assess the performance of the samples. It was found that methane and CO2 selectivity and also the syngas conversion increased as the HLB value of surfactant decreased. In addition, the selectivity to heavy hydrocarbons and chain growth probability (α decreased by decreasing the catalyst crystal size.

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.

Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

Energy Technology Data Exchange (ETDEWEB)

Son, Jung Ik; Kim, Aram; Noh, Hui Bog; Lee, Hyun Ju; Shim, Yoon Bo; Park, Kang Hyun [Pusan National University, Busan (Korea, Republic of)

2012-01-15

The ruthenium(II) complex [Ru(bpy){sub 2}-(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus.

Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

International Nuclear Information System (INIS)

Son, Jung Ik; Kim, Aram; Noh, Hui Bog; Lee, Hyun Ju; Shim, Yoon Bo; Park, Kang Hyun

2012-01-01

The ruthenium(II) complex [Ru(bpy) 2 -(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus

Ni/MgAlO regeneration for catalytic wet air oxidation of an azo-dye in trickle-bed reaction

International Nuclear Information System (INIS)

Vallet, Ana; Ovejero, Gabriel; Rodríguez, Araceli; Peres, José A.; García, Juan

2013-01-01

Highlights: ► Ni supported over hydrotalcite calcined precursors as catalyst. ► Catalytic wet air oxidation in trickle bed reactor for Chromotrope 2R removal. ► Dye removal depends on temperature, initial dye concentration and flow rate. ► The catalyst proved to bare-usable after in situ regeneration. -- Abstract: Active nickel catalysts (7 wt%) supported over Mg–Al mixed oxides have been recently developed and it has also been demonstrated that they are also highly selective in Catalytic Wet air Oxidation (CWAO) of dyes. CWAO of Chromotrope 2R (C2R) has been studied using a trickle bed reactor employing temperatures from 100 to 180 °C, liquid flow rates from 0.1 to 0.7 mL min −1 and initial dye concentration from 10 to 50 ppm. Total pressure and air flow were 25 bar and 300 mL min −1 , respectively. The catalyst showed a very stable activity up to 24 h on stream with an average TOC conversion of 82% at 150 °C and T r = 0.098 g Ni min mL −1 . After the reaction, a 1.1 wt% C of carbonaceous deposit is formed onto the catalyst and a diminution of 30% of the surface area with respect of the fresh catalyst was observed. An increase in the space time gave higher TOC conversions up to T r = 0.098 g Ni min mL −1 , attaining values of 80% at 180 °C. The performance of TOC and dye removal does not decrease after two regeneration cycles. In total, a 57 h effective reaction has been carried out with no loss of catalytic activity

Ni/MgAlO regeneration for catalytic wet air oxidation of an azo-dye in trickle-bed reaction

Energy Technology Data Exchange (ETDEWEB)

Vallet, Ana [Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Ovejero, Gabriel, E-mail: govejero@quim.ucm.es [Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Rodríguez, Araceli [Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Peres, José A. [Centro de Química de Vila Real, Universidade de Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal); García, Juan, E-mail: juangcia@quim.ucm.es [Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain)

2013-01-15

Highlights: ► Ni supported over hydrotalcite calcined precursors as catalyst. ► Catalytic wet air oxidation in trickle bed reactor for Chromotrope 2R removal. ► Dye removal depends on temperature, initial dye concentration and flow rate. ► The catalyst proved to bare-usable after in situ regeneration. -- Abstract: Active nickel catalysts (7 wt%) supported over Mg–Al mixed oxides have been recently developed and it has also been demonstrated that they are also highly selective in Catalytic Wet air Oxidation (CWAO) of dyes. CWAO of Chromotrope 2R (C2R) has been studied using a trickle bed reactor employing temperatures from 100 to 180 °C, liquid flow rates from 0.1 to 0.7 mL min{sup −1} and initial dye concentration from 10 to 50 ppm. Total pressure and air flow were 25 bar and 300 mL min{sup −1}, respectively. The catalyst showed a very stable activity up to 24 h on stream with an average TOC conversion of 82% at 150 °C and T{sub r} = 0.098 g{sub Ni} min mL{sup −1}. After the reaction, a 1.1 wt% C of carbonaceous deposit is formed onto the catalyst and a diminution of 30% of the surface area with respect of the fresh catalyst was observed. An increase in the space time gave higher TOC conversions up to T{sub r} = 0.098 g{sub Ni} min mL{sup −1}, attaining values of 80% at 180 °C. The performance of TOC and dye removal does not decrease after two regeneration cycles. In total, a 57 h effective reaction has been carried out with no loss of catalytic activity.

