Deactivation of SCR catalysts in biomass fired power plants

DEFF Research Database (Denmark)

Olsen, Brian Kjærgaard

composition and operating conditions, is not available. The main objective of the work presented in this thesis has been to conduct an in depth investigation of the deactivation mechanism of vanadia based SCR catalysts, when subjected to potassium rich aerosols. It has furthermore been a goal to suggest...... for up to 600 hours. The activity of fresh and exposed catalysts was measured in the temperature range 250-400 °C in a laboratory-scale reactor. All samples exposed for more than 240 hours proved to have deactivated significantly, however, catalysts exposed at 150 °C showed higher remaining activity......-scale setup at 350 °C for up to 1100 hours, and their activities were followed by in situ measurements. A 3%V2O5-7%WO3/TiO2 reference catalyst deactivated with a rate of 0.91 %/day during 960 hours of exposure, and a subsequent SEM-EDS analysis showed complete potassium penetration of the catalyst wall...

Heteropoly acid promoted catalyst for SCR of NOx with ammonia

DEFF Research Database (Denmark)

2012-01-01

The present invention concerns the selective removal of nitrogen oxides (NOx) from gases. In particular, the invention concerns a process, a highly alkali metal resistant heteropoly acid promoted catalyst and the use of said catalyst for removal of NOx from exhaust or flue gases, said gases...... comprising alkali or earth alkali metals. Such gases comprise for example flue gases arising from the burning of biomass, combined biomass and fossil fuel, and from waste incineration units. The process comprises the selective catalytic reduction (SCR) of NOx, such as nitrogen dioxide (NO2) and nitrogen...

Impacts of halogen additions on mercury oxidation, in a slipstream selective catalyst reduction (SCR), reactor when burning sub-bituminous coal.

Science.gov (United States)

Cao, Yan; Gao, Zhengyang; Zhu, Jiashun; Wang, Quanhai; Huang, Yaji; Chiu, Chengchung; Parker, Bruce; Chu, Paul; Pant, Wei-Ping

2008-01-01

This paper presents a comparison of impacts of halogen species on the elemental mercury (Hg(0)) oxidation in a real coal-derived flue gas atmosphere. It is reported there is a higher percentage of Hg(0) in the flue gas when burning sub-bituminous coal (herein Powder River Basin (PRB) coal) and lignite, even with the use of selective catalytic reduction (SCR). The higher Hg(0)concentration in the flue gas makes it difficult to use the wet-FGD process for the mercury emission control in coal-fired utility boilers. Investigation of enhanced Hg(0) oxidation by addition of hydrogen halogens (HF, HCl, HBr, and HI) was conducted in a slipstream reactor with and without SCR catalysts when burning PRB coal. Two commercial SCR catalysts were evaluated. SCR catalyst no. 1 showed higher efficiencies of both NO reduction and Hg(0) oxidation than those of SCR catalyst no. 2. NH3 addition seemed to inhibit the Hg(0) oxidation, which indicated competitive processes between NH3 reduction and Hg(0) oxidation on the surface of SCR catalysts. The hydrogen halogens, in the order of impact on Hg(0) oxidation, were HBr, HI, and HCl or HF. Addition of HBr at approximately 3 ppm could achieve 80% Hg(0) oxidation. Addition of HI at approximately 5 ppm could achieve 40% Hg(0) oxidation. In comparison to the empty reactor, 40% Hg(0) oxidation could be achieved when HCl addition was up to 300 ppm. The enhanced Hg(0) oxidation by addition of HBr and HI seemed not to be correlated to the catalytic effects by both evaluated SCR catalysts. The effectiveness of conversion of hydrogen halogens to halogen molecules or interhalogens seemed to be attributed to their impacts on Hg(0) oxidation.

Monitoring the ammonia loading of zeolite-based ammonia SCR catalysts by a microwave method

Energy Technology Data Exchange (ETDEWEB)

Reiss, S.; Schoenauer, D.; Hagen, G.; Moos, R. [University of Bayreuth, Department of Functional Materials, Bayreuth (Germany); Fischerauer, G. [University of Bayreuth, Department of Metrology and Control, Bayreuth (Germany)

2011-05-15

Exhaust gas aftertreatment systems, which reduce nitrogen oxide emissions of heavy-duty diesel engines, commonly use a selective catalytic reduction (SCR) catalyst. Currently, emissions are controlled by evaluating NO{sub x} or NH{sub 3} in the gas phase downstream the catalyst and calculating the NH{sub 3} loading via a chemical storage model. Here, a microwave-cavity perturbation method is proposed in which electromagnetic waves are excited by probe feeds and the reflected signals are measured. At distinct resonance frequencies, the reflection coefficient shows a pronounced minimum. These resonance frequencies depend almost linearly on the NH{sub 3} loading of a zeolite-based SCR catalyst. Since the NH{sub 3} loading-dependent electrical properties of the catalyst material itself are measured, the amount of stored ammonia can be determined directly and in situ. The cross-sensitivity towards water can be reduced almost completely by selecting an appropriate frequency range. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the activation of Pt/Al2O3 catalysts in HC-SCR by sintering. Determination of redox-active sites using Multitrack

International Nuclear Information System (INIS)

Vaccaro, A.R.; Mul, G.; Moulijn, J.A.; Perez-Ramirez, J.

2003-01-01

A highly dispersed Pt/Al 2 O 3 catalyst was used for the selective catalytic reduction of NO x using propene (HC-SCR). Contact with the reaction gas mixture led to a significant activation of the catalyst at temperatures above 523K. According to CO chemisorption data and HRTEM analysis, Pt particles on the activated catalyst had sintered. The redox behavior of the fresh and sintered catalysts was investigated using Multitrack, a TAP-like pulse reactor. If Pt particles on the catalyst are highly dispersed (average size below =2nm), only a small part (=10%) of the total number of Pt surface sites as determined by CO chemisorption (Pt surf ) participates in H 2 /O 2 redox cycles (Pt surf,redox ) in Multitrack conditions. For a sintered catalyst, with an average particle size of 2.7nm, the number of Pt surf and Pt surf,redox sites are in good agreement. Similar results were obtained for both catalysts using NO as the oxidant. The low number of Pt surf,redox sites on highly dispersed Pt/Al 2 O 3 is explained by the presence of a kinetically more stable-probably ionic-form of Pt-O bonds on all surface sites of the smaller Pt particles, including corner, edge and terrace sites. When the average particle size shifts to =2.7nm, the kinetic stability of all Pt-O bonds is collectively decreased, enabling the participation of all Pt surface sites in the redox cycles. A linear correlation between the NO x conversion in HC-SCR, and the amount of Pt surf,redox was found. This suggests that redox-active Pt sites are necessary for catalytic activity. In addition, the correlation could be significantly improved by assuming that Pt surf,terrace sites of the particles larger than 2.7nm are mainly responsible for HC-SCR activity in steady state conditions. Implications of these results for the pathway of HC-SCR over Pt catalysts are discussed

Simultaneous removal of NO and Hg{sup 0} over Ce-Cu modified V{sub 2}O{sub 5}/TiO{sub 2} based commercial SCR catalysts

Energy Technology Data Exchange (ETDEWEB)

Chi, Guilong [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); College of Environmental Science & Engineering, Nankai University, Tianjin 300350 (China); Shen, Boxiong, E-mail: shenbx@nankai.edu.cn [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); Yu, Ranran [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); He, Chuan; Zhang, Xiao [College of Environmental Science & Engineering, Nankai University, Tianjin 300350 (China)

2017-05-15

Highlights: • Simultaneous removal of NO and Hg{sup 0} over the novel modified commercial SCR catalysts. • 7% Ce-1% Cu/SCR catalyst exhibited excellent activity of NO conversion and Hg{sup 0} oxidation. • 7% Ce-1% Cu/SCR catalyst showed higher resistance to SO{sub 2} and H{sub 2}O than other catalysts. • The synergistic interaction between Ce and Cu in the catalyst improved the activity greatly. - Abstract: A series of novel Ce-Cu modified V{sub 2}O{sub 5}/TiO{sub 2} based commercial SCR catalysts were prepared via ultrasonic-assisted impregnation method for simultaneous removal of NO and elemental mercury (Hg{sup 0}). Nitrogen adsorption, X-ray diffraction (XRD), temperature programmed reduction of H{sub 2} (H{sub 2}-TPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. 7% Ce-1% Cu/SCR catalyst exhibited the highest NO conversion efficiency (>97%) at 200–400 °C, as well as the best Hg{sup 0} oxidation activity (>75%) at 150–350 °C among all the catalysts. The XPS and H{sub 2}-TPR results indicated that 7% Ce-1% Cu/SCR possess abundant chemisorbed oxygen and good redox ability, which was due to the strong synergy between Ce and Cu in the catalyst. The existence of the redox cycle of Ce{sup 4+} + Cu{sup 1+} ↔ Ce{sup 3+} + Cu{sup 2+} could greatly improve the catalytic activity. 7% Ce-1% Cu/SCR showed higher resistance to SO{sub 2} and H{sub 2}O than other catalysts. NO has a promoting effect on Hg{sup 0} oxidation. The Hg{sup 0} oxidation activity was inhibited by the injection of NH{sub 3}, which was due to the competitive adsorption and oxidized mercury could be reduced by ammonia at temperatures greater than 325 °C. Therefore, Hg{sup 0} oxidation could easily occurred at the outlet of SCR catalyst layer due to the consumption of NH{sub 3}.

Parameter estimation and analysis of an automotive heavy-duty SCR catalyst model

DEFF Research Database (Denmark)

Åberg, Andreas; Widd, Anders; Abildskov, Jens

2017-01-01

A single channel model for a heavy-duty SCR catalyst was derived based on first principles. The model considered heat and mass transfer between the channel gas phase and the wash coat phase. The parameters of the kinetic model were estimated using bench-scale monolith isothermal data. Validation ...

Redox behaviour of vanadium during hydrogen-oxygen exposure of the V2O5-WO3/TiO2 SCR catalyst at 250 degrees C

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren B.; Mikolajska, Ewelina

2011-01-01

of H-2 (0-2%) in an 8% O-2/N-2 mixture, where the SCR activity was measured before and after the hydrogen treatment. The results show that the activity of the SCR catalyst is only negligibly affected during exposure to the H-2/O-2 gas and in all cases it returned reversibly to the initial NOx...... conversion rate after reexposure to the standard NH3-SCR gas. In situ electron paramagnetic resonance (EPR) and UV-vis spectroscopy at 250 degrees C suggest that a significant part of V4+ present during SCR conditions was oxidized to V5+ during exposure to 2% H-2 + 8% O-2. However, the distribution...

Tungsten Recovery from Spent SCR Catalyst Using Alkaline Leaching and Ion Exchange

Directory of Open Access Journals (Sweden)

Wen-Cheng Wu

2016-10-01

Full Text Available The recovery of tungsten (W from a honeycomb-type spent selective catalytic reduction (SCR catalyst using an alkaline leaching–ion exchange method was investigated. Spent SCR catalyst mainly consists of TiO2 and other oxides (6.37% W, 1.57% vanadium (V, and 2.81% silicon (Si, etc.. The ground catalyst was leached at the optimal conditions, as follows: NaOH concentration of 0.3 kg/kg of catalyst, pulp density of 3%, leaching temperature of 70 °C, particle size of −74 μm, and leaching time of 30 min. In this study, the leaching rate values of V and W under the above conditions were 87 wt %, and 91 wt %, respectively. The pregnant solution was then passed through a strong base anion exchange resin (Amberlite IRA900. At high pH conditions, the use of strong base anion exchange resin led to selective loading of divalent WO42− from the solution, because the fraction of two adjacent positively-charged sites on the IRA900 resin was higher and separate from the coexisting VO43−. The adsorbed W could then be eluted with 1 M NaCl + 0.5 M NaOH. The final concentrated W solution had 8.4 g/L of W with 98% purity. The application of this process in industry is expected to have an important impact on the recovery of W from secondary sources of these metals.

Development of Optimal Catalyst Designs and Operating Strategies for Lean NOx Reduction in Coupled LNT-SCR Systems

Energy Technology Data Exchange (ETDEWEB)

Harold, Michael [Univ. of Houston, TX (United States); Crocker, Mark [Univ. of Kentucky, Lexington, KY (United States); Balakotaiah, Vemuri [Univ. of Houston, TX (United States); Luss, Dan [Univ. of Houston, TX (United States); Choi, Jae-Soon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dearth, Mark [Ford Motor Company, Dearborn, MI (United States); McCabe, Bob [Ford Motor Company, Dearborn, MI (United States); Theis, Joe [Ford Motor Company, Dearborn, MI (United States)

2013-09-30

Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO₂) commonly referred to as NO_x, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NO_x} is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NO_x in the presence of excess O₂. Catalytic abatement measures that are effective for gasoline-fueled engines such as the precious metal containing three-way catalytic converter (TWC) cannot be used to treat O₂-laden exhaust containing NO_x. Two catalytic technologies that have emerged as effective for NO_x abatement are NO_x storage and reduction (NSR) and selective catalytic reduction (SCR). NSR is similar to TWC but requires much larger quantities of expensive precious metals and sophisticated periodic switching operation, while SCR requires an on-board source of ammonia which serves as the chemical reductant of the NO_x. The fact that NSR produces ammonia as a byproduct while SCR requires ammonia to work has led to interest in combining the two together to avoid the need for the cumbersome ammonia generation system. In this project a comprehensive study was carried out of the fundamental aspects and application feasibility of combined NSR/SCR. The project team, which included university, industry, and national lab researchers, investigated the kinetics and mechanistic features of the underlying chemistry in the lean NOx trap (LNT) wherein NSR was carried out, with particular focus on identifying the operating conditions such as temperature and catalytic properties which lead to the production of ammonia in the LNT. The performance features of SCR on both model and commercial catalysts focused on the synergy between the LNT and SCR converters in terms of utilizing the upstream-generated ammonia and

Evaluation of the first SCR-plants in Sweden; Utvaerdering av de foersta SCR-anlaeggningarna i Sverige

Energy Technology Data Exchange (ETDEWEB)

Hanell, B [Vattenfall AB, Stockholm (Sweden); and others

1996-05-01

This report presents operational experience of SCR systems at five power plants in Sweden; the diesel cogeneration plants in Linkoeping, Oskarshamn, Skultuna and Visby and the coal fired power plant in Vaesteraas. The experience represents the first years of operation of the SCR systems. The SCR-systems involved in this project achieve the following: * Uneven flue gas flow and concentration of ammonia and NO{sub x} through the SCR reactor results in lower efficiency. Hence it is important to achieve a thorough mixing of the ammonia in the flue gas in order to achieve high NO{sub x} reduction efficiencies, * Inferior control systems can cause unnecessary ammonia slip, * The diesel plants with an operating time of a couple of thousand hours have had major problems with deposits on the catalyst surface, * Guarantees regarding the lifetime of the catalyst are important. At commissioning the catalyst has to be over-dimensioned since the system has to reach the guaranteed emissions during the whole guarantee period, * There should be enough space in the reactor to install additional catalyst layers. This project verifies that additional layers need to be installed at later stages, * The mechanical construction of the SCR-reactor is important. The efficiency decreases when there is a leakage of flue gases past the reactor, * No considerable amounts of N{sub 2}O are generated by the catalyst. 21 refs, 27 figs, 47 tabs

NH3-SCR on Cu, Fe and Cu + Fe exchanged beta and SSZ-13 catalysts: Hydrothermal aging and propylene poisoning effects

International Nuclear Information System (INIS)

Wang, Aiyong; Wang, Yilin; Walter, Eric D.; Washton, Nancy M.

2017-01-01

Cu, Fe and Cu + Fe ion exchanged Beta and SSZ-13 catalysts were prepared by solution ion exchange using commercial NH 4 /Beta, and NH 4 /SSZ-13 that was prepared in-house. To study hydrothermal aging effects, Beta supported catalysts were aged hydrothermally at 700 °C and SSZ-13 supported catalysts were aged at 750 °C. In order to reveal the effects of Fe addition in the co-exchanged catalysts, these catalysts were characterized by means of powder X-ray diffraction (XRD), N 2 adsorption-desorption, electron paramagnetic resonance (EPR), 27 Al-nuclear magnetic resonance ( 27 Al-NMR) and propylene coking followed with temperature programmed reaction (TPR), and further tested with standard NH 3 -SCR with and without the presence of propylene. Collectively, the catalyst characterizations and reaction testing indicated minor beneficial effects of Fe addition in Cu,Fe/Beta, where NH 3 -SCR activity, N 2 selectivity and hydrothermal stability were all slightly improved. In contrast, Fe addition did not show apparent beneficial effects in low-temperature SCR for the Cu,Fe/SSZ-13 case. In conclusion, at elevated reaction temperatures, however, the presence of Fe indeed considerably improved NO conversion and N 2 selectivity for the hydrothermally aged Cu,Fe/SSZ-13 catalyst in the presence of propylene.

Investigation of PCDD/F emissions from mobile source diesel engines: impact of copper zeolite SCR catalysts and exhaust aftertreatment configurations.

Science.gov (United States)

Liu, Z Gerald; Wall, John C; Barge, Patrick; Dettmann, Melissa E; Ottinger, Nathan A

2011-04-01

This study investigated the impact of copper zeolite selective catalytic reduction (SCR) catalysts and exhaust aftertreatment configurations on the emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from mobile source diesel engines. Emissions of PCDD/Fs, reported as the weighted sum of 17 congeners called the toxic equivalency quotient (TEQ), were measured using a modified EPA Method 0023A in the absence and presence of exhaust aftertreatment. Engine-out emissions were measured as a reference, while aftertreatment configurations included various combinations of diesel oxidation catalyst (DOC), diesel particulate filter (DPF), Cu-zeolite SCR, Fe-zeolite SCR, ammonia oxidation catalyst (AMOX), and aqueous urea dosing. In addition, different chlorine concentrations were evaluated. Results showed that all aftertreatment configurations reduced PCDD/F emissions in comparison to the engine-out reference, consistent with reduction mechanisms such as thermal decomposition or combined trapping and hydrogenolysis reported in the literature. Similarly low PCDD/F emissions from the DOC-DPF and the DOC-DPF-SCR configurations indicated that PCDD/F reduction primarily occurred in the DOC-DPF with no noticeable contribution from either the Cu- or Fe-zeolite SCR systems. Furthermore, experiments performed with high chlorine concentration provided no evidence that chlorine content has an impact on the catalytic synthesis of PCDD/Fs for the chlorine levels investigated in this study.

Oxidation of elemental mercury by modified spent TiO2-based SCR-DeNOx catalysts in simulated coal-fired flue gas.

Science.gov (United States)

Zhao, Lingkui; Li, Caiting; Zhang, Xunan; Zeng, Guangming; Zhang, Jie; Xie, Yin'e

2016-01-01

In order to reduce the costs, the recycle of spent TiO2-based SCR-DeNOx catalysts were employed as a potential catalytic support material for elemental mercury (Hg(0)) oxidation in simulated coal-fired flue gas. The catalytic mechanism for simultaneous removal of Hg(0) and NO was also investigated. The catalysts were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) method. Results indicated that spent TiO2-based SCR-DeNOx catalyst supported Ce-Mn mixed oxides catalyst (CeMn/SCR1) was highly active for Hg(0) oxidation at low temperatures. The Ce1.00Mn/SCR1 performed the best catalytic activities, and approximately 92.80% mercury oxidation efficiency was obtained at 150 °C. The inhibition effect of NH3 on Hg(0) oxidation was confirmed in that NH3 consumed the surface oxygen. Moreover, H2O inhibited Hg(0) oxidation while SO2 had a promotional effect with the aid of O2. The XPS results illustrated that the surface oxygen was responsible for Hg(0) oxidation and NO conversion. Besides, the Hg(0) oxidation and NO conversion were thought to be aided by synergistic effect between the manganese and cerium oxides.

Alkali resistant Fe-zeolite catalysts for SCR of NO with NH3 in flue gases

DEFF Research Database (Denmark)

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

2011-01-01

. The effect of potassium doping on the acidic and redox properties of the Fe-zeolite catalysts were studied. The prepared catalysts showed high surface area and surface acidity. This is essential for increased alkali resistivity in comparison with conventional metal oxide supports like, e.g. TiO2 and ZrO2......, towards e.g. potassium salts in flue gases from biomass fired power plants. These properties allowed both undoped and potassium doped Fe-zeolite catalysts to posses high activity during the selective catalytic reduction (SCR) of NO with NH3. The extent of deactivation of the Fe-zeolite catalysts...

The black rock series supported SCR catalyst for NO x removal.

Science.gov (United States)

Xie, Bin; Luo, Hang; Tang, Qing; Du, Jun; Liu, Zuohua; Tao, Changyuan

2017-09-01

Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO 2 -TiO 2 sols and regulating its catalytic active constituents with V 2 O 5 and MoO 3 . Consequently, 90% NO removal ratio was obtained within 300-400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR), and NH 3 -temperature programmed desorption (NH 3 -TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NO x removal, including highly dispersed active components, abundant surface-adsorbed oxygen O α , well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO 2 -based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO 2 and H 2 O exceeding 85% at temperatures from 300 to 450 °C.

Strategies of Coping with Deactivation of NH3-SCR Catalysts Due to Biomass Firing

DEFF Research Database (Denmark)

Schill, Leonhard; Fehrmann, Rasmus

2018-01-01

silicates, often in the form of coal fly ash, is an industrially proven method of removing K aerosols from flue gases. Tail-end placement of the SCR unit was also reported to result in acceptable catalyst stability; however, flue-gas reheating after the flue gas desulfurization is, at present, unavoidable...... number of acid sites. This can be achieved by, e.g., using zeolites as support, replacing WO3 with heteropoly acids, and by preparing highly loaded, high surface area, very active V2O5/TiO2 catalyst using a special sol-gel method....

Speciation analysis and leaching behaviors of selected trace elements in spent SCR catalyst.

Science.gov (United States)

Dai, Zejun; Wang, Lele; Tang, Hao; Sun, Zhijun; Liu, Wei; Sun, Yi; Su, Sheng; Hu, Song; Wang, Yi; Xu, Kai; Liu, Liang; Ling, Peng; Xiang, Jun

2018-09-01

This study investigated heavy metal chemical speciation and leaching behavior from a board-type spent selective catalytic reduction (SCR) catalyst containing high concentrations of vanadium, chromium, nickel, copper, zinc, and lead. A three-step sequential extraction method, standard toxicity characteristic leaching procedure (TCLP), and leaching characteristic tests have been performed. It was found that the mobility of six heavy metals in the spent SCR catalyst was significantly different. The mobility of the six heavy metals exhibited the following order: Ni > Zn > V > Cr > As > Cu. Meanwhile, TCLP test results revealed relatively high Zn and Cr leaching rate of 83.20% and 10.35%, respectively. It was found that leaching rate was positively correlated with available contents (sum of acid soluble, reducible and oxidizable fractions). Leaching characteristics tests indicated that pH substantially affected the leaching of these heavy metals. In particular, the leaching of Cr, Ni, Cu, and Zn was positively influenced by strong acid, while V and As were easily released in the presence of strong acid and strong alkali (pH 11). In terms of kinetics, the leaching of Cr, Ni, Cu, Zn, and As within the spent catalyst was dominated by erosion and dissolution processes, which were rapid reaction processes. V was released in large amounts within 1 h, but its leaching amount sharply decreased with time due to readsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

The enhanced resistance to K deactivation of Ce/TiO2 catalyst for NH3-SCR reaction by the modification with P

Science.gov (United States)

Li, Ming-yuan; Guo, Rui-tang; Hu, Chang-xing; Sun, Peng; Pan, Wei-guo; Liu, Shu-ming; Sun, Xiao; Liu, Shuai-wei; Liu, Jian

2018-04-01

The deactivation of SCR catalyst caused by K species contained in the fly ash would suppress its DeNOx performance. In this study, it was manifested that the modification of Ce/TiO2 catalyst with P could enhance its K tolerance. To understand the promotion mechanism, the fresh and poisoned catalyst samples were subjected to the characterization techniques including BET, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFT. The results elucidated that the introduction of P species could increase the reducibility of Ce species and generate more surface chemisorbed oxygen, along with the strengthened surface acidity for NH3 adsorption. It seemed that the NH3-SCR reaction mechanism over Ce/TiO2 catalyst was a combination of L-H mechanism (reason for its good K resistance.

Methodology for Analysing the NOx-NH3 Trade-off for the Heavy-duty Automotive SCR Catalyst

DEFF Research Database (Denmark)

Åberg, Andreas; Widd, Anders; Abildskov, Jens

2017-01-01

This paper presents a methodology where pareto fronts were used to analyse how changes in the control structure for the urea dosing to the automotive SCR catalyst can improve the trade-o_ between NOx slip and NH3 slip. A previously developed simulation model was used to simulate the European...

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials expecting diesel-auto emission regulation

International Nuclear Information System (INIS)

Komatsu, Tamikuni; Tomokuni, Keizou; Yamada, Issaku

2006-01-01

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials, which does not rely on the conventional NOx-absorption-reduction-catalysts, is presented for the purpose of de-NOx of diesel-auto emissions. The established catalysts basically consist of mesoporous silica or metal-substituted mesoporous silicates for supports and platinum for active species, which is operated under lean- and rich-conditions. The new catalysts are very active at 150-200 o C and free from difficult problems of SOx-deactivation and hydrothermal ageing of the NOx-absorption-reduction catalyst. (author)

System analysis regarding NO{sub x} reduction with combined SNCR/SCR; Systemstudie avseende kombinerad NO{sub x}-reducering med SNCR/SCR

Energy Technology Data Exchange (ETDEWEB)

Niemann, Therese; Henningsson, Claes [S.E.P. Scandinavian Energy Project AB, Stockholm (Sweden); Andersson, Christer [Vattenfall Utveckling AB, Stockholm (Sweden)

2000-06-01

Systems with combined SNCR/SCR on biomass fired CFB:s have been focused on lately since they are regarded as very load flexible. Furthermore, synergy effects between the two parts are supposed to result in better performance for the combined system than for the two systems separately. The aim of this study is to investigate whether the combined SNCR/SCR matches the outlined expectations above. The plant chosen for the measurements was Brista Kraft AB. This particular plant is equipped with a CFB boiler of 122 MW{sub th}, which in turn is equipped with the deNO{sub x} system mentioned above. The measurements are made by a 'concentration gradient measurement system', developed by Vattenfall. Consequently, the study indicates that it is very useful to add a catalyst to the SNCR system, both from an environmental- and an economical point of view. However, since the full scale data for the SCR alone is missing, the results for SCR compared with combined SNCR/SCR is harder to decide. Simulations indicate that both systems produces the same emission levels, although, the SCR system may be a bit more cost effective in the long run. The synergy effect between the systems in combination is obvious. Predominantly because the NO{sub x} reduction efficiency in the SNCR zone can be increased (in this case about 10-12%) since a higher amount of ammonia can be accepted downstream of the SNCR zone. Combined systems will achieve a comparable good load independence. The reduction in the SNCR will decrease at lower loads, simultaneously as the reduction in the SCR increases. Thus, the total reduction efficiency will almost be independent of the load. In the project investigations have been made to figure out if two points injection in SNCR give more or less mol distribution of NH{sub 3}/NO quota over the catalyst crosses sectional area. The measurements indicates that two point injection may cause a more uneven distribution of stoichiometries. However, the results seems to

State Estimation for the Automotive SCR Process

DEFF Research Database (Denmark)

Zhou, Guofeng; Huusom, Jakob Kjøbsted; Jørgensen, John Bagterp

2012-01-01

Selective catalytic reduction (SCR) of NOx is a widely applied diesel engine exhaust gas aftertreatment technology. For advanced SCR process control, like model predictive control, full state information of the process is required. The ammonia coverage ratio inside the catalyst is difficult to me...