Kinetic Study of the Catalytic Pyrolysis of Oil-Containing Waste

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Kirill Chalov

2016-10-01

Full Text Available Basing on the experimental data the optimal parameters of the pyrolysis of heavy and residual hydrocarbons of oil were defined as follows: temperature of 500 °С; catalyst  of CoCl2 with the catalyst loading 5% (wt. of the substrate weight. Under the optimal conditions the kinetic investigation of the pyrolysis process was carried out using the thermogravimetric method. According to the investigation, it was found that the activation energy of the catalytic pyrolysis of oil-containing waste decreased by 20-30 kJ/mol in comparison to non-catalytic process. Copyright © 2016 BCREC GROUP. All rights reserved Received: 13th July 2015; Revised: 25th March 2016; Accepted: 1st April 2016 How to Cite: Chalov, K., Lugovoy, Y., Kosivtsov, Y., Sulman, M., Sulman, E., Matveeva, V., Stepacheva, A. (2016. Kinetic Study of the Catalytic Pyrolysis of Oil-Containing Waste. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 330-338 (doi:10.9767/bcrec.11.3.572.330-338 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.572.330-338

Partial catalytic oxidation of CH{sub 4} to synthesis gas for power generation - Final report

Energy Technology Data Exchange (ETDEWEB)

Mantzaras, I.; Schneider, A.

2006-03-15

The partial oxidation of methane to synthesis gas over rhodium catalysts has been investigated experimentally and numerically in the pressure range of 4 to 10 bar. The methane/oxidizer feed has been diluted with large amounts of H{sub 2}O and CO{sub 2} (up to 70% vol.) in order to simulate new power generation cycles with large exhaust gas recycle. Experiments were carried out in an optically accessible channel-flow reactor that facilitated laser-based in situ measurements, and also in a subscale gas-turbine catalytic reactor. Full-elliptic steady and transient two-dimensional numerical codes were used, which included elementary hetero-/homogeneous chemical reaction schemes. The following are the key conclusions: a) Heterogeneous (catalytic) and homogeneous (gas-phase) schemes have been validated for the partial catalytic oxidation of methane with large exhaust gas recycle. b) The impact of added H{sub 2}O and CO{sub 2} has been elucidated. The added H{sub 2}O increased the methane conversion and hydrogen selectivity, while it decreased the CO selectivity. The chemical impact of CO{sub 2} (dry reforming) was minimal. c) The numerical model reproduced the measured catalytic ignition times. It was further shown that the chemical impact of H{sub 2}O and CO{sub 2} on the catalytic ignition delay times was minimal. d) The noble metal dispersion increased with different support materials, in the order Rh/{alpha}-Al{sub 2}O{sub 3}, Rh/ZrO{sub 2}, and Rh/Ce-ZrO{sub 2}. An evident relationship was established between the noble metal dispersion and the catalytic behavior. (authors)

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)

Catalytic Reforming of Oxygenates: State of the Art and Future Prospects.