NO_x reduction and N_2O emissions in a diesel engine exhaust using Fe-zeolite and vanadium based SCR catalysts

International Nuclear Information System (INIS)

Cho, Chong Pyo; Pyo, Young Dug; Jang, Jin Young; Kim, Gang Chul; Shin, Young Jin

2017-01-01

Highlights: • NO_x reduction and N_2O emission of urea-SCR catalysts with the oxidation precatalysts were investigated. • Fe-zeolite and V-based catalysts were noticeably affected by the NO_2/NOx ratio. • Remarkable N_2O formation was observed only for the Fe-zeolite catalyst. - Abstract: Among various approaches used to comply with strict diesel engine exhaust regulations, there is increasing interest in urea based selective catalytic reduction (SCR) as a NO_x reduction technology, due to its high reduction and excellent fuel efficiencies. NO_x reduction by SCR catalysts is affected by variations in the NO_2/NO_x ratio, caused by oxidation catalysts such as the diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) installed in diesel engines. Recently, it has been reported that the greenhouse gas (GHG) variant N_2O, which is a by-product of the NO_x conversion process in the after-treatment system, will be subject to regulation. Using a real diesel engine installed with DOC and DPF, the NO_x reduction and N_2O emission performances of commonly used Fe-zeolite and V_2O_5-WO_3/TiO_2 catalysts were investigated under various operating conditions. The exhaust of the diesel engine used in this study had a NO_2/NO_x ratio of over 50% for temperatures below 400 °C due to the oxidation catalysts, while the NO_2/NO_x ratio was significantly lower for temperatures above 400 °C. Under such conditions, it was found that the Fe-zeolite and V_2O_5-WO_3/TiO_2 catalysts were noticeably affected by the NO_2/NOx ratio and exhaust temperature. Although both catalysts showed satisfactory NO conversions, the V_2O_5-WO_3/TiO_2 catalyst showed decreasing NO_2 conversion rates between 250 °C and 320 °C. The V_2O_5-WO_3/TiO_2 catalyst exhibited NH_3 slip relatively frequently because of its low NH_3 storage capacity. For the Fe-zeolite catalyst, a significant increase in the amount of generated N_2O was observed for high NO_x conversion conditions due to side

Regeneration of Pt-catalysts deactivated in municipal waste flue gas with H2/N2 and the effect of regeneration step on the SCR catalyst

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren Birk; Kustov, Arkadii

Municipal waste flue gas was previously found to deactivate the Pt-based CO oxidation catalyst severely. In the specific case studied, siloxanes were found to cause the deactivation. An on-site method for complete regeneration of the catalyst activity was found without shutdown of the flue gas...... stream, i.e. by in situ treatment of the Pt-catalyst by reductive H2-gas. However, introduction of H2 gas in the gas stream could also affect other units in the tail pipe gas cleaning system. Of special interest here, is the effect of hydrogen gas on the performance of the deNOx + SCR catalytic process...

Vanadia-based SCR Catalysts Supported on Tungstated and Sulfated Zirconia: Influence of Doping with Potassium

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Boghosian, Soghomon; Kustov, Arkadii

2007-01-01

A series of vanadium-based SCR catalysts supported on sulfated or tungstated ZrO2 were synthesized and characterized by means of N2-BET, XRD, NH3-TPD and in situ Raman spectroscopy. The effect of potassium doping on the properties of vanadia species is studied in detail. A number of catalyst...... and morphology, the surface composition and the molecular configuration of the dispersed vanadates. It was observed that poisoning with potassium had a negligible effect on the surface vanadate species (especially the V=O stretching frequency observed by in situ Raman spectroscopy) if supported on the sulfated...... the observed decrease in V=O stretching frequency and the higher proportion of dimers and higher polymers through coordination between K+ and two neighbouring V=O. The results suggest an increased resistance towards potassium doping for the vanadia-based catalysts supported on sulfated zirconia....

STUDY OF THE EFFECT OF CHLORINE ADDITION ON MERCURY OXIDATION BY SCR CATALYST UNDER SIMULATED SUBBITUMINOUS COAL FLUE GAS

Science.gov (United States)

An entrained flow reactor is used to study the effect of addition of chlorine-containing species on the oxidation of elemental mercury (Hgo)by a selective catalytic reduction (SCR) catalyst in simulated subbituminous coal combustion flue gas. The combustion flue gas was doped wit...

Influence of reaction products of K-getter fuel additives on commercial vanadia-based SCR catalysts Part II. Simultaneous addition of KCl, Ca(OH)(2), H3PO4 and H2SO4 in a hot flue gas at a SCR pilot-scale setup

DEFF Research Database (Denmark)

Castellino, Francesco; Jensen, Anker Degn; Johnsson, Jan Erik

2009-01-01

A commercial V2O5-WO3-TiO2 corrugated-type SCR monolith has been exposed for 1000 h in a pilot-scale setup to a flue gas doped with KCl, Ca(OH)(2), H3PO4 and H2SO4 by spraying a water solution of the components into the hot flue gas. The mixture composition has been adjusted in order to have P...... surface and did not proceed at the fast rates known for KCl. This fact indicates that binding K in P-K-Ca compounds is an effective way to reduce the negative influence of alkali metals on the lifetime of the vanadia-based SCR catalysts. On the other hand, P-deposition was favoured by the formation...

Improved Automotive NO (x) Aftertreatment System: Metal Ammine Complexes as NH3 Source for SCR Using Fe-Containing Zeolite Catalysts

DEFF Research Database (Denmark)

Johannessen, Tue; Schmidt, Henning; Frey, Anne Mette

2009-01-01

Ammonia storage is a challenge in the selective catalytic reduction of NO (x) in vehicles. We propose a new system, based on metal ammines as the ammonia source. In combination with iron containing zeolites as the SCR catalyst it should be possible to obtain a low temperature system for NO (x...

Effect of the sol-gel conditions on the morphology and SCR performance of electrospun V-W-TiO2 catalysts

DEFF Research Database (Denmark)

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

2018-01-01

V-W-TiO2 catalysts are prepared as nanofibers for the removal of the NOx in exhausts via the NH3 Selective Catalytic Reduction (SCR) method. By combining electrospinning and soft chemistry, materials are processed as nanofibers with the catalytic components (e. g. V2O5-WO3) incorporated as dopant...

SCR at bio fuels combustion - phase 2. Measures to extend catalyst life time; SCR vid biobraensleeldning - etapp 2. Aatgaerder foer att foerlaenga katalysatorns livslaengd

Energy Technology Data Exchange (ETDEWEB)

Andersson, Christer; Bodin, Henrik; Sahlqvist, Aasa [Vattenfall Utveckling AB, Aelvkarleby (Sweden); Khodayari, Raziyeh; Odenbrand, Ingemar [Lund Univ. (Sweden). Dept. of Chemical Engineering II

2000-07-01

In this project phase, the deactivation of catalysts during combustion of bio fuels, and different methods of regeneration have been investigated. The overall purpose is to improve the economic and technical possibilities to use SCR at bio fuels combustion. The two different methods for regeneration are washing with water and so called sulphation (treatment with sulphur dioxide). The results from wood fired FB-boilers show that the catalyst lose 25% (average) of the relative activity during a normal heat production season. The tendency is that a boiler with short residence time between final combustion and catalyst and/or high flame temperatures gives a faster deactivation. Such unfavourable conditions arise in FB-boilers with a large part of the combustion in freeboard/cyclone. The alkali content of the fuel (wood fuel) is of minor importance for the deactivation rate compared with the combustion conditions. The flue gas temperature within the interval 250 - 375 deg C is not an important parameter for the deactivation in the time interval 3 000 - 6 000 h. The 'new' honeycomb catalysts that were tested during phase two, BiotypA-C, evidently show different deactivation trends. The highly active BiotypC e.g. increases its activity during the first thousand hours. Calculations indicate that BiotypC at 315 deg C requires the smallest volume of catalyst over ten years of operation in order to maintain given performance. Practical consequences for downstream equipment also need to be carefully checked. Sulphation with SO{sub 2} works in the laboratory as a regeneration method for all of the tested samples. The sulphatised samples deactivation are almost comparable to a fresh sample when exposed to flue gas. About 80 % of the lost activity can be regained only by using sulphation. Plate-type catalysts gets a somewhat lower increase in activity compared to honeycomb-types, probably related to chemical rather than geometric design. High SO{sub 2}-concentration

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.)

Deactivation of SCR Catalysts by Additives

DEFF Research Database (Denmark)

Castellino, Francesco

2008-01-01

forskellige opløsninger af K3PO4. Resultaterne viste, at hvis K bindes i K-P saltforbindelser ville dette ikke reducere hastigheden af katalysatorens deaktivering. Regenereringstest udført i laboratoriet på katalysatorplader viste, at regenerering af de eksponerede katalysatorer var muligt ved at vaske demmed...... 0.5Mvandig opløsning af H2SO4. Somdet sidste blev en kommerciel V2O5-WO3-TiO2 SCR monolit eksponer et i 1000 timer for røggas tilsat en vandig opløsning af KCl, Ca(OH)2, H3PO4 og H2SO4 i en pilotopstilling. Blandingens sammensætning blev justeret med henblik på at have et P/K og P/Ca forhold på...... for KCl eller K3PO4. Dette faktum indikerer at kemisk binding af K i P-K-Ca-forbindelser er en effektiv måde at reducere den negative indflydelse på levetiden af vanadium baserede SCR katalysatorer hidrørende fra alkalimetaller. På den anden side blev fosforafsætning og -belægningsdannelse favoriseret ved...

BASF catalysts for the removal of NO{sub x} and dioxin in various applications

Energy Technology Data Exchange (ETDEWEB)

Morsbach, B; Odermatt, P; Spahl, R [BASF AG, Ludwigshafen (Germany)

1997-12-31

The aim of this paper is to give an overview on the catalytic removal of NO{sub x} and dioxin. In the first part of this paper possible locations of the SCR (Selective Catalytic Reduction) units will be presented. The second part will concentrate on the mathematical models of the SCR-reaction with titanium-tungsten-vanadium catalysts. (author)

BASF catalysts for the removal of NO{sub x} and dioxin in various applications

Energy Technology Data Exchange (ETDEWEB)

Morsbach, B.; Odermatt, P.; Spahl, R. [BASF AG, Ludwigshafen (Germany)

1996-12-31

The aim of this paper is to give an overview on the catalytic removal of NO{sub x} and dioxin. In the first part of this paper possible locations of the SCR (Selective Catalytic Reduction) units will be presented. The second part will concentrate on the mathematical models of the SCR-reaction with titanium-tungsten-vanadium catalysts. (author)

OXIDATION OF MERCURY ACROSS SCR CATALYSTS IN COAL-FIRED POWER PLANTS BURNING LOW RANK FUELS

Energy Technology Data Exchange (ETDEWEB)

Constance Senior; Temi Linjewile

2003-07-25

This is the first Quarterly Technical Report for DOE Cooperative Agreement No: DE-FC26-03NT41728. The objective of this program is to measure the oxidation of mercury in flue gas across SCR catalyst in a coal-fired power plant burning low rank fuels using a slipstream reactor containing multiple commercial catalysts in parallel. The Electric Power Research Institute (EPRI) and Ceramics GmbH are providing co-funding for this program. This program contains multiple tasks and good progress is being made on all fronts. During this quarter, analysis of the coal, ash and mercury speciation data from the first test series was completed. Good agreement was shown between different methods of measuring mercury in the flue gas: Ontario Hydro, semi-continuous emission monitor (SCEM) and coal composition. There was a loss of total mercury across the commercial catalysts, but not across the blank monolith. The blank monolith showed no oxidation. The data from the first test series show the same trend in mercury oxidation as a function of space velocity that has been seen elsewhere. At space velocities in the range of 6,000-7,000 hr{sup -1} the blank monolith did not show any mercury oxidation, with or without ammonia present. Two of the commercial catalysts clearly showed an effect of ammonia. Two other commercial catalysts showed an effect of ammonia, although the error bars for the no-ammonia case are large. A test plan was written for the second test series and is being reviewed.

Alternative alkali resistant deNOx catalysts

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes

2012-01-01

by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH3-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V2O5-WO3/TiO2 catalyst. After potassium poisoning (100......Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared......–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V2O5-WO3/TiO2 catalyst. Furthermore, Cu/MOR and Nano-V2O5/Sul-TiO2 catalysts showed 8–16 times higher SCR activities than the conventional even after high...

Effects of NOX Storage Component on Ammonia Formation in TWC for Passive SCR NOX Control in Lean Gasoline Engines

Energy Technology Data Exchange (ETDEWEB)

Prikhodko, Vitaly Y. [ORNL; Pihl, Josh A. [ORNL; Toops, Todd J. [ORNL; Parks, II, James E. [ORNL

2018-04-01

A prototype three-way catalyst (TWC) with NOX storage component was evaluated for ammonia (NH3) generation on a 2.0-liter BMW lean burn gasoline direct injection engine as a component in a passive ammonia selective catalytic reduction (SCR) system. The passive NH3 SCR system is a potential approach for controlling nitrogen oxides (NOX) emissions from lean burn gasoline engines. In this system, NH3 is generated over a close-coupled TWC during periodic slightly-rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. Adding a NOX storage component to a TWC provides two benefits in the context of a passive SCR system: (1) enabling longer lean operation by storing NOX upstream and preserving NH3 inventory on the downstream SCR catalyst; and (2) increasing the quantity and rate of NH3 production during rich operation. Since the fuel penalty associated with passive SCR NOX control depends on the fraction of time that the engine is running rich rather than lean, both benefits (longer lean times and shorter rich times achieved via improved NH3 production) will decrease the passive SCR fuel penalty. However, these benefits are primarily realized at low to moderate temperatures (300-500 °C), where the NOX storage component is able to store NOX, with little to no benefit at higher temperatures (>500 °C), where NOX storage is no longer effective. This study discusses engine parameters and control strategies affecting the NH3 generation over a TWC with NOX storage component.

The enhancement of CuO modified V2O5-WO3/TiO2 based SCR catalyst for Hg° oxidation in simulated flue gas

Science.gov (United States)

Chen, Chuanmin; Jia, Wenbo; Liu, Songtao; Cao, Yue

2018-04-01

CuO modified V2O5-WO3/TiO2 based SCR catalysts prepared by improved impregnation method were investigated to evaluate the catalytic activity for elemental mercury (Hg°) oxidation in simulated flue gas at 150-400 °C. Nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. It was found that V0.8WTi-Cu3 catalyst exhibited the superior Hg° oxidation activity and wide operating temperature window at the gas hourly space velocity (GHSV) of 3 × 105 h-1. The BET and XRD results showed that CuO was well loaded and highly dispersed on the catalysts surface. The XPS results suggested that the addition of CuO generated abundant chemisorbed oxygen, which was due to the synergistic effect between CuO and V2O5. The existence of the redox cycle of V4+ + Cu2+ ↔ V5+ + Cu+ in V0.8WTi-Cu3 catalyst enhanced Hg° oxidation activity. The effects of flue gas components (O2, NO, SO2 and H2O) on Hg° oxidation over V0.8WTi-Cu3 catalyst were also explored. Moreover, the co-presence of NO and NH3 remarkably inhibited Hg° oxidation, which was due to the competitive adsorption and reduction effect of NH3 at SCR condition. Fortunately, this inhibiting effect was gradually scavenged with the decrease of GHSV. The mechanism of Hg° oxidation was also investigated.

The effect of the gas composition on hydrogen-assisted NH3-SCR over Ag/Al2O3

DEFF Research Database (Denmark)

Tamm, Stefanie; Fogel, Sebastian; Gabrielsson, Pär

2013-01-01

In addition to high activity in hydrocarbon-SCR, Ag/Al2O3 catalysts show excellent activity for NOx reduction for H2-assisted NH3-SCR already at 200°C. Here, we study the influence of different gas compositions on the activity of a pre-sulfated 6wt% Ag/Al2O3 catalyst for NOx reduction, and oxidat...

On the Effect of Preparation Methods of PdCe-MOR Catalysts as NOx CH4-SCR System for Natural Gas Vehicles Application

Directory of Open Access Journals (Sweden)

Acácio Nobre Mendes

2015-10-01

Full Text Available In the present work, the effect of several parameters involved in the preparation of PdCe-HMOR catalysts active for NOx selective catalytic reduction with methane (NOx CH4-SCR was studied. Results show that the catalytic performance of Pd-HMOR is better when palladium is introduced by ion-exchange, namely at room temperature. It was also shown that Pd loading does not influence the formation of cerium species, namely surface Ce4+ (CeO2 species and CeO2 species in interaction with Pd. However, when Ce is introduced before Pd, more surface CeO2 species are stabilized in the support and less CeO2 become in interaction with Pd, which results in a worse NOx CH4-SCR catalytic performance.

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.

Fabrication of doped Titania (TiO2) nanofibers to serve as catalysts in NH₃-Selective CatalyticReduction (SCR)

DEFF Research Database (Denmark)

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

2016-01-01

conversion efficiencies are obtained andassociated with the unique features deriving from the synergism among the doping approach, the nanoscaleconfinement, and the nano-fibrous texture. A novel concept of self-supported, lightweight and ultra-compactdesign SCR reactor is defined....... of either one or moredimensions into the nanoscale level. Among others the large surface-to-volume ratio is a feature that greatlyincreases the reactivity of the nanomaterials towards gaseous species when compared with the non-nanodimensional materials. With this regards, catalysis is one of those...... applications that unquestionable benefitsfrom this novel feature. In addition, when nanofibers (1D nanostructure) are used as catalysts, the furtheradvantage of a self-supported wide open and well-interconnected porous structure is achieved.Herein we demonstrate nanofibers as catalysts for the removal...

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-08-01

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

Evaluation of air jet erosion profiles in metal mesh supported SCR plate catalyst based on glass fiber concentrations

Science.gov (United States)

Rajath, S.; Nandakishora, Y.; Siddaraju, C.; Roy, Sukumar

2018-04-01

This paper explains the evaluation of erosion profiles in metal mesh supported SCR plate catalyst structures in which the glass fibers concentration in the catalyst material is considered as prime factor for erosion resistance and mechanical strength. The samples are prepared and tested at the specified and constant conditions like velocity as 30m/s, sand flow rate as 2g/min, average particle diameter 300 µm and all these samples were tested at different angles at impact preferably 15°,30°,45°,60°,75°,and 90° as per ASTM G76 standards. Say, if 5% glass fibers are present in catalyst material, then erosion resistance increases, but the density of glass fibers is very less because each glass fiber is approximately 20 microns in diameter and weight of individual is negligible. The composition in which 2% fiber is present has slightly higher erosion comparatively, but 3% glass fibers or more foreign inclusion like excessive binders can be eliminated that contributes much for the conversion of NOx. So 2% -3% glass fibers are preferred and optimized based on NOx conversion and erosion resistance property.

Bromine based mercury abatement in waste and coal combustion. Mercury retention in the catalyst bed of a tail-end-SCR

Energy Technology Data Exchange (ETDEWEB)

Vosteen, Bernhard W. [Vosteen Consulting GmbH, Koeln (Germany); Kanefke, Rico; Beyer, Joachim; Bonkhofer, Theodor Gerhard [CURRENTA GmbH und Co. OHG, Leverkusen (Germany); Ullrich, Rick [WastePro Engineering Inc., Kennett Square, PA (United States)

2008-07-01

Observations and testing at a CURRENTA waste incineration plant and several coal fired power plants has derived the following aspects of mercury behavior in the plant's waste heat boiler and its gas cleaning train: - Hg{sub met} is oxidized to Hg{sub ion} most readily by bromine, and also by chlorine, - sulfur (SO{sub 2}) inhibit the Hg{sub met} chlorination but not the Hg{sub met} bromination, - Hg{sub met} passes through scrubbers and is adsorbed onto the catalyst bed of a tail-end SCR, slowly oxidized and finally elutes off as Hg{sub ion}, - sulfur (SO{sub 2}) impacts the reduction of molecular halogens in different ways; SO{sub 2} reduces Cl{sub 2} at elevated temperatures (boiler range), but reduces Br{sub 2} only at low temperatures (scrubber range) The operational tests and studies performed in the spring and summer of 2000 at this plant led to some specific knowledge about Hg{sub met} adsorption and also Hg{sub ion} desorption at the catalyst bed of a tail-end SCR. This knowledge, which was at that time in many respects novel, has provided more insight into the mercury oxidation behaviour. Today, process options derived from this knowledge could be implemented in hazardous waste incineration plants and also municipal solid waste incineration plants, to achieve complete mercury halogenation in the boiler flue gas, ahead of the scrubber system, at any time. This might prevent penetration of metallic mercury to the tail-end SCR and avoid the corresponding long time mercury elution. For effective prevention to be achieved in practice, it is strongly recommended to also install a continuously measuring (possibly uncalibrated) AAS mercury monitor for immediate detection of any unexpected Hg{sub met} breakthrough, for example caused by ''hidden mercury'' in the waste feed, and to initiate the rapid (preferably automized) injection of some bromine compound before even more mercury is transferred into the tail-end SCR, stored there as Hg

Iron loading effects in Fe/SSZ-13 NH3-SCR catalysts: nature of the Fe-ions and structure-function relationships

Energy Technology Data Exchange (ETDEWEB)

Gao, Feng; Zheng, Yang; Kukkadapu, Ravi K.; Wang, Yilin; Walter, Eric D.; Schwenzer, Birgit; Szanyi, Janos; Peden, Charles HF

2016-05-06

Using a traditional aqueous solution ion-exchange method under a protecting atmosphere of N2, a series of Fe/SSZ-13 catalysts with various Fe loadings were synthesized. UV-Vis, EPR and Mössbauer spectroscopies, coupled with temperature programmed reduction and desorption techniques, were used to probe the nature of the Fe sites. The major monomeric and dimeric Fe species are extra-framework [Fe(OH)2]+ and [HO-Fe-O-Fe-OH]2+. Larger oligomers with unknown nuclearity, poorly crystallized Fe2O3 particles, together with isolated Fe2+ ions, are minor Fe-containing moieties. Reaction rate and Fe loading correlations suggest that isolated Fe3+ ions are the active sites for standard SCR while the dimeric sites are the active centers for NO oxidation. NH3 oxidation, on the other hand, is catalyzed by sites with higher nuclearity. A low-temperature standard SCR reaction network is proposed that includes redox cycling of both monomeric and dimeric Fe species, for SCR and NO2 generation, respectively. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Program for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

Vanadia supported on zeolites for SCR of NO by ammonia

DEFF Research Database (Denmark)

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

2010-01-01

, acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali-containing flue gases from, e.g. biomass fired...

Reactivity of Surface Nitrates in H2-Assisted SCR of NOx Over Ag/Al2O3 Catalyst

DEFF Research Database (Denmark)

Sadokhina, N. A.; Doronkin, Dmitry E.; Baeva, G. N.

2013-01-01

The role of nitrate ad-species in H2-assisted SCR over Ag/Al2O3 was compared in NH3-SCR and n-C6H14-SCR processes. It was found that nitrates could be reduced by NH3 or n-C6H14 at similar rates with H2 co-feeding which indicates a common rate-limiting step. However, contributions of surface nitrate...... reduction to the overall NH3-SCR or n-C6H14-SCR are different as revealed by comparing the rates of nitrate reduction with the rates of steady-state processes. The rate of the steady-state n-C6H14-SCR is virtually identical to the rate of surface nitrate reduction suggesting a significant contribution...... of the surface nitrates reduction to the overall n-C6H14-SCR process. On the other hand, the steady-state rate of NH3-SCR is by ~15 times higher, which indicates that the reduction of surface nitrates plays a marginal role in the overall NH3-SCR....

Demonstration of Selective Catalytic Reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers. Technical progress report, first and second quarters 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

The objective of this project is to demonstrate and evaluate commercially available Selective Catalytic Reduction (SCR) catalysts from U.S., Japanese and European catalyst suppliers on a high-sulfur U.S. coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO{sub x}) control technology that involve injecting ammonia into the flue gas generated from coal combustion in a boiler. The flue gas containing ammonia is then passed through a reactor that contains a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO{sub x} to form nitrogen and water vapor. Although SCR is widely practiced in Japan and Europe on gas-, oil-, and low-sulfur coal-fired boilers, there are several technical uncertainties associated with applying SCR to U.S. coals. These uncertainties include: (1) potential catalyst deactivation due to poisoning by trace metal species present in U.S. coals that are not present in other fuels; (2) performance of the technology and effects on the balance-of-plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}; and (3) performance of a wide variety of SCR catalyst compositions, geometries and methods of manufacture under typical high-sulfur coal-fired utility operating conditions. These uncertainties are being explored by operating a series of small-scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur U.S. coal. The project is being conducted in the following three phases: permitting, environmental monitoring plan and preliminary engineering; detailed design engineering and construction; and operation, testing, disposition and final report. The project was in the operation and testing phase during this reporting period. Accomplishments for this period are described.

Deactivation of vanadia-based commercial SCR catalysts by polyphosphoric acids

DEFF Research Database (Denmark)

Castellino, Francesco; Rasmussen, Søren Birk; Jensen, Anker Degn

2008-01-01

Commercial vanadia-based SCR monoliths have been exposed to flue gases in a pilot-scale Setup into which phosphoric acid has been added and the deactivation has been followed during the exposure time. Separate measurements by SMPS showed that the phosphoric acid formed polyphosphoric acid aerosols...

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....

The development and application of SCR denitrification technology in power plant

Science.gov (United States)

Wu, Junnan

2017-12-01

In recent decades, the emission of the nitrogen oxides (NOX) has been increasing with the years of the thermal power plant. The environment pollution caused by the emission of quantities of nitrogen oxides became more and more serious, so people now put more emphasis on the control of the emission of the nitrogen oxides. Especially, our country and the society are paying much more attention to the environment protection and the environment problems cannot be neglected. In this paper, we introduced the related research background of the technology of SCR denitrification which was as the symbol of the technology of the catalytic denitrification and discussed the reaction principles of the SCR denitrification and frequently used catalysts, the process of the technology, and the configuration. In the end, we pointed the way of the future research of the technology of the SCR denitrification.

Multiphase catalysts for selective reduction of NOx with hydrocarbons

International Nuclear Information System (INIS)

Maisuls, S.E.

2000-01-01

Among the existing proposed solutions to reduce emission of NOx there is a promising alternative, the so-called (HC-SCR) selective catalytic reduction of NOx using hydrocarbons as reductant. This thesis is part of a worldwide effort devoted to gain knowledge on the selective catalytic reduction of NOx with hydrocarbons with the final goal to contribute to the development of suitable catalysts for the above mentioned process. Chapter 2 describes the details of the experimental set-up and of the analytical methods employed. Among the catalyst for HC-SCR, Co-based catalyst are known to be active and selective, thus, a study on a series of Co-based catalysts, supported on zeolites, was undertaken and the results are presented in Chapter 3. Correlation between catalytic characteristics and kinetic results are employed to understand the working catalyst and this is used as a basis for catalyst optimization. With the intention to prepare a multi-functional catalyst that will preserve the desired characteristics of the individual components, minimizing their negative aspects, catalysts based on Co-Pt, supported on ZSM-5, were investigated. In Chapter 4 the results of this study are discussed. A bimetallic Co-Pt/ZSM-5 catalysts with low Pt contents (0.1 wt %) showed a synergistic effect by combining high stability and activity of Pt catalysts with the high N2 selectivity of Co catalysts. Furthermore, it was found to be sulfur- and water-tolerant. Its positive qualities brought us to study the mechanism that takes place over this catalyst during HC-SCR. The results of an in-situ i.r mechanistic study over this catalyst is reported in Chapter 5. From the results presented in Chapter 5 a mechanism operating over the Co-Pt/ZSM-5 catalyst is proposed. The modification of Co catalyst with Pt improved the catalysts. However, further improvement was found to be hindered by high selectivity to N2O. Since Rh catalysts are generally less selective to N2O, the modification of Co

Characterization of Co and Fe-MCM-56 catalysts for NH3-SCR and N2O decomposition: An in situ FTIR study

Science.gov (United States)

Grzybek, Justyna; Gil, Barbara; Roth, Wieslaw J.; Skoczek, Monika; Kowalczyk, Andrzej; Chmielarz, Lucjan

2018-05-01

Two-step preparation of iron and cobalt-containing MCM-56 zeolites has been undertaken to evaluate the influence of their physicochemical properties in the selective catalytic reduction (NH3-SCR or DeNOx) of NO using NH3 as a reductant. Zeolites were prepared by the selective leaching of the framework cations by concentrated HNO3 solution and NH4F/HF mixture and consecutively, introduction of Co and Fe heteroatoms, in quantities below 1 wt%. Further calcination allowed to obtain highly dispersed active species. Their evaluation and speciation was realized by adsorption of pyridine and NO, followed by FTIR spectroscopy. Both Fe-MCM-56 zeolites showed excellent activities (maximum NO conversion 92%) with high selectivity to dinitrogen (above 99%) in the high temperature NH3-SCR process. High catalytic activity of Fe-MCM-56 zeolites was assigned to the formation of stable nitrates, delivering NO to react with NH3 at higher temperatures and suppressing the direct NO oxidation. It was found that more nitrates was formed in Fe-MCM-56 (HNO3) than in Fe-MCM-56 (HF/NH4F) and that could compensate for the lower Fe loading, resulting in very similar catalytic activity of both catalysts. At the same time both Co-and Fe-MCM-56 zeolites were moderately active in direct N2O decomposition, with maximum N2O conversion not higher than 80% and activity window starting at 500 °C. This phenomenon was expected since both types of catalysts contained well dispersed active centers, not beneficial for this reaction.

Demonstration of SCR technology for the control of NOx emissions from high-sulfur coal-fired utility boilers

Energy Technology Data Exchange (ETDEWEB)

Hinton, W.S. [W.S. Hinton and Associates, Cantonment, FL (United States); Maxwell, J.D.; Healy, E.C.; Hardman, R.R. [Southern Company Services, Inc., Birmingham, AL (United States); Baldwin, A.L. [Dept. of Energy, Pittsburgh, PA (United States)

1997-12-31

This paper describes the completed Innovative Clean Coal Technology project which demonstrated SCR technology for reduction of flue gas NO{sub x} emissions from a utility boiler burning US high-sulfur coal. The project was sponsored by the US Department of Energy, managed and co-funded by Southern Company Services, Inc. on behalf of the Southern Company, and also co-funded by the Electric Power Research Institute and Ontario Hydro. The project was located at Gulf Power Company`s Plant Crist Unit 5 (a 75 MW tangentially-fired boiler burning US coals that had a sulfur content ranging from 2.5--2.9%), near Pensacola, Florida. The test program was conducted for approximately two years to evaluate catalyst deactivation and other SCR operational effects. The SCR test facility had nine reactors: three 2.5 MW (5,000 scfm), and operated on low-dust flue gas. The reactors operated in parallel with commercially available SCR catalysts obtained from suppliers throughout the world. Long-term performance testing began in July 1993 and was completed in July 1995. A brief test facility description and the results of the project are presented in this paper.

Catalyst for reduction of nitrogen oxides

Science.gov (United States)

Ott, Kevin C.

2010-04-06

A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

Surface Species and Metal Oxidation State during H2-Assisted NH3-SCR of NOx over Alumina-Supported Silver and Indium

Directory of Open Access Journals (Sweden)

Linda Ström

2018-01-01

Full Text Available Alumina-supported silver and indium catalysts are investigated for the hydrogen-assisted selective catalytic reduction (SCR of NOx with ammonia. Particularly, we focus on the active phase of the catalyst and the formation of surface species, as a function of the gas environment. Diffuse reflectance ultraviolet-visible (UV-vis spectroscopy was used to follow the oxidation state of the silver and indium phases, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS was used to elucidate the formation of surface species during SCR conditions. In addition, the NOx reduction efficiency of the materials was evaluated using H2-assisted NH3-SCR. The DRIFTS results show that the Ag/Al2O3 sample forms NO-containing surface species during SCR conditions to a higher extent compared to the In/Al2O3 sample. The silver sample also appears to be more reduced by H2 than the indium sample, as revealed by UV-vis spectroscopic experiments. Addition of H2, however, may promote the formation of highly dispersed In2O3 clusters, which previously have been suggested to be important for the SCR reaction. The affinity to adsorb NH3 is confirmed by both temperature programmed desorption (NH3-TPD and in situ DRIFTS to be higher for the In/Al2O3 sample compared to Ag/Al2O3. The strong adsorption of NH3 may inhibit (self-poison the NH3 activation, thereby hindering further reaction over this catalyst, which is also shown by the lower SCR activity compared to Ag/Al2O3.

Special requirements for the fluid mechanical design of hard coal-fired SCR retrofit units

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

The system design of high-dust SCR units for retrofits is a challenge that is to be mastered in order to meet the fluid mechanical requirements. Retrofitting power plants with NOx control technologies is a cost-intensive adventure that many utilities are undertaking. Except for a few recent new boiler installations, SCR installations must be considered as retrofit projects. In most cases the limitation of space on site entails unfavorable conditions that do not allow appropriate upstream conditions for SCR catalysts. To comply with the requirements of high performance DeNOx systems and to lower the investment costs for retrofit units, several technical solutions and concepts for the reactor layout, for NOx and dust distribution, for flow stabilization in diffusers, and advanced ammonia injection systems are explained in this paper. Balcke-Duerr offers customer-tailored solutions for flow optimization, which are evaluated by model studies. Physical flow and dust model tests in an appropriate scale provide flexibility to test various engineering concepts. The experience of Balcke-Duerr is based on continuous research and development activities over the last 25 years and more than 350 executed projects for gas flow optimization applications. The success of these installations is a direct result of the key decisions based on the improved fluid mechanical design and proper system integration. This paper also identifies the sensible design particularities and solutions that have two be considered in the fluid mechanical design of high-dust SCR retrofit units. This article demonstrates that the layout of SCR units must be carefully reviewed in order to meet the performance requirements and to avoid problems, i.e. wear, catalyst plugging and ammonia slip. 9 refs., 18 figs.

Innovative Clean Coal Technology (ICCT): Demonstration of selective catalytic reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers. Technical progress report, third and fourth quarters 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

The objective of this project is to demonstrate and evaluate commercially available selective catalytic reduction (SCR) catalysts from U.S., Japanese, and European catalyst suppliers on a high-sulfur U.S. Coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO{sub x}) control technology that involves injecting ammonia into the flue gas generated from coal combustion in an electric utility boiler. The flue gas containing ammonia is then passed through a reactor that contains a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO{sub x} to form nitrogen and water vapor. Although SCR is widely practiced in Japan and European gas-, oil-, and low-sulfur coal-fired boilers, there are several technical uncertainties associated with applying SCR to U.S. coals. These uncertainties include: (1) potential catalyst deactivation due to poisoning by trace metal species present in U.S. coals that are not present in other fuels; (2) performance of the technology and effects on the balance-of-plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}; performance of a wide variety of SCR catalyst compositions, geometries, and methods of manufacture under typical high-sulfur coal-fired utility operating conditions. These uncertainties are being explored by operating a series of small- scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur U.S. coal. The demonstration is being performed at Gulf Power Company`s Plant Crist Unit No. 5 (75 MW capacity) near Pensacola, Florida. The project is funded by the U.S. Department of Energy (DOE), Southern Company Services, Inc. (SCS on behalf of the entire Southern electric system), the Electric Power Research Institute (EPRI), and Ontario Hydro. SCS is the participant responsible for managing al aspects of this project. 1 ref., 69 figs., 45 tabs.

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.

LPV gain-scheduled control of SCR aftertreatment systems

Science.gov (United States)

Meisami-Azad, Mona; Mohammadpour, Javad; Grigoriadis, Karolos M.; Harold, Michael P.; Franchek, Matthew A.

2012-01-01

Hydrocarbons, carbon monoxide and some of other polluting emissions produced by diesel engines are usually lower than those produced by gasoline engines. While great strides have been made in the exhaust aftertreatment of vehicular pollutants, the elimination of nitrogen oxide (NO x ) from diesel vehicles is still a challenge. The primary reason is that diesel combustion is a fuel-lean process, and hence there is significant unreacted oxygen in the exhaust. Selective catalytic reduction (SCR) is a well-developed technology for power plants and has been recently employed for reducing NO x emissions from automotive sources and in particular, heavy-duty diesel engines. In this article, we develop a linear parameter-varying (LPV) feedforward/feedback control design method for the SCR aftertreatment system to decrease NO x emissions while keeping ammonia slippage to a desired low level downstream the catalyst. The performance of the closed-loop system obtained from the interconnection of the SCR system and the output feedback LPV control strategy is then compared with other control design methods including sliding mode, and observer-based static state-feedback parameter-varying control. To reduce the computational complexity involved in the control design process, the number of LPV parameters in the developed quasi-LPV (qLPV) model is reduced by applying the principal component analysis technique. An LPV feedback/feedforward controller is then designed for the qLPV model with reduced number of scheduling parameters. The designed full-order controller is further simplified to a first-order transfer function with a parameter-varying gain and pole. Finally, simulation results using both a low-order model and a high-fidelity and high-order model of SCR reactions in GT-POWER interfaced with MATLAB/SIMULINK illustrate the high NO x conversion efficiency of the closed-loop SCR system using the proposed parameter-varying control law.

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.

EVALUATION OF MERCURY EMISSIONS FROM COAL-FIRED FACILITIES WITH SCR AND FGD SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; S.C. Tseng; J. E. Locke

2004-10-31

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP) - wet flue gas desulfurization (FGD) combination or a spray dyer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on Hg speciation and the efficacy of different FGD technologies for Hg capture. This document, the second in a series of topical reports, describes the results and analysis of mercury sampling performed on a 330 MW unit burning a bituminous coal containing 1.0% sulfur. The unit is equipped with a SCR system for NOx control and a spray dryer absorber for SO{sub 2} control followed by a baghouse unit for particulate emissions control. Four sampling tests were performed in March 2003. Flue gas mercury speciation and concentrations were determined at the SCR inlet, air heater outlet (ESP inlet), and at the stack (FGD outlet) using the Ontario Hydro method. Process stream samples for a mercury balance were collected to coincide with the flue gas measurements. Due to mechanical problems with the boiler feed water pumps, the actual gross output was between 195 and 221 MW during the tests. The results showed that the SCR/air heater combination oxidized nearly 95% of the elemental mercury. Mercury removal, on a

Pore design of pelletised VOX/ZrO2-SO4/Sepiolite composite catalysts

DEFF Research Database (Denmark)

Rasmussen, Søren Birk; Due-Hansen, Johannes; Yates, M.

2010-01-01

The NH3-SCR activities of a series of extruded and calcined VOX/ZrO2-SO4 - sepiolite catalysts were determined. The pore structures were heavily influenced by the clay content with macropore sizes ranging from 50 to >1000 nm. Mechanical strength and SCR activity measurements suggested that 25% w/....../w sepiolite is the optimal catalyst composition....

Ti and Si doping as a way to increase low temperature activity of sulfated Ag/Al2O3 in H2-assisted NH3-SCR of NOx

DEFF Research Database (Denmark)

Doronkin, Dmitry E.; Fogel, Sebastian; Gabrielsson, Pär

2013-01-01

Ag/Al2O3 catalysts modified by Si, Ti, Mg and W were studied to obtain higher NOx SCR activity and potentially also higher SO2 resistance than the pure silver-based catalyst for automotive applications. Addition of Ti or Si to the alumina support leads to a better NOx removal at low temperature i......-TPR) and temperature-programmed desorption of ammonia (NH3-TPD). The obtained results suggest a better silver dispersion and better regeneration capability in the case of Ti- and Si-modified Ag/Al2O3 catalysts........e. reduces the SCR onset temperature by about 10°C under the applied conditions. However, it does not increase the SO2 resistance. The catalysts and the supports have been characterized by BET, conventional and synchrotron XRD, X-ray absorption spectroscopy during temperature-programmed reduction (XAS......Ag/Al2O3 catalysts modified by Si, Ti, Mg and W were studied to obtain higher NOx SCR activity and potentially also higher SO2 resistance than the pure silver-based catalyst for automotive applications. Addition of Ti or Si to the alumina support leads to a better NOx removal at low temperature i...

Catalyst and method for reduction of nitrogen oxides

Science.gov (United States)

Ott, Kevin C [Los Alamos, NM

2008-05-27

A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

Alternative catalysts and technologies for NOx removal from biomass- and wastefired plants

DEFF Research Database (Denmark)

Schill, Leonhard

removed with the selective catalytic reduction (SCR) using a vanadia-tungsta-titania (VWT) catalyst and ammonia (NH3) as reductant. For application in coal- and gas-red power plants this technology is mature. However, when ring biomass the ue gas contains potassium in large amounts which deactivates....... The deNOx activity over Ag/Al2O3 used in ethanol-SCR is practically as much reduced as in the NH3-SCR case over the traditional VWT catalyst. Furthermore, poisoning with potassium leads to unselective oxidation of the hydrocarbons instead of NO reduction and SO2 concentrations as low as 20 ppm can....... At 150 C, in the presence of 10 % H2O, the catalyst under patenting matches the activity of the commercial VWT one at 220 C. However, ue gases at the tail-end position can contain up to 20 % H2O, increasing the temperature of activity parity to 180 C. Furthermore, the catalyst is also sensitive to SO2...

Nanoparticular metal oxide/anatase catalysts

DEFF Research Database (Denmark)

2010-01-01

The present invention concerns a method of preparation of nanoparticular metal oxide catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular metal oxide catalyst precursors comprising combustible crystallization seeds upon which...... the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...

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

Indian Academy of Sciences (India)

YONGZHOU YE

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

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...

Effect of Na poisoning catalyst (V2O5-WO3/TiO2) on denitration process and SO3 formation

Science.gov (United States)

Xiao, Haiping; Chen, Yu; Qi, Cong; Ru, Yu

2018-03-01

This paper aims to study the effect of alkali metal sodium (Na) poisoning on the performance of the Selective Catalytic Reduction (SCR) catalyst. The result showed that Na2SO4 poisoning leads to a reduced denitration rate of the SCR catalyst and an increase in the SO3 generation rate. Na2O poisoning leads to a significant reduction in the denitration rate of the SCR catalyst and marginally improves the formation of SO3. The maximum of the SO3 generation rate for a Na2SO4-poisoned catalyst reached 1.35%, whereas it was only 0.85% for the SCR catalyst. When the SO2 was contained in flue gas, the denitration rate for the Na2O-poisoned catalyst clearly increased by more than 28%. However, the effect of SO2 on the Na2SO4-poisoned catalyst was very slight. The denitration rate of the SCR catalyst decreased with an increase in the Na content. The BET and XRD results showed that Na poisoning of the catalyst decreased the number of acid sites, the reducibility of the catalyst, the surface area, and pore volume. The H2-TPR and NH3-TPD results show that Na decreases the number of acid sites and the reducibility of the catalyst. The FT-IR and XPS results showed that Na2O poisoning led to the decrease of V5+dbnd O bonds and the consumptions of oxygen atoms. Na2SO4 poisoning can improve surface adsorbed oxygen, which was beneficial for the SO2-SO3 conversion reaction.

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...

Optimisation of Ag loading and alumina characteristics to give sulphur-tolerant Ag/Al₂O₃ catalyst for H₂-assisted NH₃-SCR of NO_x

DEFF Research Database (Denmark)

Fogel, Sebastian; Doronkin, Dmitry E.; Gabrielsson, Pär

2012-01-01

A series of Ag/Al2O3 catalysts with different alumina precursors and different Ag loadings were tested for H2 assisted NH3-SCR of NO. The catalysts were characterised (BET, XRD, NH3-TPD, ICP-OES, TEM and UV–vis spectroscopy) and tested as fresh catalyst, during long-term cycling tests with SO2 pr....... A higher Ag loading will affect the state of Ag by increasing the ratio of Ag-clusters and particles to highly dispersed Ag ions. SO2-poisoned Ag-clusters and particles can be regenerated by the high temperature treatment in the deNOx feed, highly dispersed Ag ions cannot....

Heteropoly acid promoted V2O5/TiO2 catalysts for NO abatement with ammonia in alkali containing flue gases

DEFF Research Database (Denmark)

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

2011-01-01

V2O5/TiO2 and heteropoly acid promoted V2O5/TiO2 catalysts were prepared and characterized by N2 physisorption, XRPD and NH3-TPD. The influence of the calcination temperature from 400 to 700 1C on crystallinity and acidic properties was studied and compared with the activity for the selective...... catalytic reduction (SCR) of NO with ammonia. The SCR activity of heteropoly acid promoted catalysts was found to be much higher than for unpromoted catalysts. The stability of heteropoly acid promoted catalysts is dependent on calcination temperature and there is a gradual decrease in SCR activity...... and acidity with increase in calcination temperatures. Furthermore, the heteropoly acid promoted V2O5/TiO2 catalysts showed excellent alkali deactivation resistance and might therefore be alternative deNOx catalysts in biomass fired power plants....

Catalysts for Environmental Remediation

DEFF Research Database (Denmark)

Abrams, B. L.; Vesborg, Peter Christian Kjærgaard

2013-01-01

The properties of catalysts used in environmental remediation are described here through specific examples in heterogeneous catalysis and photocatalysis. In the area of heterogeneous catalysis, selective catalytic reduction (SCR) of NOx was used as an example reaction with vanadia and tungsta...

Congressionally Directed Project for Passive NOx Removal Catalysts Research

Energy Technology Data Exchange (ETDEWEB)

Schneider, William [Univ. of Notre Dame, IN (United States)

2014-12-29

The Recipient proposes to produce new scientific and technical knowledge and tools to enable the discovery and deployment of highly effective materials for the selective catalytic reduction (SCR) of nitrogen oxides (NOx) from lean combustion exhaust. A second goal is to demonstrate a closely coupled experimental and computational approach to heterogeneous catalysis research. These goals will be met through the completion of four primary technical objectives: First, an in-depth kinetic analysis will be performed on two prominent classes of NOx SCR catalysts, Fe- and Cu-exchanged beta and ZSM-5 zeolites, over a wide range of catalyst formulation and under identical, high conversion conditions as a function of gas phase composition. Second, the nanoscale structure and adsorption chemistry of these high temperature (HT) and low temperature (LT) catalysts will be determined using in situ and operando spectroscopy under the same reaction conditions. Third, first-principles molecular simulations will be used to model the metal-zeolite active sites, their adsorption chemistry, and key steps in catalytic function. Fourth, this information will be integrated into chemically detailed mechanistic and kinetic descriptions and models of the operation of these well- defined NOx SCR catalysts under practically relevant reaction conditions. The new knowledge and models that derive from this work will be published in the scientific literature.

SCR at bio fuel combustion

International Nuclear Information System (INIS)

Andersson, Christer; Odenbrand, I.; Andersson, L.H.

1998-10-01

by sulphatisation with sulphur dioxide. After a sulphatisation procedure with 500 ppm SO 2 (without washing) the activity was regained to at least 90 % even for heavily deactivated samples. The use of sulphatisation, periodic washing, lower flue gas temperature and use of an optimised catalyst are very promising measures to increase the catalyst lifetime and to reduce the operation costs for SCR in bio fuel fluidized bed based power plants. Therefore, a thorough investigation of these measures is warranted Figures and tables with text in English. 36 refs, 26 figs, 5 tabs

Heteropoly acid promoted Cu and Fe catalysts for the selective catalytic reduction of NO with ammonia

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Mossin, Susanne L.; Riisager, Anders

2011-01-01

Cu/TiO2, Fe/TiO2 and heteropoly acid promoted Cu/TiO2, Fe/TiO2 catalysts were prepared and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR and EPR. The catalysts exhibited only crystalline TiO2 phases with the active metals and promoters in highly dispersed state. The acidic properties...... activity and acidity was lower for promoted catalysts than for unpromoted catalysts. In the heteropoly acid promoted catalysts the SCR active Cu and Fe metals were protected from potassium poisons by bonding of the potassium to the Brønsted acid centres. Thus heteropoly acid promoted catalysts might...... be suitable for biomass fired power plant SCR applications....

Combination of Ag/Al₂O₃ and Fe-BEA for High-Activity Catalyst System for H₂-Assisted NH₃-SCR of NO x for Light-Duty Diesel Car Applications

DEFF Research Database (Denmark)

Fogel, S.; Doronkin, D. E.; Høj, J. W.

2013-01-01

Low-temperature active Ag/Al2O3 and high-temperature active Fe-BEA zeolite were combined and tested for H2-assisted NH3-selective catalytic reduction (SCR) of NO x . The catalysts were either washcoated onto separate monoliths that were placed up- or downstream of each other (dual-brick layout) o...

Study on the poisoning effect-of non-vanadium catalysts by potassium

Science.gov (United States)

Zeng, Huanmu; Liu, Ying; Yu, Xiaowei; Lin, Yasi

2018-02-01

The poisoning effect of catalyst by alkali metals is one of the problems in the selective catalytic reduction (SCR) of NO by NH3. Serious deactivation by alkali poisoning have been proved to take place in the commercial vanadium catalyst. Recently, non-vanadium catalysts such as copper oxides, manganese oxides, chromium oxides and cerium oxides have attracted special attentions in SCR application. However, their tolerance in the presence of alkali metals is still doubtful. In this paper, copper oxides, manganese oxides, chromium oxides and cerium oxides supported on TiO2 nanoparticle was prepared by impregnating method. Potassium nitrate was chosen as the precursor of poisoner. Catalytic activities of these catalysts were evaluated before and after the addition of potassium. Some characterization methods including X-ray diffraction and temperature programmed desorption was utilized to reveal the main reason of alkali deactivation.

Hydrothermally Stable Fe–W–Ti SCR Catalysts Prepared by Deposition–Precipitation

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Schill, Leonhard; Mossin, Susanne

2014-01-01

Fe/TiO2 based catalysts were prepared by incipient wetness impregnation and deposition–precipitation (DP). The catalysts were characterized by activity measurements, N2 physisorption, X-ray powder diffraction, electron paramagnetic resonance spectroscopy, energy dispersive X-ray spectroscopy, H2......-temperature programmed reduction and NH3-temperature programmed desorption. The 3 wt% Fe–10 wt% WO3/TiO2 (3Fe–10WTi-DP) catalyst prepared by DP using ammonium carbamate as a precipitating agent was found to be the most active and hydrothermally stable with 11 vol% H2O in air at 650 °C for 3 h....... The hydrothermal stability of the catalyst can be attributed to the retained crystal structure, and mild change in acidic and redox properties of the catalyst. Furthermore, hydrothermal stability of the 3Fe–10WTi-DP catalyst is competitive with that of 3Fe–ZSM-5 and much better than 3V2O5–10WO3–TiO2 catalysts...