Science.gov (United States)

Li, Di; Li, Xinyu; Gong, Jinlong

2016-10-12

This Review describes recent advances in the design, synthesis, reactivity, selectivity, structural, and electronic properties of the catalysts for reforming of a variety of oxygenates (e.g., from simple monoalcohols to higher polyols, then to sugars, phenols, and finally complicated mixtures like bio-oil). A comprehensive exploration of the structure-activity relationship in catalytic reforming of oxygenates is carried out, assisted by state-of-the-art characterization techniques and computational tools. Critical emphasis has been given on the mechanisms of these heterogeneous-catalyzed reactions and especially on the nature of the active catalytic sites and reaction pathways. Similarities and differences (reaction mechanisms, design and synthesis of catalysts, as well as catalytic systems) in the reforming process of these oxygenates will also be discussed. A critical overview is then provided regarding the challenges and opportunities for research in this area with a focus on the roles that systems of heterogeneous catalysis, reaction engineering, and materials science can play in the near future. This Review aims to present insights into the intrinsic mechanism involved in catalytic reforming and provides guidance to the development of novel catalysts and processes for the efficient utilization of oxygenates for energy and environmental purposes.

High aspect ratio catalytic reactor and catalyst inserts therefor

Science.gov (United States)

Lin, Jiefeng; Kelly, Sean M.

2018-04-10

The present invention relates to high efficient tubular catalytic steam reforming reactor configured from about 0.2 inch to about 2 inch inside diameter high temperature metal alloy tube or pipe and loaded with a plurality of rolled catalyst inserts comprising metallic monoliths. The catalyst insert substrate is formed from a single metal foil without a central supporting structure in the form of a spiral monolith. The single metal foil is treated to have 3-dimensional surface features that provide mechanical support and establish open gas channels between each of the rolled layers. This unique geometry accelerates gas mixing and heat transfer and provides a high catalytic active surface area. The small diameter, high aspect ratio tubular catalytic steam reforming reactors loaded with rolled catalyst inserts can be arranged in a multi-pass non-vertical parallel configuration thermally coupled with a heat source to carry out steam reforming of hydrocarbon-containing feeds. The rolled catalyst inserts are self-supported on the reactor wall and enable efficient heat transfer from the reactor wall to the reactor interior, and lower pressure drop than known particulate catalysts. The heat source can be oxygen transport membrane reactors.

Dimension meditated optic and catalytic performance over vanadium pentoxides

International Nuclear Information System (INIS)

Su, Dezhi; Zhao, Yongjie; Zhang, Ruibo; Ning, Mingqiang; Zhao, Yuzhen; Zhou, Heping; Li, Jingbo; Jin, Haibo

2016-01-01

Highlights: • V_2O_5 with diverse dimensional morphologies were synthesized. • The optic properties of diverse dimensional V_2O_5 were investigated in detail. • The catalytic properties of diverse dimensional V_2O_5 on the thermal decomposition of ammonium perchlorate were analyzed. - Abstract: Morphologies and sizes of V_2O_5 had crucial effect on their optic and catalytic performance. Diverse dimensional V_2O_5 were successfully synthesized by the combination of a hydrothermal and post heat treatment method. The as-obtained samples were characterized by X-ray power diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectra. Moreover, the optic properties of diverse dimensional V_2O_5 were examined by Fourier transform imaging spectrometer and UV–vis-spectrophotometer. It showed that the IR transmittance of nanowire (at 1019 cm"−"1 is 85%) and UV absorbance of microflowers (at 480 nm) were high. Furthermore, the catalytic properties of diverse dimensional V_2O_5 on the thermal decomposition of ammonium perchlorate were evaluated and compared by Thermo-Gravimetric Analysis and Differential Scanning Calorimetry. Moreover, the best catalytic performance was obtained with the morphology of nanowire. It showed the thermal decomposition temperatures of AP with nanowire, microflowers and microsphere were reduced to 373 °C, 382 °C and 376 °C (decreased by 52 °C, 43 °C and 49 °C).

Dimension meditated optic and catalytic performance over vanadium pentoxides