Evaluation of Mercury Emissions from Coal-Fired Facilities with SCR and FGD Systems

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; S. C. Tseng; J. E. Locke

2006-01-31

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) and the Electric Power Research Institute (EPRI), is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP)--wet flue gas desulfurization (FGD) combination or a spray dyer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The principal purpose of this work is to develop a better understanding of the potential mercury removal ''co-benefits'' achieved by NO{sub x}, and SO{sub 2} control technologies. It is expected that these data will provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. Ultimately, this insight could help to design and operate SCR and FGD systems to maximize mercury removal. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of SCR catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. This document, the ninth in a series of topical reports, describes the results and analysis of mercury sampling performed on Unit 1 at Plant 7, a 566 MW unit burning a bituminous coal containing 3.6% sulfur. The unit is equipped with a SCR, ESP, and wet FGD to control NO{sub x}, particulate, and SO

Evaluation of Mercury Emissions from Coal-Fired Facilities with SCR and FGD Systems

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; J. E. Locke

2006-02-01

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) and the Electric Power Research Institute (EPRI), is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP)--wet flue gas desulfurization (FGD) combination or a spray dyer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The principal purpose of this work is to develop a better understanding of the potential mercury removal ''co-benefits'' achieved by NO{sub x}, and SO{sub 2} control technologies. It is expected that this data will provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. Ultimately, this insight could help to design and operate SCR and FGD systems to maximize mercury removal. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of SCR catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. This document, the tenth in a series of topical reports, describes the results and analysis of mercury sampling performed on two 468 MW units burning bituminous coal containing 1.3-1.7% sulfur. Unit 2 is equipped with an SCR, ESP, and wet FGD to control NO{sub x}, particulate, and SO{sub 2} emissions

Alternative deNO{sub x} catalysts and technologies

Energy Technology Data Exchange (ETDEWEB)

Due-Hansen, J.

2010-06-15

Two approaches are undertaken in the present work to reduce the emission of NO{sub x}: by means of catalytic removal, and by NO absorption in ionic liquids. The commercial catalyst used for the selective catalytic reduction (SCR) of nitrogen oxides exhibits high activity and selectivity towards N{sub 2}. However, the vanadia-titania-based catalyst used is very sensitive to deactivation by alkali-species (primarily potassium), which are typically present in high amounts in the flue gas when biomass is combusted. By co-firing with large amounts of CO{sub 2}-neutral straw or wood (to meet stringent CO{sub 2} emission legislation), the lifetime of the traditional SCR catalyst is thus significantly reduced due to the presence of deactivating species originating from the fuel. To develop a catalyst less susceptible to the poisons present in the flue gas, a number of catalysts have been synthesized and tested in the present work, all based on commercially available supports. A highly acidic support consisting of sulfated zirconia was chosen based on preliminary studies. A number of different active species distributed on the support were investigated, such as iron, copper and vanadium oxides. However, based on the catalysts performance in the SCR reaction and their resistances towards potassium, the most promising candidate of the formulations studied was the vanadia-loaded catalyst, i.e. V{sub 2}O{sub 5}-SO{sub 4}2-ZrO{sub 2}. This work, together with an introduction to the catalytic removal of NO{sub x}, are described in chapter 3. The remainder of the first part is concerned with the catalytic NO{sub x} removal (chapter 4) and it addresses the upscaling of the best catalyst candidate. The catalyst was mixed with the natural binding clay (sepiolite) to upscale the selected catalyst to the monolithic level, suitable for installation in gas stream with high flows, e.g. a flue gas duct of a power plant. A series of catalyst pellets with increasing levels of sepiolite were

Design of heterogeneous catalysts

DEFF Research Database (Denmark)

Frey, Anne Mette

was inspired by a computational screening, suggesting that alloys such as Ni-Fe, Co-Ni, and Co-Fe should show superior activity to the industrially used nickel catalyst. Especially the Ni-Fe system was considered to be interesting, since such alloy catalysts should be both more active and cheaper than the Ni...... catalyst. The results from the screening were experimentally verified for CO hydrogenation, CO2 hydrogenation, and simultaneous CO and CO2 hydrogenation by bimetallic Ni-Fe catalysts. These catalysts were found to be highly active and selective. The Co-Ni and Co-Fe systems were investigated for CO...... well, and the best catalyst prepared had a C5+ yield almost a factor of two higher than a standard air calcined Co catalyst. In the NH3-SCR reaction it is desirable to develop an active and stable catalyst for NOx removal in automotive applications, since the traditionally used vanadium-based catalyst...

Low-Temperature NH3–SCR of NO on Mesoporous Mn0.6Fe0.4/TiO2 Prepared by a Hydrothermal Method

DEFF Research Database (Denmark)

Schill, Leonhard; Putluru, Siva Sankar Reddy; Fehrmann, Rasmus

2014-01-01

higher (NH4)2SO4 tolerance at 150 °C compared to the impregnation preparation method. Regeneration of the (NH4)2SO4 loaded samples by heating to 400 °C was not possible whereas water washing yielded better regeneration. The catalysts are significantly more active than a commercial VWT SCR catalyst...

Technical presentation of SCR

CERN Multimedia

FI Department

2008-01-01

SCR Société des Composants Record, Montierchaume, France Monday 20 October 2008 from 9:45 to 12:00 – Room A Main Building (Bldg. 61/1-017) http://www.scr.fr SCR develops, manufactures and markets plastic dielectric capacitors (polypropylene, polyester, Teflon) for use in various applications: audio amplifiers, high-end loudspeakers, fans and extractors (multi-capacitance capacitors), pulsed lasers, flash lamps, defibrillators, beacons, power supplies, converters for rail traction drives, railway signalling devices, voltage dividers and multipliers, high voltage laboratories, etc. The company is renowned for its precision wire-wound resistors for use in power electronics and consumer electronics marketed under the SETA brand name. SCR is also experienced in the design and production of electronic circuits for various applications, such as speed variators for mono and three-phase motors, dimmers, passive filters for audio speakers, etc. Contact : M. Urs V. Rölli, e-mail: mailto:info@technictrade.ch.

Design of a periodically operated SCR reactor

International Nuclear Information System (INIS)

Kotter, M.; Lintz, H.G.; Turek, T.

1993-01-01

A new NO x abatement process uses the rotating Ljungstroem air heater of the power plant for the selective catalytic reduction (SCR) of nitrogen monoxide with ammonia. For this purpose the air heater elements are covered by a catalytically active layer. The transformation can be carried out by simple replacement of the original air heater elements. Thus nitrogen monoxide control is possible without requiring major modifications of existing power plant equipment. Two oxidic catalysts have been developed to be employed in the different temperature sections of the air heater. The activity of the catalysts has been quantified with the aid of laboratory scale experiments. The results can be described using a simple expression for the rate of the chemical reaction. NO conversion and NH 3 slip to be expected in a catalytically active Ljungstroem heat exchanger are calculated with a reactor model taking into account the gas phase mass transfer resistances. The calculations show that the proposed device can be used if the NO concentration in the flue gas does not exceed 300 ppm. Recently Kraftanlagen AG, Heidelberg, installed a catalyst air heater system at Mandalay Generating Station in Oxnard, California. The comparison of the predicted results with preliminary experimental data proves the validity of the chosen reactor model. Under the given conditions NO conversions of more than 60% can be achieved maintaining the NH 3 slip below the specified value of 10 ppm. (orig.). 19 figs., 35 refs [de

Ammonia and water sorption properties of the mineral-layered nanomaterials used as the catalysts for NOx removal from exhaust gases

International Nuclear Information System (INIS)

Olszewska, D.

2006-01-01

The object of the study is the influence of acidity and hydrophilic properties of the surface of catalyst of the selective catalytic reduction (SCR) of nitrogen oxides by NH 3 . A series of catalysts prepared with the ZrO 2 -pillared montmorillonite from Jelsovy Potok have been promoted with manganese oxides. A part of the Na + -montmorillonite form has provisionally been treated with the 20% HCl. The acidity of materials was studied by the ammonia adsorption method at the temperature of 273 and 373K. Acidic properties of catalysts depend on the step of the support preparation-the acidic activation. The activity of the SCR reaction of acid untreated support and the catalyst with MnO x which had few stronger acid centres was lower than the activity of the acid pre-treated catalyst. In this case the support had more strong acid centres. The active material of MnO x increased the NO conversion but not the influence on the amount of ammonia sorption. These centres are probably not acidic centers. The hydrophilic properties were studied by water vapour sorption at the temperature of 298K. All the samples adsorbed the same amount of water, which suggests that the NO conversion does not influence hydrophilic properties. Water molecules were physically sorbed on the surface of materials and they were replaced with NH 3 in the presence of ammonia. (author)

In-line localized monitoring of catalyst activity in selective catalytic NO.sub.x reduction systems

Science.gov (United States)

Muzio, Lawrence J [Laguna Niguel, CA; Smith, Randall A [Huntington Beach, CA

2009-12-22

Localized catalyst activity in an SCR unit for controlling emissions from a boiler, power plant, or any facility that generates NO.sub.x-containing flue gases is monitored by one or more modules that operate on-line without disrupting the normal operation of the facility. Each module is positioned over a designated lateral area of one of the catalyst beds in the SCR unit, and supplies ammonia, urea, or other suitable reductant to the catalyst in the designated area at a rate that produces an excess of the reductant over NO.sub.x on a molar basis through the designated area. Sampling probes upstream and downstream of the designated area draw samples of the gas stream for NO.sub.x analysis, and the catalyst activity is determined from the difference in NO.sub.x levels between the two probes.

Reversible and irreversible deactivation of Cu-CHA NH₃-SCR catalysts by SO₂ and SO₃

DEFF Research Database (Denmark)

Hammershøi, Peter S.; Jangjou, Yasser; Epling, William S.

2018-01-01

be divided into two parts: a reversible deactivation that is restored by the regeneration treatment, and an irreversible part. The irreversible deactivation does not affect the activation energy for NH3-SCR and display a 1:1 correlation with the S-content, consistent with deactivation by Cu-sulfate formation...... is always higher when exposed at 200 °C than at 550 °C, and in wet conditions, compared to a dry feed. The deactivation is predominantly reversible, making regeneration at 550 °C a realistic approach to handle S-poisoning in exhaust systems....

Zeolite-based SCR catalysts and their use in diesel engine emission treatment

Science.gov (United States)

Narula, Chaitanya K; Yang, Xiaofan

2015-03-24

A catalyst comprising a zeolite loaded with copper ions and at least one trivalent metal ion other than Al.sup.+3, wherein the catalyst decreases NO.sub.x emissions in diesel exhaust. The trivalent metal ions are selected from, for example, trivalent transition metal ions, trivalent main group metal ions, and/or trivalent lanthanide metal ions. In particular embodiments, the catalysts are selected from Cu--Fe-ZSM5, Cu--La-ZSM-5, Fe--Cu--La-ZSM5, Cu--Sc-ZSM-5, and Cu--In-ZSM5. The catalysts are placed on refractory support materials and incorporated into catalytic converters.

STUDY OF MERCURY OXIDATION BY SCR CATALYST IN AN ENTRAINED-FLOW REACTOR UNDER SIMULATED PRB CONDITIONS

Science.gov (United States)

A bench-scale entrained-flow reactor system was constructed for studying elemental mercury oxidation under selective catalytic reduction (SCR) reaction conditions. Simulated flue gas was doped with fly ash collected from a subbituminous Powder River Basin (PRB) coal-fired boiler ...

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....

The SS-SCR Scheme for Dynamic Spectrum Access

Directory of Open Access Journals (Sweden)

Vinay Thumar

2012-01-01

Full Text Available We integrate the two models of Cognitive Radio (CR, namely, the conventional Sense-and-Scavenge (SS Model and Symbiotic Cooperative Relaying (SCR. The resultant scheme, called SS-SCR, improves the efficiency of spectrum usage and reliability of the transmission links. SS-SCR is enabled by a suitable cross-layer optimization problem in a multihop multichannel CR network. Its performance is compared for different PU activity patterns with those schemes which consider SS and SCR separately and perform disjoint resource allocation. Simulation results depict the effectiveness of the proposed SS-SCR scheme. We also indicate the usefulness of cloud computing for a practical deployment of the scheme.

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...

Study on Optimization Experiment of SCR Denitrification Technologies in a Coal-fired Power Plant

Science.gov (United States)

Zhang, Limeng; Dong, Xinguang; Hou, Fanjun; Liu, Ke; Che, Gang

2018-01-01

Optimization experiment of SCR denitrification technologies on a 300MW unit was conducted. Adjustment of ammonia injection quantity of corresponding AIG was conducted after measuring the SCR export NOx concentration field in 250MW load, the distribution uniformity of NOx volume fraction at the outlet of both reactor A and B was improved significantly, where the relative standard deviation of NOx reduced respectively from 29.83% to 13.01% and 24.54% to 9.26%, simultaneously, the amount of ammonia escape of A, B reactor decrease respectively by 24.76%, 19.45%. The results of optimization experiment show that, optimal adjustment can improve the NOx concentration distribution, reduce the amount of ammonia escape in a certain extent, and judge whether the catalytic activity of the regional catalyzer is in good condition. As to the area where catalyst is ineffective, the effect of optimization experiment is limited, the catalyzer should be the timely replacement, so as to better protect downstream equipment.

FTIR in situ mechanistic study of the NH3-NO/NO2 "Fast SCR" reaction over a commercial Fe-ZSM-5 catalyst

Czech Academy of Sciences Publication Activity Database

Ruggeri, M. P.; Grossale, A.; Nova, I.; Tronconi, E.; Jirglová, Hana; Sobalík, Zdeněk

2012-01-01

Roč. 184, č. 1 (2012), s. 107-114 ISSN 0920-5861 R&D Projects: GA AV ČR KAN100400702; GA ČR GA203/09/1627 Institutional research plan: CEZ:AV0Z40400503 Keywords : urea /NH3 SCR * fast SCR * NO2 adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

Modeling the selective catalytic reduction of NOx by ammonia over a Vanadia-based catalyst from heavy duty diesel exhaust gases

International Nuclear Information System (INIS)

Yun, Byoung Kyu; Kim, Man Young

2013-01-01

A numerical simulation for prediction of NO X conversion over a commercial V 2 O 5 catalyst with NH 3 as a reductant was performed for a heavy duty diesel engine applications. The chemical behaviors of the SCR reactor are described by using the global NO X kinetics including standard, fast, and NH 3 oxidation reactions with the Langmuir–Hinshelwood (LH) mechanism incorporated into the commercial Boost code. After introducing mathematical models for the SCR reaction with specific reaction parameters, the effects of various parameters such as space velocities, the O 2 , H 2 O, NO 2 , and NH 3 concentrations on the NOx conversion are thoroughly studied and validated by comparing with the experimental data available in the literature. It is found that NO X conversion increases with decreasing space velocity, H 2 O concentration, and NH 3 /NO X ratio, and increasing O 2 concentration and NO 2 /NO X ratio. The study shows that not only is the present approach adopted is flexible in treating performance of the commercial V 2 O 5 based SCR catalyst, it is also accurate and efficient for the prediction of NO X conversion in diesel exhaust environments. - Highlights: ► To find the reaction parameters for LH mechanism over a commercial V2O5 catalyst. ► To investigate the effects of various parameters on the SCR NO X conversion. ► To present benchmark solutions on SCR behavior with diesel exhaust environments.

Automotive Catalyst State Diagnosis Using Microwaves

Directory of Open Access Journals (Sweden)

Moos Ralf

2015-01-01

Full Text Available The state of catalysts plays a key role in automotive exhaust gas aftertreatment. The soot or ash loading of Diesel particulate filters, the oxygen loading degree in three-way catalysts, the amount of stored ammonia in SCR catalysts, or the NOx loading degree in NOx storage catalysts are important parameters that are today determined indirectly and in a model-based manner with gas sensors installed upstream and/or downstream of the catalysts. This contribution gives an overview on a novel approach to determine the catalyst state directly by a microwave-based technique. The method exploits the fact that the catalyst housing acts as a microwave cavity resonator. As “sensing” elements, one or two simple antennas are mounted inside the catalyst canning. The electrical properties of the catalyst device (ceramic honeycomb plus coating and storage material can be measured. Preferably, the resonance characteristics, e.g., the resonance frequencies, of selected cavity modes are observed. The information on the catalyst interior obtained in such a contactless manner is very well correlated with the catalyst state as will be demonstrated for different exhaust gas aftertreatment systems.

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide.

Science.gov (United States)

Anthonysamy, Shahreen Binti Izwan; Afandi, Syahidah Binti; Khavarian, Mehrnoush; Mohamed, Abdul Rahman Bin

2018-01-01

Various types of carbon-based and non-carbon-based catalyst supports for nitric oxide (NO) removal through selective catalytic reduction (SCR) with ammonia are examined in this review. A number of carbon-based materials, such as carbon nanotubes (CNTs), activated carbon (AC), and graphene (GR) and non-carbon-based materials, such as Zeolite Socony Mobil-5 (ZSM-5), TiO 2 , and Al 2 O 3 supported materials, were identified as the most up-to-date and recently used catalysts for the removal of NO gas. The main focus of this review is the study of catalyst preparation methods, as this is highly correlated to the behaviour of NO removal. The general mechanisms involved in the system, the Langmuir-Hinshelwood or Eley-Riedeal mechanism, are also discussed. Characterisation analysis affecting the surface and chemical structure of the catalyst is also detailed in this work. Finally, a few major conclusions are drawn and future directions for work on the advancement of the SCR-NH 3 catalyst are suggested.

Understanding NOx SCR Mechanism and Activity on Cu/Chabazite Structures throughout the Catalyst Life Cycle

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Fabio; Delgass, Nick; Gounder, Rajmani; Schneider, William F.; Miller, Jeff; Yezerets, Aleksey; McEwen, Jean-Sabin; Peden, Charles HF; Howden, Ken

2014-12-09

Oxides of nitrogen (NOx) compounds contribute to acid rain and photochemical smog and have been linked to respiratory ailments. NOx emissions regulations continue to tighten, driving the need for high performance, robust control strategies. The goal of this project is to develop a deep, molecular level understanding of the function of Cu-SSZ-13 and Cu-SAPO-34 materials that catalyze the SCR of NOx with NH3.

Catalysts, systems and methods to reduce NOX in an exhaust gas stream

Science.gov (United States)

Castellano, Christopher R.; Moini, Ahmad; Koermer, Gerald S.; Furbeck, Howard

2010-07-20

Catalysts, systems and methods are described to reduce NO.sub.x emissions of an internal combustion engine. In one embodiment, an emissions treatment system for an exhaust stream is provided having an SCR catalyst comprising silver tungstate on an alumina support. The emissions treatment system may be used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines. An emissions treatment system may further comprise an injection device operative to dispense a hydrocarbon reducing agent upstream of the catalyst.

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

Science.gov (United States)

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

2016-01-15

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

EVALUATION OF MERCURY EMISSIONS FROM COAL-FIRED FACILITIES WITH SCR AND FGD SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

J.A. Withum; S.C. Tseng; J.E. Locke

2005-11-01

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) and the Electric Power Research Institute (EPRI), is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP)--wet flue gas desulfurization (FGD) combination or a spray dryer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. This document, the seventh in a series of topical reports, describes the results and analysis of mercury sampling performed on a 1,300 MW unit burning a bituminous coal containing three percent sulfur. The unit was equipped with an ESP and a limestone-based wet FGD to control particulate and SO2 emissions, respectively. At the time of sampling an SCR was not installed on this unit. Four sampling tests were performed in September 2003. Flue gas mercury speciation and concentrations were determined at the ESP outlet (FGD inlet), and at the stack (FGD outlet) using the Ontario Hydro method. Process stream samples for a mercury balance were collected to coincide with the flue gas measurements. The results show that the FGD inlet flue gas oxidized:elemental mercury ratio was roughly 2:1, with 66% oxidized mercury and 34% elemental mercury. Mercury removal, on a coal

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-01-15

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

Catalytic activity of Co-Mg-Al, Cu-Mg-Al and Cu-Co-Mg-Al mixed oxides derived from hydrotalcites in SCR of NO with ammonia

Energy Technology Data Exchange (ETDEWEB)

Chmielarz, Lucjan; Kustrowski, Piotr; Rafalska-Lasocha, Alicja [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Majda, Dorota; Dziembaj, Roman [Regional Laboratory for Physicochemical Analyses and Structural Research, Ingardena 3, 30-060 Krakow (Poland)

2002-01-10

M-Mg-Al hydrotalcites (where M=Cu{sup 2+}, Co{sup 2+} and Cu{sup 2+}+Co{sup 2+}) with M ranging from 5 to 20% (as atomic ratio) were prepared by co-precipitation method. Obtained samples were characterised by XRD and TGA techniques. The influence of transition metal content on thermal decomposition of hydrotalcites was observed. Calcination of the hydrotalcites at 600C resulted in the formation of mixed oxides with surface areas in the range 71-154m{sup 2}/g. Calcined hydrotalcites were tested as catalysts in the selective reduction of NO with ammonia (NO-SCR). The catalytic activity depends on the kind of transition metal, as well as its content. For the NO-SCR the following reactivity order was found: Cu-Mg-Al>Cu-Co-Mg-Al>Co-Mg-Al. Temperature-programmed methods (TPD, TPSR, stop flow-TPD), as well as FT-IR spectroscopy have been applied to determine interaction of NO and NH{sub 3} molecules with the catalyst surface.

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

Science.gov (United States)

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

2014-10-07

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

High performance vanadia-anatase nanoparticle catalysts for the selective catalytic reduction of NO by ammonia

DEFF Research Database (Denmark)

Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas; Riisager, Anders

2011-01-01

Highly active nanoparticle SCR deNO(x) catalysts composed of amorphous vanadia on crystalline anatase have been prepared by a sol-gel, co-precipitation method using decomposable crystallization seeds. The catalysts were characterized by means of XRPD, TEM/SEM, FT-IR, nitrogen physisorption and NH(3......) catalysts reported in the literature in the examined temperature range of 200-400 degrees C. The catalysts showed very high resistivity towards potassium poisoning maintaining a 15-30 times higher activity than the equally poisoned industrial reference catalyst, upon impregnation by 280 mu mole potassium....../g of catalyst. (C) 2011 Elsevier Inc. All rights reserved....

Ammonia sensor for closed-loop SCR control

NARCIS (Netherlands)

Wang, D.Y.; Yao, S.; Shost, M.; Yoo, J.H.; Cabush, D.; Racine, D.; Cloudt, R.P.M.; Willems, F.P.T.

2009-01-01

Selective Catalytic Reduction (SCR) is the dominant solution for meeting future NOx reduction regulations for heavy-duty diesel powertrains. SCR systems benefit from closed-loop control if an appropriate exhaust gas sensor were available. An ammonia sensor has recently been developed for use as a

Ammonia sensor for closed-loop SCR control

NARCIS (Netherlands)

Wang, D.Y.; Yao, S.; Shost, M.; Yoo, J.H.; Cabush, D.; Racine, D.; Cloudt, R.P.M.; Willems, F.P.T.

2008-01-01

Selective Catalytic Reduction (SCR) is the dominant solution for meeting future NOx reduction regulations for heavy-duty diesel powertrains. SCR systems benefit from closed-loop control if an appropriate exhaust gas sensor were available. An ammonia sensor has recently been developed for use as a

HiSCR (Hidradenitis Suppurativa Clinical Response)

DEFF Research Database (Denmark)

Kimball, B. A.; Sobell, J. M.; Zouboulis, C C

2016-01-01

Background: Determining treatment response for patients with hidradenitis suppurativa (HS) can be challenging due to limitations of current disease activity evaluations. Objective: Evaluate the novel, validated endpoint, Hidradenitis Suppurativa Clinical Response (HiSCR) and its utility as an out......Background: Determining treatment response for patients with hidradenitis suppurativa (HS) can be challenging due to limitations of current disease activity evaluations. Objective: Evaluate the novel, validated endpoint, Hidradenitis Suppurativa Clinical Response (HiSCR) and its utility...... as an outcome measure. Methods: Patients with baseline total abscess and inflammatory nodule count (AN count) of at least three and draining fistula count of 20 or fewer comprised the post hoc subpopulation analysed. HiSCR (at least a 50% reduction in total AN count, with no increase in abscess count...... week, or placebo (1 : 1 : 1). Results: The subpopulation included 132 (85.7%) patients; 70.5% women and 73.5% white. At week 16, HiSCR was achieved by 54.5% receiving weekly adalimumab, 33.3% every other week, and 25.6% placebo and HS-PGA Response was achieved by 20.5% receiving weekly adalimumab, 6...

Spent catalyst waste management. A review. Part 1. Developments in hydroprocessing catalyst waste reduction and use

Energy Technology Data Exchange (ETDEWEB)

Marafi, M.; Stanislaus, A. [Petroleum Refining Department, Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, 13109-Safat (Kuwait)

2008-04-15

Solid catalysts containing metals, metal oxides or sulfides, which play a key role in the refining of petroleum to clean fuels and many other valuable products, become solid wastes after use. In many refineries, the spent catalysts discarded from hydroprocessing units form a major part of these solid wastes. Disposal of spent hydroprocessing catalysts requires compliance with stringent environmental regulations because of their hazardous nature and toxic chemicals content. Various options such as minimizing spent catalyst waste generation by regeneration and reuse, metals recovery, utilization to produce useful materials and treatment for safe disposal, could be considered to deal with the spent catalyst environmental problem. In this paper, information available in the literature on spent hydroprocessing catalyst waste reduction at source by using improved more active and more stable catalysts, regeneration, rejuvenation and reuse of deactivated catalysts in many cycles, and reusing in other processes are reviewed in detail with focus on recent developments. Available methods for recycling of spent hydroprocessing catalysts by using them as raw materials for the preparation of active new catalysts and many other valuable products are also reviewed. (author)

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...

H{sub 2} assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} for automotive applications

Energy Technology Data Exchange (ETDEWEB)

Fogel, S.

2013-05-15

The up-coming strict emission legislation demands new and improved catalysts for diesel vehicle deNO{sub x}. The demand for low-temperature activity is especially challenging. H{sub 2}-assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} has shown a very promising low-temperature activity and a combination of Ag/Al{sub 2}O{sub 3} and Fe-BEA can give a high NO{sub x} conversion in a broad temperature window without the need to dose H{sub 2} at higher temperatures. The aim of this study has been to investigate the combined Ag/Al{sub 2}O{sub 3} and Fe-BEA catalyst system both at laboratory-scale and in full-scale engine bench testing. The catalysts were combined both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al{sub 2}O{sub 3} catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study has been the preparation of monolithic catalyst bricks for the catalyst testing. A high SBET and higher Ag loading gave a high sulphur tolerance and activity. It was believed that the high S{sub BET} is needed to give a higher NH{sub 3} adsorption capacity, necessary for the SCR reaction. A higher Ag loading gives more Ag sites and probably a favourable Ag dispersion. Testing with sulphur gave an increased activity of the catalysts. Testing of monolithic catalysts showed a similar activity enhancement after a few standard test cycles. A change in the dispersion or state of Ag can be possible reasons for the activation seen and the activation was believed to be related to Ag and not the alumina. Small-scale laboratory testing showed that it was preferred to have Ag/Al{sub 2}O{sub 3} either upstream or as the outer layer of Fe-BEA. This was attributed to complete NH{sub 3} oxidation over Fe-BEA giving a deficit of NH{sub 3} over the Ag/Al{sub 2}O{sub 3} if it was placed downstream or as the inner layer

Vanadia on sulphated-ZrO2, a promising catalyst for NO abatement with ammonia in alkali containing flue gases

DEFF Research Database (Denmark)

Kustov, Arkadii; Kustova, Marina; Fehrmann, Rasmus

2005-01-01

in the total acidity is less pronounced in this case. The results of NO SCR with ammonia reveal a noticeable shift of the maximum catalytic activity towards higher temperatures in going from the conventional catalyst to vanadia supported on sulphated zirconia. The loading of the catalysts with potassium leads...

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....

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...

Spectroscopic Insights into Copper-Based Microporous Zeolites for NH3-SCR of NOx and Methane-to-Methanol Activation

OpenAIRE

Oord, R.

2017-01-01

Smog has received a lot of attention and is still a major problem in big cities all over the world. A major contribution to smog are nitrogen oxides (NOx), which are mainly produced by road transport, industrial processes and power plants. A lot of research has been put into the reduction of these pollutants, and heterogeneous catalysts have made a major contribution to this field. Selective catalytic reduction (SCR) is an efficient technology to reduce these NOx, and is already used in diese...

Alternative deNOx catalysts and technologies

DEFF Research Database (Denmark)

Due-Hansen, Johannes

The present thesis entitled Alternative deNOx Catalysts and technologies revolves around the topic of removal of nitrogen oxides. Nitrogen oxides, NOx, are unwanted byproducts formed during combustion (e.g. in engines or power plants). If emitted to the atmosphere, they are involved...... in the formation of acid rain and photochemical smog. Some basic concepts and reactions regarding the formation and removal of NOx are presented in chapter 1 and 2. Two approaches are undertaken in the present work to reduce the emission of NOx: by means of catalytic removal, and by NO absorption in ionic liquids....... The commercial catalyst used for the selective catalytic reduction (SCR) of nitrogen oxides exhibits high activity and selectivity towards N2. However, the vanadia-titania-based catalyst used is very sensitive to deactivation by alkali-species (primarily potassium), which are typically present in high amounts...

New developments of high dust-SCR technology in the cement industry results of pilot tests in Solnhofen and development state of a full scale SCR unit; Nouveaux developpements de la technologie SCR ''High Dust'' dans l'industrie du ciment - resultats de tests pilotes a Solnhoffen et etat de developpement d'une unite pilote a l'echelle

Energy Technology Data Exchange (ETDEWEB)

Samant, G. [Lurgi Energie und Entsorgung GmbH, Frankfurt (Germany); Sauter, G. [Soinhofer Portland Zementwerke AG, Solnhofen (Germany); Haug, N. [Agence Federale de l' Environnement, Berlin (Germany)

2001-07-01

The production of clinker in the cement industry involve the formation of nitrous oxides, and the emission limits are becoming more stringent from year to year. The added up total NOx emissions from the European cement industry amounts at present approx. 450.000 Mg/year. As such it is high time for the decision to develop and implement a technology to reduce NOx-emissions. At present SCR technology which is implemented in the glass industry, waste incineration and power plants seems to be the best economical and ecological solution for cement industry. In the period time from 1997 to the end of 1999 pilot plant test work was carried out by the companies 'Solnhofer Portland Zementwerke AG' and 'mg Engineering Lurgi' in the cement plant in Solnhofen. The results of pilot plan test work show that NOx reduction rates above 90% with NH{sub 3} slip less then 5 vppm can be achieved. The results of the test work with different type of catalysts are discussed. Based on the results of the test work a suitable SCR-process for cement industry is developed. At present a High-Dust-SCR demonstration plant at 'Solnhofer Portland Zementwerke AG' with the help of German Federal Environmental Agency, UBA-Berlin, is under commissioning and going on stream. (authors)

NO oxidation on Zeolite Supported Cu Catalysts: Formation and Reactivity of Surface Nitrates

Energy Technology Data Exchange (ETDEWEB)

Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton; Gao, Feng; Wang, Yilin; Szanyi, Janos; Peden, Charles HF

2016-04-18

The comparative activities of a small-pore Cu-CHA and a large-pore Cu-BEA catalyst for the selective catalytic reduction (SCR) of NOx with NH3, and for the oxidation of NO to NO2 and the subsequent formation of surface nitrates were investigated. Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity. Furthermore, Cu-CHA is even less active than Cu-BEA in catalyzing NO oxidation but is clearly more active for SCR reactions. Temperature-programed desorption (TPD) experiments following the adsorption of (NO2 + NO + O2) with different NO2:NO ratios reveal that the poor NO oxidation activity of the two catalysts is not due to the formation of stable surface nitrates. On the contrary, NO is found to reduce and decompose the surface nitrates on both catalysts. To monitor the reaction pathways, isotope exchange experiments were conducted by using 15NO to react with 14N-nitrate covered catalyst surfaces. The evolution of FTIR spectra during the isotope exchange process demonstrates that 14N-nitrates are simply displaced with no formation of 15N-nitrates on the Cu-CHA sample, which is clearly different from that observed on the Cu-BEA sample where formation of 15N-nitrates is apparent. The results suggest that the formal oxidation state of N during the NO oxidation on Cu-CHA mainly proceeds from its original +2 to a +3 oxidation state, whereas reaching a higher oxidation state for N, such as +4 or +5, is possible on Cu-BEA. The authors at PNNL gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

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

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

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

Science.gov (United States)

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

2017-07-12

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

DeNOx Abatement over Sonically Prepared Iron-Substituted Y, USY and MFI Zeolite Catalysts in Lean Exhaust Gas Conditions

Science.gov (United States)

Stachurska, Patrycja; Kuterasiński, Łukasz; Dziedzicka, Anna; Górecka, Sylwia; Chmielarz, Lucjan; Łojewska, Joanna; Sitarz, Maciej

2018-01-01

Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C. PMID:29301370

Poisoning of vanadia based SCR catalysts by potassium:influence of catalyst composition and potassium mobility

DEFF Research Database (Denmark)

Olsen, Brian Kjærgaard; Kügler, Frauke; Jensen, Anker Degn

2016-01-01

exposure temperatures slowdown the deactivation. K2SO4 causes a lower rate of deactivation compared to KCl. This may be related to a faster transfer of potassium from the solid KCl matrix to the catalyst, however, it cannot be ruled out toalso be caused by a significantly larger particle size of the K2SO4...

The J3 SCR model applied to resonant converter simulation

Science.gov (United States)

Avant, R. L.; Lee, F. C. Y.

1985-01-01

The J3 SCR model is a continuous topology computer model for the SCR. Its circuit analog and parameter estimation procedure are uniformly applicable to popular computer-aided design and analysis programs such as SPICE2 and SCEPTRE. The circuit analog is based on the intrinsic three pn junction structure of the SCR. The parameter estimation procedure requires only manufacturer's specification sheet quantities as a data base.

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.

The protective effect of SCR(15-18) on cerebral ischemia-reperfusion injury.

Science.gov (United States)

Li, Shu; Xian, Jinhong; He, Li; Luo, Xue; Tan, Bing; Yang, Yongtao; Liu, Gaoke; Wang, Zhengqing

2011-10-01

Soluble complement receptor type 1 (sCR1), a potent inhibitor of complement activation, has been shown to protect brain cells against cerebral ischemic/reperfusion (CI/R) injury due to its decay-accelerating activity for C3/C5 convertase and co-factor activity for C3b/C4b degradation. However, the effect of short consensus repeats (SCRs) 15-18, one of active domains of sCR1 with high C3b/C4b degradability, has not been demonstrated. Here, we investigated the protective effect of recombinant SCR(15-18) protein in middle cerebral artery occlusion (MCAO)-induced focal CI/R injury. Recombinant SCR(15-18) protein was successfully expressed in Escherichia coli and refolded to its optimal bioactivity. Seventy-five Sprague-Dawley rats were randomly assigned into three groups: sham-operated group, CI/R group, and SCR(15-18)+CI/R group pretreated with 20 mg/kg SCR(15-18) protein. After 2 hours of MCAO and subsequent 24 hours of reperfusion, rats were evaluated for neurological deficits and cerebral infarction. Polymorphonuclear leukocyte accumulation, C3b deposition, and morphological changes in cerebral tissue were also estimated. SCR(15-18) pretreatment induced a 20% reduction of infarct size and an improvement of neurological function with 22·2% decrease of neurological deficit scores. Inhibition of cerebral neutrophils infiltration by SCR(15-18) was indicated from the reduction of myeloperoxidase activity in SCR(15-18)+CI/R rats. Decreased C3b deposition and improved morphological changes were also found in cerebral tissue of SCR(15-18)-treated rats. Our studies suggest a definitive moderately protective effect of SCR(15-18) against CI/R damage and provide preclinical experimental evidence supporting the possibility of using it as a small anti-complement therapeutic agent for CI/R injury therapy.

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

Directory of Open Access Journals (Sweden)

Markus Dietrich

2017-07-01

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

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

Science.gov (United States)

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

2017-01-01

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

Modified fly ash from municipal solid waste incineration as catalyst support for Mn-Ce composite oxides

Science.gov (United States)

Chen, Xiongbo; Liu, Ying; Yang, Ying; Ren, Tingyan; Pan, Lang; Fang, Ping; Chen, Dingsheng; Cen, Chaoping

2017-08-01

Fly ash from municipal solid waste incineration was modified by hydrothermal treatment and used as catalyst support for Mn-Ce composite oxides. The prepared catalyst showed good activity for the selective catalytic reduction (SCR) of NO by NH3. A NO conversion of 93% could be achieved at 300 °C under a GHSV of 32857 h-1. With the help of characterizations including XRD, BET, SEM, TEM, XPS and TPR, it was found that hydrothermal treatment brought a large surface area and abundant mesoporous to the modified fly ash, and Mn-Ce composite oxides were highly dispersed on the surface of the support. These physical and chemical properties were the intrinsic reasons for the good SCR activity. This work transformed fly ash into high value-added products, providing a new approach to the resource utilization and pollution control of fly ash.

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

Evaluation of mechanical properties in metal wire mesh supported selective catalytic reduction (SCR) catalyst structures

Science.gov (United States)

Rajath, S.; Siddaraju, C.; Nandakishora, Y.; Roy, Sukumar

2018-04-01

The objective of this research is to evaluate certain specific mechanical properties of certain stainless steel wire mesh supported Selective catalytic reduction catalysts structures wherein the physical properties of the metal wire mesh and also its surface treatments played vital role thereby influencing the mechanical properties. As the adhesion between the stainless steel wire mesh and the catalyst material determines the bond strength and the erosion resistance of catalyst structures, surface modifications of the metal- wire mesh structure in order to facilitate the interface bonding is therefore very important to realize enhanced level of mechanical properties. One way to enhance such adhesion properties, the stainless steel wire mesh is treated with the various acids, i.e., chromic acid, phosphoric acid including certain mineral acids and combination of all those in various molar ratios that could generate surface active groups on metal surface that promotes good interface structure between the metal- wire mesh and metal oxide-based catalyst material and then the stainless steel wire mesh is dipped in the glass powder slurry containing some amount of organic binder. As a result of which the said catalyst material adheres to the metal-wire mesh surface more effectively that improves the erosion profile of supported catalysts structure including bond strength.

System and method for determining an ammonia generation rate in a three-way catalyst

Science.gov (United States)

Sun, Min; Perry, Kevin L; Kim, Chang H

2014-12-30

A system according to the principles of the present disclosure includes a rate determination module, a storage level determination module, and an air/fuel ratio control module. The rate determination module determines an ammonia generation rate in a three-way catalyst based on a reaction efficiency and a reactant level. The storage level determination module determines an ammonia storage level in a selective catalytic reduction (SCR) catalyst positioned downstream from the three-way catalyst based on the ammonia generation rate. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the ammonia storage level.

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

Directory of Open Access Journals (Sweden)

Ralf Moos

2010-07-01

Full Text Available Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

Science.gov (United States)

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters. PMID:22163575

Catalysts as sensors--a promising novel approach in automotive exhaust gas aftertreatment.

Science.gov (United States)

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NO(x) traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NO(x)-loading of lean NO(x) traps, and the soot loading of Diesel particulate filters.

Influence of reaction products of K-getter fuel additives on commercial vanadia-based SCR catalysts

DEFF Research Database (Denmark)

Castellino, Francesco; Jensen, Anker Degn; Johnsson, Jan Erik

2009-01-01

, deactivation rates up to 3%/day have been measured. The spent catalysts have been characterized by bulk chemical analysis, Hg-porosimetry and SEM-EDX. NH3-chemisorption tests on the spent elements and activity tests on catalyst powders obtained by crushing the monoliths have also been carried out. The catalyst...... characterization has shown that poisoning by K is the main deactivation mechanism. The results show that binding K in K–P salts will not reduce the rate of catalyst deactivation....... as a K-getter additive. The formed aerosols have been characterized by using both a SMPS system and a low pressure cascade impactor, showing a dual-mode volume-based size distribution with a first peak at around 30 nm and a second one at diameters >1 μm. The different peaks have been associated...

Experimental study on the particulate matter and nitrogenous compounds from diesel engine retrofitted with DOC+CDPF+SCR

Science.gov (United States)

Zhang, Yunhua; Lou, Diming; Tan, Piqiang; Hu, Zhiyuan

2018-03-01

The increasingly stringent emission regulations will mandate the retrofit of after-treatment devices for in-use diesel vehicles, in order to reduce their substantial particulate matter and nitrogen oxides (NOX) emissions. In this paper, a combination of DOC (diesel oxidation catalyst), CDPF (catalytic diesel particulate filter) and SCR (selective catalytic reduction) retrofit for a heavy-duty diesel engine was employed to perform experiment on the engine test bench to evaluate the effects on the particulate matter emissions including particle number (PN), particle mass (PM), particle size distributions and nitrogenous compounds emissions including NOX, nitrogen dioxide (NO2)/NOX, nitrous oxide (N2O) and ammonia (NH3) slip. In addition, the urea injection was also of our concern. The results showed that the DOC+CDPF+SCR retrofit almost had no adverse effect on the engine power and fuel consumption. Under the test loads, the upstream DOC and CDPF reduced the PN and PM by an average of 91.6% and 90.9%, respectively. While the downstream SCR brought about an average decrease of 85% NOX. Both PM and NOX emission factors based on this retrofit were lower than China-Ⅳ limits (ESC), and even lower than China-Ⅴ limits (ESC) at medium and high loads. The DOC and CDPF changed the particle size distributions, leading to the increase in the proportion of accumulation mode particles and the decrease in the percentage of nuclear mode particles. This indicates that the effect of DOC and CDPF on nuclear mode particles was better than that of accumulation mode ones. The upstream DOC could increase the NO2/NOX ratio to 40%, higher NO2/NOX ratio improved the efficiency of CDPF and SCR. Besides, the N2O emission increased by an average of 2.58 times after the retrofit and NH3 slip occurred with the average of 26.7 ppm. The rate of urea injection was roughly equal to 8% of the fuel consumption rate. The DOC+CDPF+SCR retrofit was proved a feasible and effective measurement in terms

Retrofit SCR system for NOx control from heavy-duty mining equipment

International Nuclear Information System (INIS)

Mannan, M.A.

2009-01-01

Diesel engines are used extensively in the mining industry and offer many advantages. However, particulate matter (PM) emissions and nitrogen oxide emissions (NOx) are among its disadvantages. A significant concern related to PM and NOx in an underground mine involves the use of diesel exhaust after treatment systems such as diesel particulate filters and selective catalytic reduction (SCR). This presentation discussed NOx and PM control and provided a description of an SCR system and examples of SCR retrofits. Options for NOx control were discussed and a case study involving the installation of an SCR retrofit system in an underground mine operated by Sifto Salt was also presented. The purpose of the case study was to identify cost effective retrofit solutions to lower nitrogen dioxide emissions from heavy-duty trucks operating in underground mines. The case study illustrated and presented the candidate vehicle, baseline emissions, a BlueMax SCR retrofit solution, and BlueMax installation. 1 tab., 6 figs.

Innovative clean coal technology (ICCT): demonstration of selective catalytic reduction (SCR) technology for the control of nitrogen oxide (NOx) emission from high-sulfur, coal-fired boilers - economic evaluation of commercial-scale SCR applications for utility boilers

International Nuclear Information System (INIS)

Healy, E.C.; Maxwell, J.D.; Hinton, W.S.

1996-09-01

This report presents the results of an economic evaluation produced as part of the Innovative Clean Coal Technology project, which demonstrated selective catalytic reduction (SCR) technology for reduction of NO x emissions from utility boilers burning U.S. high-sulfur coal. The document includes a commercial-scale capital and O ampersand M cost evaluation of SCR technology applied to a new facility, coal-fired boiler utilizing high-sulfur U.S. coal. The base case presented herein determines the total capital requirement, fixed and variable operating costs, and levelized costs for a new 250-MW pulverized coal utility boiler operating with a 60-percent NO x removal. Sensitivity evaluations are included to demonstrate the variation in cost due to changes in process variables and assumptions. This report also presents the results of a study completed by SCS to determine the cost and technical feasibility of retrofitting SCR technology to selected coal-fired generating units within the Southern electric system

Reduction of Nitrogen Oxides using zeolite catalysts exchanged with cobalt

International Nuclear Information System (INIS)

Garcia M, E.A.; Bustamante L, F.; Montes de C, C.

1999-01-01

The Selective Catalytic Reduction (SCR) of NOx by methane in excess oxygen was studied over several zeolite catalysts; namely cobalt loaded mordenite, ferrierite, SM-5 and the corresponding acid forms. When NO2 predominated n the NOx mixture the acid forms showed the highest N2 formation rates under dry conditions. Mordenite supported catalysts were the most active ones followed by ferrierite and ZSM-5. The most active Co-Mordenite catalyst was tested using a NOx mixture, containing mostly NO, under dry conditions and in the presence of water and SO2. The addition of 8 % water to the reaction mixture lead to a reversible deactivation, mainly at low temperatures. When the reaction mixture contained 60 ppm SO2, the N2 formation rate decreased about a half likely due to SO2 poisoning

Cost and Fuel Efficient SCR-only Solution for post-2010 HD Emission Standards

NARCIS (Netherlands)

Cloudt, R.P.M.; Willems, F.P.T.; Heijden, van der P.

2009-01-01

A promising SCR-only solution is presented to meetpost-2010 NOx emission targets for heavy dutyapplications. The proposed concept is based on anengine from a EURO IV SCR application, which isconsidered optimal with respect to fuel economy andcosts. The addition of advanced SCR after

Long time experience with deactivation and regeneration of DENOX catalysts and evaluation with the Internet database LEONID; Langzeiterfahrung mit der Deaktivierung und Regeneration von DENOX-Katalysatoren sowie Auswertung mit der Internet-Datenbank LEONID

Energy Technology Data Exchange (ETDEWEB)

Brandenstein, J.; Dieckmann, H.J.; Gutberlet, H. [E.ON Engineering GmbH, Gelsenkirchen (Germany)

2008-07-01

The paper gives an overview over the long-term catalyst deactivation and the main reasons for catalyst aging. The chemical composition of de-activated catalysts provides information on the optimum catalyst regeneration process. The long-term deactivation behaviour of regenerated catalysts is compared to new catalysts. All characteristic catalyst features are listed in an online 'LEONID'-database, developed by E.ON Engineering. The database provides the basis for long-term catalyst management of all connected SCR systems. (orig.)

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

DEFF Research Database (Denmark)

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

2018-01-01

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

The energy consumption and environmental impacts of SCR technology in China

Energy Technology Data Exchange (ETDEWEB)

Liang, Zengying; Ma, Xiaoqian; Lin, Hai; Tang, Yuting [School of Electric Power, Guangdong Key Laboratory of Clean Energy Technology, South China University of Technology, Guangzhou 510640 (China)

2011-04-15

Energy and environment are drawing greater attention today, particularly with the rapid development of the economy and increase consumption of energy in China. At present, coal-fired power plants are mainly responsible for atmospheric air pollution. The selective catalytic reduction (SCR) technology is a highly effective method for NO{sub X} control. The present study identified and quantified the energy consumption and the environmental impacts of SCR system throughout the whole life cycle, including production and transportation of manufacturing materials, installation and operation of SCR technology. The analysis was conducted with the utilization of life cycle assessment (LCA) methodology which provided a quantitative basis for assessing potential improvements in the environmental performance of the system. The functional unit of the study was 5454 t NO{sub X} emission from an existing Chinese pulverized coal power plant for 1 year. The current study compared life cycle emissions from two types of de-NO{sub X} technologies, namely the SCR technology and the selective non-catalytic reduction (SNCR) technology, and the case that NO{sub X} was emitted into atmosphere directly. The results showed that the environmental impact loading resulting from SCR technology (66810 PET{sub 2000}) was smaller than that of flue gas emitted into atmosphere directly (164121 PET{sub 2000}) and SNCR technology (105225 PET{sub 2000}). More importantly, the SCR technology is much more effective at the elimination of acidification and nutrient enrichment than SNCR technology and the case that NO{sub X} emitted into atmosphere directly. This SCR technology is more friendly to the environment, and can play an important role in NO{sub X} control for coal-fired power plants as well as industrial boilers. (author)

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Functional characterization of sucrose phosphorylase and scrR, a regulator of sucrose metabolism in Lactobacillus reuteri.

Science.gov (United States)

Teixeira, Januana S; Abdi, Reihaneh; Su, Marcia Shu-Wei; Schwab, Clarissa; Gänzle, Michael G

2013-12-01

Lactobacillus reuteri harbours alternative enzymes for sucrose metabolism, sucrose phosphorylase, fructansucrases, and glucansucrases. Sucrose phosphorylase and fructansucrases additionally contribute to raffinose metabolism. Glucansucrases and fructansucrases produce exopolysaccharides as alternative to sucrose hydrolysis. L. reuteri LTH5448 expresses a levansucrase (ftfA) and sucrose phosphorylase (scrP), both are inducible by sucrose. This study determined the contribution of scrP to sucrose and raffinose metabolism in L. reuteri LTH5448, and elucidated the role of scrR in regulation sucrose metabolism. Disruption of scrP and scrR was achieved by double crossover mutagenesis. L. reuteri LTH5448, LTH5448ΔscrP and LTH5448ΔscrR were characterized with respect to growth and metabolite formation with glucose, sucrose, or raffinose as sole carbon source. Inactivation of scrR led to constitutive transcription of scrP and ftfA, demonstrating that scrR is negative regulator. L. reuteri LTH5448 and the LTH5448ΔscrP or LTH5448ΔscrR mutant strains did not differ with respect to glucose, sucrose or raffinose utilization. However, L. reuteri LTH5448ΔscrP produced more levan, indicating that the lack of sucrose phosphorylase is compensated by an increased metabolic flux through levansucrase. In conclusion, the presence of alternate pathways for sucrose and raffinose metabolism and their regulation indicate that these substrates, which are abundant in plants, are preferred carbohydrate sources for L. reuteri. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cost and fuel efficient SCR-only solution for post-2010 HD emission standards

NARCIS (Netherlands)

Cloudt, R.P.M.; Willems, F.P.T.; Heijden, P.V.A.M. van der

2009-01-01

A promising SCR-only solution is presented to meet post-2010 NOx emission targets for heavy duty applications. The proposed concept is based on an engine from a EURO IV SCR application, which is considered optimal with respect to fuel economy and costs. The addition of advanced SCR after treatment

MECHANISTIC STUDIES AND DESIGN OF HIGHLY ACTIVE CUPRATE CATALYSTS FOR THE DIRECT DECOMPOSITION AND SELECTIVE REDUCTION OF NITRIC OXIDE AND HYDROCARBONS TO NITROGEN FOR ABATEMENT OF STACK EMISSIONS

Energy Technology Data Exchange (ETDEWEB)

None

1998-04-30

A flow trough type catalytic reactor system was adequately modified for NO related catalytic and adsorption measurements, including the on-line connection of a digital chemiluminescent NO-NO{sub x} analyzer to the reactor outlet system. Moreover, we have largely completed the installation of an FTIR coupled catalytic system containing a HTEC cell for high temperature DRIFT studies. Three different barium cuprate samples, Ba{sub 2}CuO{sub 3}, BaCuO{sub 2}, and Ba{sub 2}Cu{sub 3}O{sub 5} were synthesized and characterized by powder XRD for catalytic tests. Prior to catalytic studies over these cuprates, a new, liquid indium based supported molten metal catalyst (In-SMMC) was tested in the reduction of NO by various reductants. In the presence of excess O{sub 2} and H{sub 2}O, the In-SMMC proved to be more active for the selective catalytic reduction (SCR) of NO to N{sub 2} by ethanol than most other catalysts. Using C{sub 1}-C{sub 3} alcohols as reductants, self sustained periodic oscillations observed in the NO{sub x} concentrations of reactor effluents indicated the first time that radical intermediates can be involved in the SCR of NO by alcohols. Further, In-SMMC is the only effective and water tolerant SCR catalyst reported thus far which contains SiO{sub 2} support. Thus, this novel catalyst opens up a promising new alternative for developing an effective and durable catalyst for NO{sub x} abatement in stack emission.

Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

Directory of Open Access Journals (Sweden)

Liliana Lazar

2012-02-01

Full Text Available The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a great deal of interest. Selective catalytic reduction (SCR, noble metal and transition metal oxide based catalysts have been investigated at both the laboratory and plant scale with this objective. A review article published in 2006 covers the progress in the elemental mercury (Hgel catalytic oxidation area. This paper brings the review in this area up to date. To this end, 110 papers including several reports and patents are reviewed. For each type of catalyst the possible mechanisms as well as the effect of flue gas components on activity and stability are examined. Advantages and main problems are analyzed. The possible future directions of catalyst development in this environmental research area are outlined.

Simulation and Optimization of SCR System for Direct-injection Diesel Engine

Directory of Open Access Journals (Sweden)

Guanqiang Ruan

2014-11-01

Full Text Available The turbo diesel SCR system has been researched and analyzed in this paper. By using software of CATIA, three-dimensional physical model of SCR system has been established, and with software of AVL-FIRE, the boundary conditions have been set, simulated and optimized. In the process of SCR system optimizing, it mainly optimized the pray angle. Compare the effects of processing NO to obtain batter optimization results. At last the optimization results are compared by bench test, and the experimental results are quite consistent with simulation.

Influence of real-world engine load conditions on nanoparticle emissions from a DPF and SCR equipped heavy-duty diesel engine.

Science.gov (United States)

Thiruvengadam, Arvind; Besch, Marc C; Carder, Daniel K; Oshinuga, Adewale; Gautam, Mridul

2012-02-07

The experiments aimed at investigating the effect of real-world engine load conditions on nanoparticle emissions from a Diesel Particulate Filter and Selective Catalytic Reduction after-treatment system (DPF-SCR) equipped heavy-duty diesel engine. The results showed the emission of nucleation mode particles in the size range of 6-15 nm at conditions with high exhaust temperatures. A direct result of higher exhaust temperatures (over 380 °C) contributing to higher concentration of nucleation mode nanoparticles is presented in this study. The action of an SCR catalyst with urea injection was found to increase the particle number count by over an order of magnitude in comparison to DPF out particle concentrations. Engine operations resulting in exhaust temperatures below 380 °C did not contribute to significant nucleation mode nanoparticle concentrations. The study further suggests the fact that SCR-equipped engines operating within the Not-To-Exceed (NTE) zone over a critical exhaust temperature and under favorable ambient dilution conditions could contribute to high nanoparticle concentrations to the environment. Also, some of the high temperature modes resulted in DPF out accumulation mode (between 50 and 200 nm) particle concentrations an order of magnitude greater than typical background PM concentrations. This leads to the conclusion that sustained NTE operation could trigger high temperature passive regeneration which in turn would result in lower filtration efficiencies of the DPF that further contributes to the increased solid fraction of the PM number count.

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...

Cloning and Characterization of ThSHRs and ThSCR Transcription Factors in Taxodium Hybrid 'Zhongshanshan 406'.

Science.gov (United States)

Wang, Zhiquan; Yin, Yunlong; Hua, Jianfeng; Fan, Wencai; Yu, Chaoguang; Xuan, Lei; Yu, Fangyuan

2017-07-20

Among the GRAS family of transcription factors, SHORT ROOT (SHR) and SCARECROW (SCR) are key regulators of the formation of root tissues. In this study, we isolated and characterized two genes encoding SHR proteins and one gene encoding an SCR protein: ThSHR1 (Accession Number MF045148), ThSHR2 (Accession Number MF045149) and ThSCR (Accession Number MF045152) in the adventitious roots of Taxodium hybrid 'Zhongshanshan'. Gene structure analysis indicated that ThSHR1 , ThSHR2 and ThSCR are all intron free. Multiple protein sequence alignments showed that each of the corresponding proteins, ThSHR1, ThSHR2 and ThSCR, contained five well-conserved domains: leucine heptad repeat I (LHRI), the VHIID motif, leucine heptad repeat II (LHR II), the PFYRE motif, and the SAW motif. The phylogenetic analysis indicated that ThSCR was positioned in the SCR clade with the SCR proteins from eight other species, while ThSHR1 and ThSHR2 were positioned in the SHR clade with the SHR proteins from six other species. Temporal expression patterns of these genes were profiled during the process of adventitious root development on stem cuttings. Whereas expression of both ThSHR2 and ThSCR increased up to primary root formation before declining, that of ThSHR1 increased steadily throughout adventitious root formation. Subcellular localization studies in transgenic poplar protoplasts revealed that ThSHR1, ThSHR2 and ThSCR were localized in the nucleus. Collectively, these results suggest that the three genes encode Taxodium GRAS family transcription factors, and the findings contribute to improving our understanding of the expression and function of SHR and SCR during adventitious root production, which may then be manipulated to achieve high rates of asexual propagation of valuable tree species.

Alternative alkali resistant deNO{sub x} technologies. Appendix 1

Energy Technology Data Exchange (ETDEWEB)

Putluru, S.S.R.; Degn Jensen, A.

2011-07-01

The increased use of biomass as fuel has created some new challenges to establish SCR flue gas treatment technology. One of these challenges comes from biomass complex chemical composition, which includes potassium shown to have a negative impact on the SCR catalyst. Studies have shown that potassium deactivates SCR catalyst and reduces its ability to reduce NO to N{sub 2}. An attempt was made to protect the SCR catalyst from alkali poisoning by the imposition of a coating on the catalyst surface. Various compounds were coated on a commercial catalyst supplied by Haldor Topsoee A/S and tested for alkali poisoning resistance. These materials were broadly divided as metal oxides, zeolites and other materials. The coated catalysts were exposed to potassium chloride aerosols at 350 deg. C for 650-1200 h. SCR activity, SEM and EDX measurements were performed to analyze the coated catalysts resistance to potassium poisoning. Coated catalysts (Mg, Mg containing compounds and Zeolites) showed appreciable alkali resistivity compared to the uncoated reference catalyst. Coated catalysts showed high potassium concentration at the surface of the coating and low potassium concentration across the cross section when compared to the uncoated reference catalyst. Thus, it is assumed that the coating layer accumulates the potassium at the surface and prevents to penetrate through the catalyst. The overall assessment is that it is possible to protect an SCR catalyst from potassium poisoning by the imposition of coating layer. (Author)

Alloy SCR-3 resistant to stress corrosion cracking

International Nuclear Information System (INIS)

Kowaka, Masamichi; Fujikawa, Hisao; Kobayashi, Taiki

1977-01-01

Austenitic stainless steel is used widely because the corrosion resistance, workability and weldability are excellent, but the main fault is the occurrence of stress corrosion cracking in the environment containing chlorides. Inconel 600, most resistant to stress corrosion cracking, is not necessarily safe under some severe condition. In the heat-affected zone of SUS 304 tubes for BWRs, the cases of stress corrosion cracking have occurred. The conventional testing method of stress corrosion cracking using boiling magnesium chloride solution has been problematical because it is widely different from actual environment. The effects of alloying elements on stress corrosion cracking are remarkably different according to the environment. These effects were investigated systematically in high temperature, high pressure water, and as the result, Alloy SCR-3 with excellent stress corrosion cracking resistance was found. The physical constants and the mechanical properties of the SCR-3 are shown. The states of stress corrosion cracking in high temperature, high pressure water containing chlorides and pure water, polythionic acid, sodium phosphate solution and caustic soda of the SCR-3, SUS 304, Inconel 600 and Incoloy 800 are compared and reported. (Kako, I.)

State Estimation in the Automotive SCR DeNOx Process

DEFF Research Database (Denmark)

Zhou, Guofeng; Jørgensen, John Bagterp; Duwig, Christophe

2012-01-01

on exhaust gas emissions. For advanced control, e.g. Model Predictive Control (MPC), of the SCR process, accurate state estimates are needed. We investigate the performance of the ordinary and the extended Kalman filters based on a simple first principle system model. The performance is tested through......Selective catalytic reduction (SCR) of nitrogen oxides (NOx) is a widely applied diesel engine exhaust gas after-treatment technology. For effective NOx removal in a transient operating automotive application, controlled dosing of urea can be used to meet the increasingly restrictive legislations...

A laboratory test setup for in situ measurements of the dielectric properties of catalyst powder samples under reaction conditions by microwave cavity perturbation: set up and initial tests.

Science.gov (United States)

Dietrich, Markus; Rauch, Dieter; Porch, Adrian; Moos, Ralf

2014-09-10

The catalytic behavior of zeolite catalysts for the ammonia-based selective catalytic reduction (SCR) of nitrogen oxides (NOX) depends strongly on the type of zeolite material. An essential precondition for SCR is a previous ammonia gas adsorption that occurs on acidic sites of the zeolite. In order to understand and develop SCR active materials, it is crucial to know the amount of sorbed ammonia under reaction conditions. To support classical temperature-programmed desorption (TPD) experiments, a correlation of the dielectric properties with the catalytic properties and the ammonia sorption under reaction conditions appears promising. In this work, a laboratory test setup, which enables direct measurements of the dielectric properties of catalytic powder samples under a defined gas atmosphere and temperature by microwave cavity perturbation, has been developed. Based on previous investigations and computational simulations, a resonator cavity and a heating system were designed, installed and characterized. The resonator cavity is designed to operate in its TM010 mode at 1.2 GHz. The first measurement of the ammonia loading of an H-ZSM-5 zeolite confirmed the operating performance of the test setup at constant temperatures of up to 300 °C. It showed how both real and imaginary parts of the relative complex permittivity are strongly correlated with the mass of stored ammonia.

Emission reduction from a diesel engine fueled by pine oil biofuel using SCR and catalytic converter

Science.gov (United States)

Vallinayagam, R.; Vedharaj, S.; Yang, W. M.; Saravanan, C. G.; Lee, P. S.; Chua, K. J. E.; Chou, S. K.

2013-12-01

In this work, we propose pine oil biofuel, a renewable fuel obtained from the resins of pine tree, as a potential substitute fuel for a diesel engine. Pine oil is endowed with enhanced physical and thermal properties such as lower viscosity and boiling point, which enhances the atomization and fuel/air mixing process. However, the lower cetane number of the pine oil hinders its direct use in diesel engine and hence, it is blended in suitable proportions with diesel so that the ignition assistance could be provided by higher cetane diesel. Since lower cetane fuels are prone to more NOX formation, SCR (selective catalyst reduction), using urea as reducing agent, along with a CC (catalytic converter) has been implemented in the exhaust pipe. From the experimental study, the BTE (brake thermal efficiency) was observed to be increased as the composition of pine oil increases in the blend, with B50 (50% pine oil and 50% diesel) showing 7.5% increase over diesel at full load condition. The major emissions such as smoke, CO, HC and NOX were reduced by 70.1%, 67.5%, 58.6% and 15.2%, respectively, than diesel. Further, the average emissions of B50 with SCR and CC assembly were observed to be reduced, signifying the positive impact of pine oil biofuel on atmospheric environment. In the combustion characteristics front, peak heat release rate and maximum in-cylinder pressure were observed to be higher with longer ignition delay.

Influence of zeolite structure on the activity and durability of Co-Pd-zeolite catalysts in the reduction of NOx with methane

International Nuclear Information System (INIS)

Pieterse, J.A.Z.; Van den Brink, R.W.; Booneveld, S.; De Bruijn, F.A.

2003-01-01

Selective catalytic reduction of NO with CH 4 was studied over ZSM-5, MOR, FER and BEA zeolite-based cobalt (Co) and palladium (Pd) catalysts in the presence of oxygen and water. As compared to other catalytic systems reported in literature for CH 4 -SCR in the presence of water, zeolite supported Co-Pd combination catalysts are very active and selective. The most active catalysts, based on MOR and ZSM-5, are characterised by well-dispersed Pd ions in the zeolite that activate methane. Wet ion exchange is a good method to achieve high dispersion of Pd provided that it is carried out in a competitive manner. The presence of cobalt (Co 3 O 4 , Co-oxo ions) boosts SCR activity by oxidising NO to NO 2 . The activity of the zeolite-based Co-Pd combination catalysts decreases with prolonged times on stream. The severity of the deactivation was found to be different for different zeolite topologies. The characterisation and evaluation of freshly calcined catalysts and spent catalysts show two things that occur during reaction: (1) zeolite solvated metal cations disappear in favour of (inactive) metal oxides and presumably larger metal entities, i.e. loss of dispersion; (2) loss of crystallinity affiliated with steam-dealumination and the concomitant formation of extra-framework aluminium (EFAL) in the presence of water. Both phenomena strongly depend on the (reaction) temperature. The deactivation of Co-Pd-zeolite resembles the deactivation of Pd-zeolite. Hence, future research could encompass the stabilisation of Pd (cations) in the zeolite pores by exploring additives other than cobalt. For this, detailed understanding on the siting of Pd in zeolites is important

Exhaust gas sensors for NO{sub x} storage catalysts and ammonia SCR systems; Abgassensoren fuer NO{sub x}-Speicherkatalysatoren und Ammoniak-SCR-Systeme

Energy Technology Data Exchange (ETDEWEB)

Moos, R. [Bayreuth Univ. (DE). Bayreuth Engine Research Center (BERC)

2008-07-01

Measuring of the air-to-fuel ratio and/or the exhaust gas oxygen content with the help of an exhaust gas sensor has been established thirty years ago. Whereas the original thimble type lambda probe, which is still shown today in textbooks, is a product of classical ceramic technology, newer sensors are manufactured in planar multilayer technology stemming from electronic technology. This is the basis for additional functionalities like NO{sub x} or ammonia sensitivities. Due to increasing requirements for OBD, the sensor of the future might be a multifunctional device which allows for measuring application specific components as well as lambda in a wide range. From a technical standpoint, it would even today be feasible to manufacture an integrated exhaust gas sensor that can measure ammonia, NO{sub x}, and lambda at the same time. Whether the direct catalyst status diagnosis will become ripe for serial application does not depends only on technical questions and cost considerations but also on the issue whether one is willing to establish a completely novel way of catalyst detection in the exhaust pipe. (orig.)

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...

Regenerative Snubber For GTO-Commutated SCR Inverter

Science.gov (United States)

Rippel, Wally E.; Edwards, Dean B.

1992-01-01

Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.

Operational Choices for Risk Aggregation in Insurance: PSDization and SCR Sensitivity

Directory of Open Access Journals (Sweden)

Xavier Milhaud

2018-04-01

Full Text Available This work addresses crucial questions about the robustness of the PSDization process for applications in insurance. PSDization refers to the process that forces a matrix to become positive semidefinite. For companies using copulas to aggregate risks in their internal model, PSDization occurs when working with correlation matrices to compute the Solvency Capital Requirement (SCR. We examine how classical operational choices concerning the modelling of risk dependence impacts the SCR during PSDization. These operations refer to the permutations of risks (or business lines in the correlation matrix, the addition of a new risk, and the introduction of confidence weights given to the correlation coefficients. The use of genetic algorithms shows that theoretically neutral transformations of the correlation matrix can surprisingly lead to significant sensitivities of the SCR (up to 6%. This highlights the need for a very strong internal control around the PSDization step.

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.

Characteristics of Sucrose Transport through the Sucrose-Specific Porin ScrY Studied by Molecular Dynamics Simulations

Directory of Open Access Journals (Sweden)

Liping eSun

2016-02-01

Full Text Available Sucrose-specific porin (ScrY is a transmembrane protein that allows for the uptake of sucrose under growth-limiting conditions. The crystal structure of ScrY was resolved before by X-ray crystallography, both in its uncomplexed form and with bound sucrose. However, little is known about the molecular characteristics of the transport mechanism of ScrY. To date, there has not yet been any clear demonstration for sucrose transport through the ScrY.Here, the dynamics of the ScrY trimer embedded in a phospholipid bilayer as well as the characteristics of sucrose translocation were investigated by means of atomistic molecular dynamics (MD simulations. The potential of mean force (PMF for sucrose translocation through the pore showed two main energy barriers within the constriction region of ScrY. Energy decomposition allowed to pinpoint three aspartic acids as key residues opposing the passage of sucrose, all located within the L3 loop. Mutation of two aspartic acids to uncharged residues resulted in an accordingly modified electrostatics and decreased PMF barrier. The chosen methodology and results will aid in the design of porins with modified transport specificities.

Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration

Science.gov (United States)

Zhang, Lei; Wen, Xin; Lei, Zhang; Gao, Long; Sha, Xiangling; Ma, Zhenhua; He, Huibin; Wang, Yusu; Jia, Yang; Li, Yonghui

2018-04-01

Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction) was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction), SEM (scanning electron microscope), BET test and transient test. The experiments show that: * The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. * The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO2 is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO2, calcined at 350°Cfor 3h. * The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH3 is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N2, H2O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O2 to regenerate Mn4+.

Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration

Directory of Open Access Journals (Sweden)

Lei Zhang

2018-04-01

Full Text Available Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction, SEM (scanning electron microscope, BET test and transient test. The experiments show that: ① The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. ② The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO2 is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO2, calcined at 350°Cfor 3h. ③ The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH3 is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N2, H2O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O2 to regenerate Mn4+.

A Laboratory Test Setup for in Situ Measurements of the Dielectric Properties of Catalyst Powder Samples under Reaction Conditions by Microwave Cavity Perturbation: Set up and Initial Tests

Directory of Open Access Journals (Sweden)

Markus Dietrich

2014-09-01

Full Text Available The catalytic behavior of zeolite catalysts for the ammonia-based selective catalytic reduction (SCR of nitrogen oxides (NOX depends strongly on the type of zeolite material. An essential precondition for SCR is a previous ammonia gas adsorption that occurs on acidic sites of the zeolite. In order to understand and develop SCR active materials, it is crucial to know the amount of sorbed ammonia under reaction conditions. To support classical temperature-programmed desorption (TPD experiments, a correlation of the dielectric properties with the catalytic properties and the ammonia sorption under reaction conditions appears promising. In this work, a laboratory test setup, which enables direct measurements of the dielectric properties of catalytic powder samples under a defined gas atmosphere and temperature by microwave cavity perturbation, has been developed. Based on previous investigations and computational simulations, a resonator cavity and a heating system were designed, installed and characterized. The resonator cavity is designed to operate in its TM010 mode at 1.2 GHz. The first measurement of the ammonia loading of an H-ZSM-5 zeolite confirmed the operating performance of the test setup at constant temperatures of up to 300 °C. It showed how both real and imaginary parts of the relative complex permittivity are strongly correlated with the mass of stored ammonia.

Low NOx combustion and SCR flow field optimization in a low volatile coal fired boiler.

Science.gov (United States)

Liu, Xing; Tan, Houzhang; Wang, Yibin; Yang, Fuxin; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

2018-08-15

Low NO x burner redesign and deep air staging have been carried out to optimize the poor ignition and reduce the NO x emissions in a low volatile coal fired 330 MW e boiler. Residual swirling flow in the tangentially-fired furnace caused flue gas velocity deviations at furnace exit, leading to flow field unevenness in the SCR (selective catalytic reduction) system and poor denitrification efficiency. Numerical simulations on the velocity field in the SCR system were carried out to determine the optimal flow deflector arrangement to improve flow field uniformity of SCR system. Full-scale experiment was performed to investigate the effect of low NO x combustion and SCR flow field optimization. Compared with the results before the optimization, the NO x emissions at furnace exit decreased from 550 to 650 mg/Nm³ to 330-430 mg/Nm³. The sample standard deviation of the NO x emissions at the outlet section of SCR decreased from 34.8 mg/Nm³ to 7.8 mg/Nm³. The consumption of liquid ammonia reduced from 150 to 200 kg/h to 100-150 kg/h after optimization. Copyright © 2018. Published by Elsevier Ltd.

Study for a stress joint at the top of a SCR (Steel Catenary Risers); Estudo de 'stress joints' para o topo de um SCR (Steel Catenary Risers)

Energy Technology Data Exchange (ETDEWEB)

Siqueira, Elizabeth Frauches Netto; Andrade, Edmundo Queiroz de [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

2008-07-01

Steel Catenary Risers, SCRs, need a top connection that bears the force transmitted to the platform. Essentially, two types of connections exist on the market: flex joint and stress joint (SJ). PETROBRAS has a SCR with top connection of flex joint type installed on one of its platforms; however, the company has been studying SJ as an option out of SCR top connection. A stress joint is a monolithic structure and can be inspected during manufacture and service, without so many difficult. They are metal structures composed of a uniform bore inserted in a tapered wall that increases gradually to support the force coming from the riser. The objective of this paper is to present a SJ sensitivity study for a production SCR supposedly hardwired to a unit of production of the semi-submersible type. The data used is based on real SCR data. For this study, global and local analyses were conducted for some models of stress joints, varying some parameters such as material and dimensions, allowing for the verification of some of the critical points of this type of connection. The results obtained will be shown in graphs and tensions maps to illustrate comparatively the critical points of the models analyzed. (author)

Petroleum residue upgrading with dispersed catalysts. Part 1. Catalysts activity and selectivity

Energy Technology Data Exchange (ETDEWEB)

Panariti, N.; Del Bianco, A.; Del Piero, G. [ENITECNOLOGIE S.p.A, Via Maritano 26, 20097 San Donato Mil. (Italy); Marchionna, M. [SNAMPROGETTI S.p.A, Via Maritano 26, 20097 San Donato Mil. (Italy)

2000-12-04

The results of a study aimed at the identification of the relevant chemical aspects involved in the process of upgrading heavy feedstocks in the presence of dispersed catalysts are discussed. The catalytic activity of different compounds was compared in terms of products yields and quality. Moreover, a detailed and systematic characterization of the catalysts recovered at the end of the reactions was achieved. The experimental work provided quite a large set of data, allowing to investigate the factors that may affect catalyst activity (precursor solubility, rate of activation, degree of dispersion, presence of promoters, etc.). The results of this study demonstrate that the best performances are obtained by the microcrystalline molybdenite generated in situ by oil-soluble precursors. The nature of the organic ligand does not play a very relevant role in influencing the hydrogenation activity. The presence of phosphorus, however, significantly enhances hydrodemetallation, at least in terms of vanadium removal. Bimetallic precursors show a slight synergistic effect towards the hydrodesulfurization reaction. Microsized powdered catalyst precursors have a much lower catalytic activity compared to the oil-soluble ones.

A comparative study on methods of improving SCR for ship detection in SAR image

Science.gov (United States)

Lang, Haitao; Shi, Hongji; Tao, Yunhong; Ma, Li

2017-10-01

Knowledge about ship positions plays a critical role in a wide range of maritime applications. To improve the performance of ship detector in SAR image, an effective strategy is improving the signal-to-clutter ratio (SCR) before conducting detection. In this paper, we present a comparative study on methods of improving SCR, including power-law scaling (PLS), max-mean and max-median filter (MMF1 and MMF2), method of wavelet transform (TWT), traditional SPAN detector, reflection symmetric metric (RSM), scattering mechanism metric (SMM). The ability of SCR improvement to SAR image and ship detection performance associated with cell- averaging CFAR (CA-CFAR) of different methods are evaluated on two real SAR data.

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

Oxidative desulfurization of synthetic diesel using supported catalysts. Part 3. Support effect on vanadium-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Cedeno-Caero, Luis; Gomez-Bernal, Hilda; Fraustro-Cuevas, Adriana; Guerra-Gomez, Hector D.; Cuevas-Garcia, Rogelio [UNICAT, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria 04510, Mexico D.F. (Mexico)

2008-04-15

Oxidesulfurization (ODS) of benzothiophenic compounds prevailing in diesel was conducted with hydrogen peroxide in presence of various catalysts, using a model diesel and actual diesel fuel. ODS activities of dibenzothiophenes (DBTs) in hexadecane for a series of V{sub 2}O{sub 5} catalysts supported on alumina, titania, ceria, niobia and silica, were evaluated. Results show that the oxidation activity of DBTs depends on the support used. It was observed that the sulfone yield is not proportional to textural properties or V content. For all catalysts, ODS of benzothiophene (BT), dibenzothiophene (DBT), 4-methyl dibenzothiophene (4-MDBT) and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) decreased in the following order: DBT > 4-MDBT > 4,6-DMDBT > BT. This trend does not depend on the catalyst used or the textural properties of the catalysts and supports. In presence of indole ODS activities diminish, except with catalysts supported on alumina-titania mixed oxide, whereas with V{sub 2}O{sub 5}/TiO{sub 2} catalyst the performance is the highest. ODS of Mexican diesel fuel was carried out in presence of this catalyst and S level was diminished in about 99%. (author)

SCR-1: Design and construction of a small modular stellarator for magnetic confinement of plasma

International Nuclear Information System (INIS)

Barillas, L; Vargas, V I; Alpizar, A; Asenjo, J; Carranza, J M; Cerdas, F; Gutiérrez, R; Monge, J I; Mora, J; Morera, J; Peraza, H; Rojas, C; Rozen, D; Saenz, F; Sánchez, G; Sandoval, M; Trimiño, H; Umaña, J; Villegas, L F; Queral, V

2014-01-01

This paper describes briefly the design and construction of a small modular stellarator for magnetic confinement of plasma, called Stellarator of Costa Rica 1, or SCR-1; developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica, PlasmaTEC. The SCR-1 is based on the small Spanish stellarator UST 1 , created by the engineer Vicente Queral. The SCR-1 will employ stainless steel torus-shaped vacuum vessel with a major radius of 460.33 mm and a cross section radius of 110.25 mm. A typical SCR-1 plasma will have an average radius 42.2 mm and a volume of 8 liters (0.01 m 3 ), and an aspect ratio of 5.7. The magnetic resonant field will be 0.0878 T, and a period of 2 (m=2) with a rotational transform of 0.3. The magnetic field will be provided by 12 modular coils, with 8 turns each, with an electrical current of 8704 A per coil (1088 A per turn of each coil). This current will be fed by a bank of cell batteries. The plasma will be heated by ECRH with magnetrons of a total power of 5 kW, in the first harmonic at 2.45 GHz. The expected electron temperature and density are 15 eV and 10 17 m −3 respectively with an estimated confinement time of 7.30 x 10 −4 ms. The initial diagnostics on the SCR-1 will consist of a Langmuir probe, a heterodyne microwave interferometer, and a field mapping system. The first plasma of the SCR-1 is expected at the end of 2011.

Experimental demonstration of a new model-based SCR control strategy for cleaner heavy-duty diesel engines

NARCIS (Netherlands)

Willems, F.P.T.; Cloudt, R.P.M.

2011-01-01

Selective catalytic reduction (SCR) is a promising diesel aftertreatment technology that enables low nitrogen oxides (NOx) tailpipe emissions with relatively low fuel consumption. Future emission legislation is pushing the boundaries for SCR control systems to achieve high NOx conversion within a

Deactivation-resistant catalyst for selective catalyst reduction of NOx

DEFF Research Database (Denmark)

2011-01-01

The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least...... one metal oxide. In another aspect the present invention relates to the use of said catalyst and to a method of producing said catalyst. In addition, the present invention relates to a method of treating an catalyst for conferring thereon an improved resistance to alkali poisoning....

A particle filter for ammonia coverage ratio and input simultaneous estimations in Diesel-engine SCR system.

Science.gov (United States)

Sun, Kangfeng; Ji, Fenzhu; Yan, Xiaoyu; Jiang, Kai; Yang, Shichun

2018-01-01

As NOx emissions legislation for Diesel-engines is becoming more stringent than ever before, an aftertreatment system has been widely used in many countries. Specifically, to reduce the NOx emissions, a selective catalytic reduction(SCR) system has become one of the most promising techniques for Diesel-engine vehicle applications. In the SCR system, input ammonia concentration and ammonia coverage ratio are regarded as essential states in the control-oriental model. Currently, an ammonia sensor placed before the SCR Can is a good strategy for the input ammonia concentration value. However, physical sensor would increase the SCR system cost and the ammonia coverage ratio information cannot be directly measured by physical sensor. Aiming to tackle this problem, an observer based on particle filter(PF) is investigated to estimate the input ammonia concentration and ammonia coverage ratio. Simulation results through the experimentally-validated full vehicle simulator cX-Emission show that the performance of observer based on PF is outstanding, and the estimation error is very small.

Dynamic flow control strategies of vehicle SCR Urea Dosing System

Science.gov (United States)

Lin, Wei; Zhang, Youtong; Asif, Malik

2015-03-01

Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine's operating conditions. That will lead to low NO X conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between -8% and 10% to -4% and 2% and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms. The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NO X emission remains almost unchanged. The trade-off between NO X conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine's operating conditions quickly.

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.

Process identification of the SCR system of coal-fired power plant for de-NOx based on historical operation data.

Science.gov (United States)

Li, Jian; Shi, Raoqiao; Xu, Chuanlong; Wang, Shimin

2018-05-08

The selective catalytic reduction (SCR) system, as one principal flue gas treatment method employed for the NO x emission control of the coal-fired power plant, is nonlinear and time-varying with great inertia and large time delay. It is difficult for the present SCR control system to achieve satisfactory performance with the traditional feedback and feedforward control strategies. Although some improved control strategies, such as the Smith predictor control and the model predictive control, have been proposed for this issue, a well-matched identification model is essentially required to realize a superior control of the SCR system. Industrial field experiment is an alternative way to identify the SCR system model in the coal-fired power plant. But it undesirably disturbs the operation system and is costly in time and manpower. In this paper, a process identification model of the SCR system is proposed and developed by applying the asymptotic method to the sufficiently excited data, selected from the original historical operation database of a 350 MW coal-fired power plant according to the condition number of the Fisher information matrix. Numerical simulations are carried out based on the practical historical operation data to evaluate the performance of the proposed model. Results show that the proposed model can efficiently achieve the process identification of the SCR system.

L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana.

Science.gov (United States)

Wang, Zhen; Mao, Jie-Li; Zhao, Ying-Jun; Li, Chuan-You; Xiang, Cheng-Bin

2015-02-01

L-Cysteine plays a prominent role in sulfur metabolism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PINs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and SCR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth. © 2014 Institute of Botany, Chinese Academy of Sciences.

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

Uniformly active phase loaded selective catalytic reduction catalysts (V_2O_5/TNTs) with superior alkaline resistance performance

International Nuclear Information System (INIS)

Wang, Haiqiang; Wang, Penglu; Chen, Xiongbo; Wu, Zhongbiao

2017-01-01

Highlights: • VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3. • Ion-exchange reaction occurs between VOSO_4 and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO_4-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH_4VO_3 and VOSO_4) were used to synthesize deNO_x catalysts. The results showed that VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V"5"+/V"4"+ redox cycles and superior oxygen mobility were achieved. Besides, VOSO_4-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V_2O_5/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

Does NGAL reduce costs? A cost analysis of urine NGAL (uNGAL) & serum creatinine (sCr) for acute kidney injury (AKI) diagnosis.

Science.gov (United States)

Parikh, Amay; Rizzo, John A; Canetta, Pietro; Forster, Catherine; Sise, Meghan; Maarouf, Omar; Singer, Eugenia; Elger, Antje; Elitok, Saban; Schmidt-Ott, Kai; Barasch, Jonathon; Nickolas, Thomas L

2017-01-01

Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a sensitive and specific diagnostic test for acute kidney injury (AKI) in the Emergency Department (ED), but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr) would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone. A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs. uNGAL plus sCr (uNGAL+sCr). A cost minimization analysis was performed to determine total expected costs for patients with AKI. uNGAL test characteristics were validated with eight-hundred forty-nine patients with sCr ≥1.5 from a completed study of 1635 patients recruited from EDs at two U.S. hospitals from 2007-8. Biomarker test, AKI work-up, and diagnostic imaging costs were incorporated. For a hypothetical cohort of 10,000 patients, the model predicted that the expected costs were $900 per patient (pp) in the sCr arm and $950 in the uNGAL+sCr arm. uNGAL+sCr resulted in 1,578 fewer patients with delayed diagnosis and treatment than sCr alone (2,013 vs. 436 pts) at center 1 and 1,973 fewer patients with delayed diagnosis and treatment than sCr alone at center 2 (2,227 vs. 254 patients). Although initial evaluation costs at each center were $50 pp higher in with uNGAL+sCr, total costs declined by $408 pp at Center 1 and by $522 pp at Center 2 due to expected reduced delays in diagnosis and treatment. Sensitivity analyses confirmed savings with uNGAL + sCr for a range of cost inputs. Using uNGAL with sCr as a clinical diagnostic test for AKI may improve patient management and reduce expected costs. Any cost savings would likely result from avoiding delays in diagnosis and treatment and from avoidance of unnecessary testing in patients given a false positive AKI diagnosis by use of sCr alone.

Does NGAL reduce costs? A cost analysis of urine NGAL (uNGAL & serum creatinine (sCr for acute kidney injury (AKI diagnosis.

Directory of Open Access Journals (Sweden)

Amay Parikh

Full Text Available Urine neutrophil gelatinase-associated lipocalin (uNGAL is a sensitive and specific diagnostic test for acute kidney injury (AKI in the Emergency Department (ED, but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone.A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs. uNGAL plus sCr (uNGAL+sCr. A cost minimization analysis was performed to determine total expected costs for patients with AKI. uNGAL test characteristics were validated with eight-hundred forty-nine patients with sCr ≥1.5 from a completed study of 1635 patients recruited from EDs at two U.S. hospitals from 2007-8. Biomarker test, AKI work-up, and diagnostic imaging costs were incorporated.For a hypothetical cohort of 10,000 patients, the model predicted that the expected costs were $900 per patient (pp in the sCr arm and $950 in the uNGAL+sCr arm. uNGAL+sCr resulted in 1,578 fewer patients with delayed diagnosis and treatment than sCr alone (2,013 vs. 436 pts at center 1 and 1,973 fewer patients with delayed diagnosis and treatment than sCr alone at center 2 (2,227 vs. 254 patients. Although initial evaluation costs at each center were $50 pp higher in with uNGAL+sCr, total costs declined by $408 pp at Center 1 and by $522 pp at Center 2 due to expected reduced delays in diagnosis and treatment. Sensitivity analyses confirmed savings with uNGAL + sCr for a range of cost inputs.Using uNGAL with sCr as a clinical diagnostic test for AKI may improve patient management and reduce expected costs. Any cost savings would likely result from avoiding delays in diagnosis and treatment and from avoidance of unnecessary testing in patients given a false positive AKI diagnosis by use of sCr alone.

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.

SCR series switch and impulse crowbar at the Lawrence Berkeley Laboratory for CTR neutral beam source development

International Nuclear Information System (INIS)

Franck, J.V.; Arthur, A.A.; Brusse, L.A.; Low, W.

1977-10-01

The series switch is designed to operate at 120kV and pass 65A for 0.5 sec every 30 sec on the Lawrence Berkeley Laboratory CTR Neutral Beam Source Test Stand IIIB. The series switch consists of 400 individual SCR circuits connected in series and is turned on by a simple system of cascaded pulse transformers with multiple single turn secondaries each driving the individual SCR gates. It is turned off by an SCR impulse crowbar that momentarily shorts the power supply allowing the series switch to recover. The SCR switch has been tested in the impulse crowbar configuration and will reliably commutate up to 90A at 120kV. The series switch and impulse crowbar are now in service in Test Stand IIIB. A series switch and impulse crowbar similar in concept is routinely powering a 10 x 10 cm source at 150kV, 20A, 0.5 sec with a 1% duty cycle on the Lawrence Berkeley Laboratory CTR NSB Test Stand IIIA

Deactivation of V2O5-WO3-TiO2 SCR catalyst at a biomass-fired combined heat and power plant

DEFF Research Database (Denmark)

Zheng, Yuanjing; Jensen, Anker; Johnsson, Jan Erik

2005-01-01

. Three catalyst elements were exposed at 350 °C, and one element was exposed at 250 °C for comparison. The catalyst activity was measured in the reactor at the exposure temperature by addition of NH3 and extra NO. The activity, in terms of a first-order rate constant, dropped by 52% after about 1140 h...... indicating a very fast deactivation compared to coal firing. It was also found that the reactor temperature was not of importance for the deactivation rate. SEM-EDX analysis showed that particle deposition and pore blocking contributed to the deactivation by decreasing the diffusion rate of NO and NH3...... decreased as a function of exposure time, which reveals that Brøndsted acid sites had reacted with potassium compounds and thereby rendered inactive. When washed by 0.5 M H2SO4 the regenerated catalyst regains a higher activity than that of the fresh catalyst at temperatures higher than 300 °C, but even...

The addition of bio-butanol to GHGenius and a review of the GHG emissions from diesel engines with urea SCR

International Nuclear Information System (INIS)

2007-01-01

The GHGenius model was developed to analyze the emissions of contaminants associated with the use and production of traditional and alternative transportation fuels. Over 140 vehicle and fuel combinations can be used with the model, which is continuously updated with new information on existing processes, new pathways, and new features. This paper provided details of the addition of a butanol production pathway and a urea system for heavy duty diesel engines. Butanol has recently been proposed as a gasoline additive for use with ethanol or as an alternative to ethanol in low-level gasoline blends. A corn to butanol pathway for low level blends was considered as the most appropriate pathway for North American applications. Estimates of energy required were made based on economic assessments and the estimated cost of energy at the time the estimates were made. In the second approach, an ethanol process model was modified to have the same water and feedstock ratios as a butanol feedstock. Total energy balances for the traditional butanol production system were poor due to the large energy requirement in the butanol production process. Low butanol concentrations were attributed to butanol toxicity to fermentation organisms. However, energy credits from co-products were large compared to many other pathways, and were attributed to the energy intensity of hydrogen and acetone. This report also provided details of selective catalytic reduction (SCR) processes that used ammonia or urea with a catalyst to produce water and gaseous nitrogen. Total energy balances and emissions impacts on the full lifecycle of SCR systems for diesel engines were provided. 13 refs., 17 tabs., 8 figs

Selective catalytic reduction of NO{sub x} with NH{sub 3} over iron-cerium-tungsten mixed oxide catalyst prepared by different methods

Energy Technology Data Exchange (ETDEWEB)

Xiong, Zhi-bo, E-mail: xzb328@163.com [School of Energy and Power Engineering, University of Shanghai for Science & Technology, Shanghai 200093 (China); Collaborative Innovation Research Institute, University of Shanghai for Science & Technology, Shanghai 200093 (China); Shanghai Power Equipment Research Institute, Shanghai 200240 (China); Liu, Jing; Zhou, Fei; Liu, Dun-yu; Lu, Wei [School of Energy and Power Engineering, University of Shanghai for Science & Technology, Shanghai 200093 (China); Jin, Jing [School of Energy and Power Engineering, University of Shanghai for Science & Technology, Shanghai 200093 (China); Collaborative Innovation Research Institute, University of Shanghai for Science & Technology, Shanghai 200093 (China); Ding, Shi-fa [Shanghai Power Equipment Research Institute, Shanghai 200240 (China)

2017-06-01

Highlights: • Iron-cerium-tungsten mixed oxide catalysts were prepared through three different methods. • The effect of preparation methods on the NH{sub 3}-SCR activity and the surface structure properties of catalyst were investigated. • Iron-cerium-tungsten mixed oxide prepared through microwave irradiation assistant critic acid sol-gel shows higher NH{sub 3}-SCR activity. - Abstract: A series of magnetic Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z} catalysts were synthesized by three different methods(Co-precipitation(Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-CP), Hydrothermal treatment assistant critic acid sol-gel method(Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-HT) and Microwave irradiation assistant critic acid sol-gel method(Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-MW)), and the catalytic activity was evaluated for selective catalytic reduction of NO with NH{sub 3}. The catalyst was characterized by XRD, N{sub 2} adsorption-desorption, XPS, H{sub 2}-TPR and NH{sub 3}-TPD. Among the tested catalysts, Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-MW shows the highest NO{sub x} conversion over per gram in unit time with NO{sub x} conversion of 60.8% at 350 °C under a high gas hourly space velocity of 1,200,000 ml/(g h). Different from Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-CP catalyst, there exists a large of iron oxide crystallite(γ-Fe{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3}) scattered in Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z} catalysts prepared through hydrothermal treatment or microwave irradiation assistant critic acid sol-gel method, and higher iron atomic concentration on their surface. And Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-MW shows higher surface absorbed oxygen concentration and better dispersion compared with Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-HT catalyst. These features were favorable for the high catalytic performance of NO reduction with NH{sub 3} over Fe{sub 0.85}Ce{sub 0.10}W{sub 0.05}O{sub z}-MW catalyst.

EMISSION REDUCTION FROM A DIESEL ENGINE FUELED BY CERIUM OXIDE NANO-ADDITIVES USING SCR WITH DIFFERENT METAL OXIDES COATED CATALYTIC CONVERTER

Directory of Open Access Journals (Sweden)

B. JOTHI THIRUMAL

2015-11-01

Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in nanoparticle form on the major physiochemical properties and the performance of diesel. The fuel is modified by dispersing the catalytic nanoparticle by ultrasonic agitation. The physiochemical properties of sole diesel fuel and modified fuel are tested with ASTM standard procedures. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Cerium oxide acts as an oxygen-donating catalyst and provides oxygen for the oxidation of CO during combustion. The active energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall which results in reduction in HC emission by 56.5%. Furthermore, a low-cost metal oxide coated SCR (selective catalyst reduction, using urea as a reducing agent, along with different types of CC (catalytic converter, has been implemented in the exhaust pipe to reduce NOx. It was observed that a reduction in NOx emission is 50–60%. The tests revealed that cerium oxide nanoparticles can be used as an additive in diesel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

Sulfur poisoning and regeneration of the Ag/γ-Al2O3 catalyst for H2-assisted SCR of NOx by ammonia

DEFF Research Database (Denmark)

Doronkin, Dmitry E.; Khan, Tuhin Suvra; Bligaard, Thomas

2012-01-01

Sulfur poisoning and regeneration mechanisms for a 2% Ag/γ-Al2O3 catalyst for the H2-assisted selective catalytic reduction of NOx by NH3 are investigated. The catalyst has medium sulfur tolerance at low temperatures, however a good capability of regeneration at 670°C under lean conditions when H...

Low cost SCR lamp driver indicates contents of digital computer registers

Science.gov (United States)

Cliff, R. A.

1967-01-01

Silicon Controlled Rectifier /SCR/ lamp driver is adapted for use in integrated circuit digital computers where it indicates the contents of the various registers. The threshold voltage at which visual indication begins is very sharply defined and can be adjusted to suit particular system requirements.

Chemical deactivation of Ag/Al2O3 by sulphur for the selective reduction of NOx using hydrocarbons

International Nuclear Information System (INIS)

Houel, Valerie; Millington, Paul; Pollington, Stephen; Poulston, Stephen; Rajaram, Raj R.; Tsolakis, Athanasios

2006-01-01

The hydrocarbon-SCR activity of Ag/Al 2 O 3 catalysts is severely deactivated after low temperature (350 o C) sulphur ageing in the form of SO 2 exposure. Catalysts aged with SO 2 , NO and hydrocarbon present accumulate a significantly larger amount of SO 4 2- than those aged in the presence of only O 2 , H 2 O and SO 2 when exposed to an equivalent amount of S. Following sulphation of the catalyst most of the sulphur can be removed by a high temperature (600 o C) treatment in the reaction gas. Regeneration in the absence of hydrocarbon is ineffective. The hydrocarbon-SCR activity of the sulphated catalyst using model hydrocarbons such as n-C 8 H 18 can be restored after a high temperature pre-treatment in the reaction gases. However this desulphation process fails to regenerate the hydrocarbon-SCR activity when diesel fuel is used in the activity test. TPR studies show that a major fraction of the sulphur species present in the catalyst is removed by such pre-treatment, but the slight residual amount of sulphur is sufficient to inhibit the activation of the diesel fuel on the Ag catalyst. The nature of the hydrocarbon species present for the hydrocarbon-SCR reaction and during the regeneration strongly influences the activity. In general aromatics such as C 7 H 8 are less effective for reducing NO x and regenerating the sulphated catalyst. (author)

Importance of the Cu oxidation state for the SO2-poisoning of a Cu-SAPO-34 catalyst in the NH3-SCR reaction

DEFF Research Database (Denmark)

Hammershøi, Peter S.; Vennestrøm, Peter N. R.; Falsig, Hanne

2018-01-01

behavior and mechanisms of a Cu-SAPO-34 catalyst were studied with reactor tests and DFT calculations. Exposure of the catalyst to two different SO2 concentrations and durations, but with the same total SO2 exposure, calculated as the product of partial pressure of SO2 and exposure time, lead to the same...... degree of deactivation. Exposure of the Cu-SAPO-34 catalyst to SO2 in the presence and absence of NO and NH3 at different temperatures between 200–600 °C showed different trends for the deactivation. Below 400 °C, the S/Cu ratio on the catalyst increased with temperature in absence of NO and NH3, while...... showing that SO2 and SO3, which is possibly formed by oxidation of SO2 over Cu sites, interact similar with Cu in Cu-SAPO-34 and Cu-SSZ-13....

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.

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.

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.

Selective catalytic reduction of NOx and N{sub 2}O by NH{sub 3} over Fe-FER; Developpement d'un traitement catalytique combine des NOx et de N{sub 2}O par NH{sub 3} sur Fe-Fer

Energy Technology Data Exchange (ETDEWEB)

Kieger, St. [Grande Paroisse, 76 - Grand-Quevilly (France); Navascues, L.; Gry, Ph. [Grande Paroisse, 92 - Paris la Defense (France)

2001-07-01

The emission of nitrogen oxides from anthropogenic activities is a major environmental issue. N{sub 2}O is taking part to the global warming and depletion of the stratospheric ozone layer, and NOx to acid rains. At the Kyoto Conference in 1997, the European Union committed itself to reduce by 8% the release of greenhouse gases at the horizon 2010. The selective catalytic reduction (SCR) of NOx by NH{sub 3} is nowadays the main control technology for the emissions from nitric acid plant. Therefore, Grande Paroisse and IRMA have developed a new catalyst (Fe-FER) for the SCR of N{sub 2}O by NH{sub 3}. The catalyst was evaluated in a pilot plant and in the same operating conditions than a DeNOx catalyst. At a space velocity of 9000 to 12000 h{sup -1}, a decomposition of 50% of N{sub 2}O was achieved at 440 deg C. Moreover for the same decomposition level, the temperature could be shifted to 390 deg C by adding ammonia, and the complete reduction of NOx was also observed. This new catalyst is rather bi-functional. Also after months of using, the catalyst did not show major loss of activity nor mechanical strength. (authors)

SCR96, a small cysteine-rich secretory protein of Phytophthora cactorum, can trigger cell death in the Solanaceae and is important for pathogenicity and oxidative stress tolerance.

Science.gov (United States)

Chen, Xiao-Ren; Li, Yan-Peng; Li, Qi-Yuan; Xing, Yu-Ping; Liu, Bei-Bei; Tong, Yun-Hui; Xu, Jing-You

2016-05-01

Peptides and small molecules produced by both the plant pathogen Phytophthora and host plants in the apoplastic space mediate the relationship between the interplaying organisms. Various Phytophthora apoplastic effectors, including small cysteine-rich (SCR) secretory proteins, have been identified, but their roles during interaction remain to be determined. Here, we identified an SCR effector encoded by scr96, one of three novel genes encoding SCR proteins in P. cactorum with similarity to the P. cactorum phytotoxic protein PcF. Together with the other two genes, scr96 was transcriptionally induced throughout the developmental and infection stages of the pathogen. These genes triggered plant cell death (PCD) in the Solanaceae, including Nicotiana benthamiana and tomato. The scr96 gene did not show single nucleotide polymorphisms in a collection of P. cactorum isolates from different countries and host plants, suggesting that its role is essential and non-redundant during infection. Homologues of SCR96 were identified only in oomycetes, but not in fungi and other organisms. A stable protoplast transformation protocol was adapted for P. cactorum using green fluorescent protein as a marker. The silencing of scr96 in P. cactorum caused gene-silenced transformants to lose their pathogenicity on host plants and these transformants were significantly more sensitive to oxidative stress. Transient expression of scr96 partially recovered the virulence of gene-silenced transformants on plants. Overall, our results indicate that the P. cactorum scr96 gene encodes an important virulence factor that not only causes PCD in host plants, but is also important for pathogenicity and oxidative stress tolerance. © 2015 BSPP AND JOHN WILEY & SONS LTD.

Analysis of the offshore installations regulations 2005 (SCR05r12) within Brazilian reality; Analise da regulacao das instalacoes offshore 2005 (SCR05r12) dentro da realidade brasileira

Energy Technology Data Exchange (ETDEWEB)

Nalvarte, Gladys; Storch, Rafael; Araujo, Pedro; Oliveira, Luiz Fernando [Det Norske Veritas (Brazil)

2008-07-01

The main motivation for the present study is the modifications presented in the guidance Offshore Installations (Safety Case) Regulations 2005 (SCR05 r12), released by HSE, in relation to the Offshore Installation Regulation 1992, SCR92. A critical analysis of the new regulation issued by HSE is developed and conclusions are obtained. A cost-benefit approach applied to the Quantitative Risk Analysis (QRA), using computational fluid dynamics (CFD) techniques, is suggested. Thereby, a method to identify the mitigation measures that most reduces the risks with the minimum cost is obtained. On the other hand, this new QRA approach combined with a cost benefit analysis is intended to have a total cost diminished. In this case, the cost of the new QRA study is dependant on the number of reevaluations needed to determine the mitigation measures to be applied. (author)

Uniformly active phase loaded selective catalytic reduction catalysts (V{sub 2}O{sub 5}/TNTs) with superior alkaline resistance performance

Energy Technology Data Exchange (ETDEWEB)

Wang, Haiqiang; Wang, Penglu [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China); Chen, Xiongbo [South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655 (China); Wu, Zhongbiao, E-mail: zbwu@zju.edu.cn [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China)

2017-02-15

Highlights: • VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}. • Ion-exchange reaction occurs between VOSO{sub 4} and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO{sub 4}-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH{sub 4}VO{sub 3} and VOSO{sub 4}) were used to synthesize deNO{sub x} catalysts. The results showed that VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V{sup 5+}/V{sup 4+} redox cycles and superior oxygen mobility were achieved. Besides, VOSO{sub 4}-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V{sub 2}O{sub 5}/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

Selective Catalytic Reduction of NO with NH3 Over V-MCM-41 Catalyst.

Science.gov (United States)

Kwon, Woo Hyun; Park, Sung Hoon; Kim, Ji Man; Park, Su Bin; Jung, Sang-Chul; Kim, Sang Chai; Jeon, Jong-Ki; Park, Young-Kwon

2016-02-01

V-MCM-41, a mesoporous catalyst doped with V2O5, was applied for the first time to the removal of atmospheric NO. The quantity of V2O5 added was 10 wt% and 30 wt%. The characteristics of the synthesized catalysts were examined using XRD, N2 soprtion, and NH3-TPD. With increasing quantity of V2O5 added, specific surface area decreased and pore size increased. When the quantity of V2O5 was 10 wt%, the MCM-41 structure was retained, whereas considerable collapse of mesoporous structure was observed when 30 wt% V2O5 was added. The examination of acid characteristics using NH3-TPD showed that 30 wt% V-MCM-41 had the higher NH3 adsorption ability, implying that it would exhibit high activity for NH3 SCR reaction. In the NO removal experiments, 30 wt% V-MCM-41 showed much higher NO removal efficiency than 10 wt% V-MCM-41, which was attributed to its high NH3 adsorption ability.

On the importance of the phase distribution and acidity of VOx-ZrO2-SO4-sepiolite catalysts for the NH3-SCR process in relation to biomass fueled power plants

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren Birk; Riisager, Anders

A series of V2O5-ZrO2-SO42- - sepiolite mixtures were extruded, calcined and characterized. NH3-SCR activity was related to the phase distribution of the agglomerant and active VOX-ZrO2-SO42- phase, as well as the acidity of the composite material. Electrophoretic migration results showed...

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

The influence of a silica pillar in lamellar tetratitanate for selective catalytic reduction of NO{sub x} using NH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Nogueira da Cunha, Beatriz; Gonçalves, Alécia Maria; Gomes da Silveira, Rafael [Institute of Chemistry, Federal University of Goiás, C. Postal 131, CEP 74001-970 Goiânia, GO (Brazil); Urquieta-González, Ernesto A. [Laboratory of Applied Catalysis, Department of Chemical Engineering, Federal University of Sao Carlos, Rodovia Washington Luis Km 235, C. Postal 676, CEP 13565-905 São Carlos, SP (Brazil); Magalhães Nunes, Liliane, E-mail: lilianemnunes@gmail.com [Institute of Chemistry, Federal University of Goiás, C. Postal 131, CEP 74001-970 Goiânia, GO (Brazil)

2015-01-15

Highlights: • Potassium ions significantly affected the SCR. • The introduction of silica in the catalyst promotes the NH{sub 3}-SCR reaction. • The catalysts activities were not significantly influenced by SO{sub 2} addition. - Abstract: Silica-pillared layered titanate (SiO{sub 2}–Ti{sub 4}O{sub 9}) was prepared by intercalating organosilanes into the interlayers of a layered K{sub 2}Ti{sub 4}O{sub 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{sub 2}-TPR), nuclear magnetic resonance ({sup 29}Si NMR), and infrared spectroscopy (FT-IR). Reduction of NO by NH{sub 3} was studied in a fixed-bed reactor packed with the catalysts and fed a mixture comprising 1% NH{sub 3}, 1% NO, 10% O{sub 2}, and 34 ppm SO{sub 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{sub 2}Ti{sub 4}O{sub 9}, significantly affected the reaction and level of vanadium species reduction. The catalyst (1VSiT) with 1 wt% vanadium impregnated on the SiO{sub 2}–Ti{sub 4}O{sub 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{sub 3} adsorption demonstrate that introduction of silica in the catalyst promotes the NH{sub 3}-SCR reaction. More importantly, 2VSiT and 1VSiT were strongly resistant to SO{sub 2} poisoning.

Catalytic Oxidation of Phenol over Zeolite Based Cu/Y-5 Catalyst: Part 1: Catalyst Preparation and Characterization

Directory of Open Access Journals (Sweden)

K. Maduna Valkaj

2015-01-01

Full Text Available The necessity to remove organic pollutants from the industrial wastewater streams has forced the development of new technologies that can produce better results in terms of pollutant removal and process efficiency in combination with low investment and operating costs. One of the new emerging processes with a potential to fulfil these demands is catalytic wet peroxide oxidation, commonly known as the CWPO process. The oxidative effect of the hydrogen peroxide is intensified by the addition of a heterogeneous catalyst that can reduce the operating conditions to atmospheric pressure and temperatures below 383 K. Zeolites, among others, are especially appealing as catalysts for selective oxidation processes due to their unique characteristics such as shape selectivity, thermal and chemical stability, and benign effect on nature and the living world. In this work, catalytic activity, selectivity and stability of Cu/Y-5 zeolite in phenol oxidation with hydrogen peroxide was examined. Catalyst samples were prepared by ion exchange method of the protonic form of commercial zeolite. The catalysts were characterized with powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and AAS elemental analysis, while the adsorption techniques were used for the measurement of the specific surface area. The catalytic tests were carried out in a stainless steel Parr reactor in batch operation mode at the atmospheric pressure and in the temperature range from 323 to 353 K. The catalyst was prepared in powdered form and the mass fraction of the active metal component on the zeolite was 3.46 %. The initial concentration of phenol solution was equal to 0.01 mol dm−3 and the concentration of hydrogen peroxide ranged from 0.01 to 0.10 mol dm−3. The obtained experimental data was tested to a proposed kinetic model for phenol oxidation r = k1 cF cVP and hydrogen peroxide decomposition rHP = k2 cHP. The kinetic parameters were estimated using the Nelder

An SCR inverter for electric vehicles

Science.gov (United States)

Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.

1980-01-01

An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.

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…

An engineering approach to the design and construction of a small modular stellarator for magnetic confinement of plasma. SCR-1

International Nuclear Information System (INIS)

Barillas, Laura; Vargas, V. Iván; Alpízar, Asdrúval

2011-01-01

This paper briefly describes the design and construction of Stellarator of Costa Rica 1 (SCR-1) from an engineering perspective. SCR-1 is a small modular Stellarator for magnetic confinement of plasma developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica (ITCR). The SCR-1 is based on the small Spanish Stellarator UST 1 (Ultra Small Torus 1), created by engineer Vicente Queral. Some of the characteristics of the SCR-1 are the following: it will be a 2-field period modular stellarator with an aspect ratio ≈ 6; low shear configuration with core and edge rotational transform equal to 0.32 and 0.28; it will employ stainless steel torus-shaped vacuum vessel which will hold a plasma with an average radius a ≈ 42.2 mm, a volume of 8 liters (0.008 m 3 ), and major radius R = 238 mm. This plasma will be confined by a magnetic field (B ≈ 90 mT) given by 12 modular coils with 12 turns each, carrying a current of 725 A per turn providing a total toroidal field (TF) current of 8.7 kA-turn per coil. The coils will be supplied by a bank of cell batteries of 120 V. Typical length of the plasma pulse will be between 4 s to 10 s. The plasma heating will be achieved by electron cyclotron radio-frequency (ECH) from two magnetrons providing a total power of 5 kW, at a frequency of 2.45 GHz corresponding to the first harmonic (B 0 = 87.8 mT). The expected electron temperature and density are 15 eV and 7x10 16 m -3 respectively. The initial diagnostics on the SCR-1 will consist of a Langmuir probe with a displacement system, a heterodyne microwave interferometer (frequency of 28 GHz, corresponding to a wavelength of λ = 10.71 mm). The first plasma of the SCR-1 is expected at the beginning of 2012. (author)

Hydroprocessing catalysts utilization and regeneration schemes

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

The catalyst reactor inventory represents an important part of the cost of hydroprocessing operation. The selection of a suitable catalyst and reactor is influenced by feedstock properties. Processes ensuring an uninterrupted operation during catalyst addition and withdrawal are preferred for processing high asphaltene and metal content feedstocks. The spent catalyst can be regenerated and returned to the operation if the extent of its deactivation is not high. The regeneration may be performed either in-situ or off-site. The former is suitable for fixed bed reactors whereas the catalyst from ebullated bed reactors must be regenerated off-site. The regeneration of spent catalysts heavily loaded with metals such as V, Ni and Fe may not be economic. Such catalysts may be suitable for metal reclamation. An environmentally safe method for catalyst disposal must be found if neither regeneration nor metal reclamation from spent catalysts can be performed.

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

A method of formal requirements analysis for NPP I and C systems based on object-oriented visual modeling with SCR

International Nuclear Information System (INIS)

Koo, S. R.; Seong, P. H.

1999-01-01

In this work, a formal requirements analysis method for Nuclear Power Plant (NPP) I and C systems is suggested. This method uses Unified Modeling Language (UML) for modeling systems visually and Software Cost Reduction (SCR) formalism for checking the system models. Since object-oriented method can analyze a document by the objects in a real system, UML models that use object-oriented method are useful for understanding problems and communicating with everyone involved in the project. In order to analyze the requirement more formally, SCR tabular notations is converted from UML models. To help flow-through from UML models to SCR specifications, additional syntactic extensions for UML notation and a converting procedure are defined. The combined method has been applied to Dynamic Safety System (DSS). From this application, three kinds of errors were detected in the existing DSS requirements

Catalytic reduction of NO{sub x}. Final report; Katalytisk Reduktion av NO{sub x}. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Khodayari, Raziyeh; Odenbrand, Ingemar [Lund Univ. (Sweden). Chemical Engineering II

2002-02-01

This report is intended to show the work regarding the SCR technique performed at Chemical Engineering II, Lund Inst. of Tech. since the start in 1982. The emphasis is on work performed the last 7 years which deals with deactivation and regeneration of SCR catalysts. In chapter 1 a short general introduction to the SCR technique is given. Chapter 2 describes the work performed up to 1995. It shows the kinetics for the reaction between NO and NH{sub 3}, reactions between NO{sub 2} and NH{sub 3} as well as patents for a new process for cleaning flue gases based on our research results. Later work on using zeolites as catalysts for the reduction and for the oxidation of NO was presented. Then a series of characterisations were performed on model catalysts consisting of 2-30 wt.% V{sub 2}O{sub 5} on a coprecipitated silica-titania support. The formation of nitrous oxide was studied and found to be noticeable when water is not present in the gas and on a catalyst which contains large amounts of crystallites of V{sub 2}O{sub 5}. Chapter 3 deals with international research in the area of deactivation of SCR catalysts in i.e. biofuelled applications. Material from a literature search from December 2001 is presented. It contains general material on the deactivation with alkali metals and SO{sub 2}. Chapter 4 deals with our studies of deactivated SCR catalysts. During 1995-2001 we have studied the deactivation of catalysts in a number of Swedish plants. The sensitivity of zeolites to poisoning in waste combustion (GRAAB) was tested by artificial poisoning with 2 wt.% metal of the elements; Na, K, Mg, Fe, Zn, Cu, Al, Ni and Cr. The combustion of waste at SYSAV gave high contents of Na, Y, Ca, Pb and Zn on the catalyst after 2000 hours on stream. Activity measurements showed that low concentrations of ammonium sulphate, 1-5 vol.%, promotes the SCR reaction. A maximal activity is obtained at around 5 vol.%. There exists an optimal content of ammonium sulphate on the catalyst

Gaseous emissions from a heavy-duty engine equipped with SCR aftertreatment system and fuelled with diesel and biodiesel: Assessment of pollutant dispersion and health risk

Energy Technology Data Exchange (ETDEWEB)

Tadano, Yara S.; Borillo, Guilherme C.; Godoi, Ana Flávia L.; Cichon, Amanda; Silva, Thiago O.B.; Valebona, Fábio B.; Errera, Marcelo R. [Environmental Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil); Penteado Neto, Renato A.; Rempel, Dennis; Martin, Lucas [Institute of Technology for Development, Lactec–Leme Division, 01 LothárioMeissner Ave., Curitiba, PR, 80210-170 (Brazil); Yamamoto, Carlos I. [Chemical Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil); Godoi, Ricardo H.M., E-mail: rhmgodoi@ufpr.br [Environmental Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil)

2014-12-01

The changes in the composition of fuels in combination with selective catalytic reduction (SCR) emission control systems bring new insights into the emission of gaseous and particulate pollutants. The major goal of our study was to quantify NO{sub x}, NO, NO{sub 2}, NH{sub 3} and N{sub 2}O emissions from a four-cylinder diesel engine operated with diesel and a blend of 20% soybean biodiesel. Exhaust fume samples were collected from bench dynamometer tests using a heavy-duty diesel engine equipped with SCR. The target gases were quantified by means of Fourier transform infrared spectrometry (FTIR). The use of biodiesel blend presented lower concentrations in the exhaust fumes than using ultra-low sulfur diesel. NO{sub x} and NO concentrations were 68% to 93% lower in all experiments using SCR, when compared to no exhaust aftertreatment. All fuels increased NH{sub 3} and N{sub 2}O emission due to SCR, a precursor secondary aerosol, and major greenhouse gas, respectively. An AERMOD dispersion model analysis was performed on each compound results for the City of Curitiba, assumed to have a bus fleet equipped with diesel engines and SCR system, in winter and summer seasons. The health risks of the target gases were assessed using the Risk Assessment Information System For 1-h exposure of NH{sub 3}, considering the use of low sulfur diesel in buses equipped with SCR, the results indicated low risk to develop a chronic non-cancer disease. The NO{sub x} and NO emissions were the lowest when SCR was used; however, it yielded the highest NH{sub 3} concentration. The current results have paramount importance, mainly for countries that have not yet adopted the Euro V emission standards like China, India, Australia, or Russia, as well as those already adopting it. These findings are equally important for government agencies to alert the need of improvements in aftertreatment technologies to reduce pollutants emissions. - Highlights: • Emission, dispersion and risk assessment

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.

Design and testing of an independently controlled urea SCR retrofit system for the reduction of NOx emissions from marine diesels.

Science.gov (United States)

Johnson, Derek R; Bedick, Clinton R; Clark, Nigel N; McKain, David L

2009-05-15

Diesel engine emissions for on-road, stationary and marine applications are regulated in the United States via standards set by the Environmental Protection Agency (EPA). A major component of diesel exhaust that is difficult to reduce is nitrogen oxides (NOx). Selective catalytic reduction (SCR) has been in use for many years for stationary applications, including external combustion boilers, and is promising for NOx abatement as a retrofit for mobile applications where diesel compression ignition engines are used. The research presented in this paper is the first phase of a program focused on the reduction of NOx by use of a stand-alone urea injection system, applicable to marine diesel engines typical of work boats (e.g., tugs). Most current urea SCR systems communicate with engine controls to predict NOx emissions based on signals such as torque and engine speed, however many marine engines in use still employ mechanical injection technology and lack electronic communication abilities. The system developed and discussed in this paper controls NOx emissions independentof engine operating parameters and measures NOx and exhaust flow using the following exhaust sensor inputs: absolute pressure, differential pressure, temperature, and NOx concentration. These sensor inputs were integrated into an independent controller and open loop architecture to estimate the necessary amount of urea needed, and the controller uses pulse width modulation (PWM) to power an automotive fuel injector for airless urea delivery. The system was tested in a transient test cell on a 350 hp engine certified at 4 g/bhp-hr of NOx, with a goal of reducing the engine out NOx levels by 50%. NOx reduction capabilities of 41-67% were shown on the non road transient cycle (NRTC) and ICOMIA E5 steady state cycles with system optimization during testing to minimize the dilute ammonia slip to cycle averages of 5-7 ppm. The goal of 50% reduction of NOx can be achieved dependent upon cycle. Further

The Role of Fe2O3 Species in Depressing the Formation of N2O in the Selective Reduction of NO by NH3 over V2O5/TiO2-Based Catalysts

Directory of Open Access Journals (Sweden)

Moon Hyeon Kim

2018-03-01

Full Text Available Promotion of 2.73% Fe2O3 in an in-house-made V2O5-WO3/TiO2 (VWT and a commercial V2O5-WO3/TiO2 (c-VWT has been investigated as a cost effective approach to the suppression of N2O formation in the selective catalytic reduction of NO by NH3 (NH3-SCR. The promoted VWT and c-VWT catalysts all gave a significantly decreased N2O production at temperatures >400 °C compared to the unpromoted samples. However, such a promotion led to the loss in high temperature NO conversion, mainly due to the oxidation of NH3 to N-containing gases, particularly NO. Characterization of the unpromoted and promoted catalysts using X-ray diffraction (XRD, NH3 adsorption-desorption, and Raman spectroscopy techniques could explain the reason why the promotion showed much lower N2O formation levels at high temperatures. The addition of Fe2O3 to c-VWT resulted in redispersion of the V2O5 species, although this was not visible for 2.73% Fe2O3/VWT. The iron oxides exist as a highly-dispersed noncrystalline α-Fe2O3 in the promoted catalysts. These Raman spectra had a new Raman signal that could be tentatively assigned to Fe2O3-induced tetrahedrally coordinated polymeric vanadates and/or surface V-O-Fe species with significant electronic interactions between the both metal oxides. Calculations of the monolayer coverage of each metal oxide and the surface total coverage are reasonably consistent with Raman measurements. The proposed vanadia-based surface polymeric entities may play a key role for the substantial reduction of N2O formed at high temperatures by NH3 species adsorbed strongly on the promoted catalysts. This reaction is a main pathway to greatly suppress the extent of N2O formation in NH3-SCR reaction over the promoted catalysts.

Synthesis of FBD-based PLC design from NuSCR formal specification

International Nuclear Information System (INIS)

Yoo, Junbeom; Cha, Sungdeok; Kim, Chang Hwoi; Song, Duck Yong

2005-01-01

NuSCR is a formal specification language to document requirements for real-time embedded software with nuclear engineering applications in mind. Domain experts actively participated in selecting how to best represent various aspects. It uses tabular notations to specify required computations and automata to document state- or time-dependent behavior. As programmable logic controllers (PLCs) are widely used to implement real-time embedded software, synthesis of PLC code from a formal specification is desirable if transformation rules can be rigorously defined. In addition to improved productivity, results of safety analysis performed on requirements remain valid. In this paper, we demonstrate how NuSCR specification can be translated into semantically equivalent function block diagram (FBD) code. The process, except the initial phase where user provides information on missing or implicit details, is automated. Since executable code can be automatically generated using CASE tools from FBD, much of software development is automated. Proposed technique is currently being used in developing reactor protection system (RPS) for nuclear power plants in Korea, and experience to date has been positive. We demonstrate the proposed approach using the fixed set-point rising trip which is one of the most complex trip logics included in the RPS

Load-Independent Harmonic Mitigation in SCR-Fed Three-Phase Multiple Adjustable Speed Drive Systems with Deliberately Dispatched Firing Angles

DEFF Research Database (Denmark)

Yang, Yongheng; Davari, Pooya; Blaabjerg, Frede

2018-01-01

Adjustable speed drives (ASD) are widely used in industry for energy savings, where low-cost diode rectifiers are still employed as the front-ends, also for simplicity in control and reliability in operation. However, significant harmonics appear at the grid, which should be tackled according...... a harmonic mitigation strategy for multiple ASD systems, where silicon-controlled rectifiers (SCR) with boost converters in the dc-link have been adopted to increase the harmonic-current controllability. More specific, the SCR firing angles are deliberately dispatched among the drive units, which results...

Characterizations of self-combustion reactions (SCR) for the production of nanomaterials used as advanced cathodes in Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Haik, Ortal; Martha, Surendra K.; Sclar, Hadar; Samuk-Fromovich, Zvi; Zinigrad, Ella; Markovsky, Boris [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); Kovacheva, Daniela; Saliyski, Nikolay [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria); Aurbach, Doron, E-mail: aurbach@mail.biu.ac.il [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel)

2009-09-10

In this work, self-combustion reactions (SCR) for the preparation of important cathode materials for rechargeable Li-ion batteries were investigated by thermal analytical tools (DSC, ARC, TGA), electron microscopy, XRD, various spectroscopies (MS, Raman, FTIR) and elemental analysis by ICP. The systems studied include solutions containing metal nitrates at the right stoichiometry and sucrose as a fuel, for the preparation of LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} (layered), LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} (spinel), LiMn{sub 0.33}Ni{sub 0.33}Co{sub 0.33}O{sub 2} (layered), and LiMn{sub 0.4}Ni{sub 0.4}Co{sub 0.2}O{sub 2} (layered). Similar products, which do not depend on the atmosphere of the processes (air or inert) were obtained by spontaneous SCR and the gradual heating of the same solutions by DSC, ARC, and TGA. The reactions involve the partial caramelization of sucrose, complicated by red-ox reactions with the nitrates that form solid products, whose organic part is finally decomposed around 400 {sup o}C. The presence of cobalt ions has a stabilizing effect, which is expressed by the low dissolution rates of Li ions from the solid products thus formed, into aqueous solutions. The reaction mechanisms are discussed herein.

Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

Science.gov (United States)

Zelenay, Piotr; Wu, Gang

2014-04-29

A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

Effect of Co addition on the performance and structure of V/ZrCe catalyst for simultaneous removal of NO and Hg0 in simulated flue gas

Science.gov (United States)

Zhao, Lingkui; Li, Caiting; Du, Xueyu; Zeng, Guangming; Gao, Lei; Zhai, Yunbo; Wang, Teng; Zhang, Junyi

2018-04-01

The effect of CoOx addition on the performance and structure of V2O5/ZrO2-CeO2 catalyst for simultaneous removal of NO and Hg0 in simulated flue gas was investigated by various methods including SEM, BET, XRD, XPS, H2-TPR and FT-IR. It was found that the introduction of CoOx not only greatly enhanced the redox properties of catalysts, but also increased the catalytic performance for simultaneous removal of NO and Hg0. The CoOx-modified V2O5/ZrO2-CeO2 catalyst displayed excellent catalytic activity for NO conversion (89.6%) and Hg0 oxidation (88.9%) at 250 °C under SCR atmosphere. The synergistic effect among vanadium, cobalt, and the ZrCe support could induce oxygen vacancies formation and promote oxygen mobility via charge transfer. Besides, CoOx could assist vanadium species in rapidly changing the valence by the redox cycle of V5+ + Co2+ ↔ V4+ + Co3+. All the above features contribute to the excellent catalytic performance through CoOx addition.

Preparation and Performance of Modified Red Mud-Based Catalysts for Selective Catalytic Reduction of NOx with NH3

Directory of Open Access Journals (Sweden)

Jingkun Wu

2018-01-01

Full Text Available Bayer red mud was selected, and the NH3-SCR activity was tested in a fixed bed in which the typical flue gas atmosphere was simulated. Combined with XRF, XRD, BET, SEM, TG and NH3-Temperature Programmed Desorption (TPD characterization, the denitration characteristics of Ce-doped red mud catalysts were studied on the basis of alkali-removed red mud. The results showed that typical red mud was a feasible material for denitration catalyst. Acid washing and calcining comprised the best treatment process for raw red mud, which reduced the content of alkaline substances, cleared the catalyst pore and optimized the particle morphology with dispersion. In the temperature range of 300–400 °C, the denitrification efficiency of calcined acid washing of red mud catalyst (ARM was more than 70%. The doping of Ce significantly enhanced NH3 adsorption from weak, medium and strong acid sites, reduced the crystallinity of α-Fe2O3 in ARM, optimized the specific surface area and broadened the active temperature window, which increased the NOx conversion rate by an average of nearly 20% points from 250–350 °C. The denitration efficiency of Ce0.3/ARM at 300 °C was as high as 88%. The optimum conditions for the denitration reaction of the Ce0.3/ARM catalyst were controlled as follows: Gas Hourly Space Velocity (GHSV of 30,000 h−1, O2 volume fraction of 3.5–4% and the NH3/NO molar ratio ([NH3/NO] of 1.0. The presence of SO2 in the feed had an irreversible negative effect on the activity of the Ce0.3/ARM catalyst.

Modelling of NO{sub x} emission factors from heavy and light-duty vehicles equipped with advanced aftertreatment systems

Energy Technology Data Exchange (ETDEWEB)

Oliveira, M.L.M., E-mail: monalisa@unifor.br [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Silva, C.M. [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Moreno-Tost, R. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Farias, T.L. [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Jimenez-Lopez, Antonio [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain)

2011-08-15

Highlights: {yields} Alternative SCR materials. {yields} Catalysts used in heavy-duty vehicles are based on V{sub 2}O{sub 5}-WO{sub 3}-TiO{sub 2}. {yields}Zeolites containing transition metal ions as catalysts for urea SCR has increased. {yields} FeZSM5 catalyst can be a possible candidate as far as pollutants regulation is considered. {yields} Regarding N{sub 2}O emissions mordenite based SCR do not emit this pollutant. - Abstract: NO{sub x} emission standards are becoming stringiest over the world especially for heavy-duty vehicles. To comply with current and future regulations some vehicle manufacturers are adopting exhaust aftertreatment systems known as Selective Catalytic Reduction (SCR). The catalysts are based on Vanadium (Va) and the reductant agent based on ammonia. However, Va is listed on the California Proposition 65 List as potentially causing cancer and alternatives are being studied. This paper presents a model based on neural networks that integrated with a road vehicle simulator allows to estimate NO{sub x} emission factors for different powertrain configurations, along different driving conditions, and covering commercial, zeolite and mordenite alternatives as the base monolith for SCR. The research included the experimental study of copper based and iron based zeolites (ZSM5 and Cuban natural mordenite). The response of NO{sub x} conversion efficiency was monitored in a laboratory for varying space velocity, oxygen, sulfur, water, NO{sub x} and SO{sub 2} emulating the conditions of a Diesel engine exhaust along a trip. The experimental data was used for training neural networks and obtaining a mathematical correlation between the outputs and inputs of the SCR system. The developed correlation was integrated with ADVISOR road vehicle simulator to obtain NO{sub x} emission factors and to test each SCR system installed on light-duty and heavy-duty vehicles for standardized driving cycles and real measured driving cycles. Despite having lower NO

Major issues in the design and construction of the stellarator of Costa Rica: SCR-1

International Nuclear Information System (INIS)

Mora, J; Vargas, V I; Villegas, L F; Barillas, L; Monge, J I; Rivas, L

2012-01-01

This paper aims at briefly describing the design and construction issues of the stellarator of Costa Rica 1 (SCR-1). The SCR-1 is a small modular Stellarator for magnetic confinement of plasma developed by the Plasma Physics Group of the Instituto Tecnologico de Costa Rica (ITCR). The SCR-1 is based on the small Spanish Stellarator UST 1 (Ultra Small Torus 1), created by Eng. Vicente Queral. These mains issues consist of the size of the Stellarator, closeness between coils, coupling of ECH to the vacuum chamber and the device for support. The size has become a problem because the vacuum chamber does not allow a lot of space to attach diagnosis devices, the heating system, the vacuum system and the very same support of the chamber. As a result of this lack of space, the Stellarator's coils are placed very close to each other; this means that two of the coils around of the vacuum chamber clash and cannot be placed as designed. The issue regarding the coupling of the ECH (electron cyclotron radio-frequency) to the vacuum chamber comprises the fact that the wave guide with rectangular shape does not match the CF port with circular shape on the vacuum chamber. In addition, the device for supporting the Stellarator has presented a challenge because of its size and the placement of the coils; in other words, there is not enough space between the ports and coils in the Stellarator to place appropriately the device for support.

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

interacting with the ammonium nitrate species on the CuxOy or other copper species on the surface of the zeolite particles, which reduces the ammonium nitrate blocking of the catalyst and thereby results in higher NO2 SCR activity. © 2016 The Author(s).

High-Throughput Screening as a Supplemental Tool for the Development of Advanced Emission Control Catalysts: Methodological Approaches and Data Processing

Directory of Open Access Journals (Sweden)

Andreas Sundermann

2016-01-01

Full Text Available A high-throughput (HT screening platform developed at hte with the application focus on automotive catalysis is described. hte HT units are configured for performing steady-state testing, as well as dynamic tests with fast feed switches, such as lean/rich excursions for the evaluation of NOx storage capacity and efficiency of lean NOx traps (LNT, ammonia storage capacity for selective catalytic reduction (SCR, evaluation of oxygen storage capacity (OSC, as well as lambda sweep tests for screening of three-way catalysts (TWC. Even though catalysts are screened on a rather small scale (~100 mg powder, experience showed that dosing rather complex gas mixtures in concentrations close to that found in real exhaust for the given application is mandatory to generate relevant data. The objective of this work is to give additional insight into HT technology. In the industrial research laboratory, HT screening has matured to become a reliable approach for rapid screening of both reaction parameter spaces, as well as material properties relevant for exhaust gas catalyst development. Due to the speed of optimized screening involving 48 parallel reactors, automated handling of primary data is an imported requirement. Software for data reduction, like estimation of light-off temperature, needs to be robust and handle results for diverse sample libraries in an unattended fashion. In combination with the statistical design of experiment and multivariate data analysis, HT testing has become a valuable enhancement to automotive catalyst development.

ANALYSIS OF SEQUENCE POLYMORPHISM OF SCR CLASS I AND II ALLELES AND STUDY REGULATION OF THEIR EXPRESSION

Directory of Open Access Journals (Sweden)

Jana ŽALUDOVÁ

2012-06-01

Full Text Available Self-incompatibility (AI is a widespread mechanism used by flowering plants to prevent inbreeding depression and helps create and maintain genetic diversity within a species. Oilseed rape (Brassica napus L. and especially its modern varieties are characterized by high level of self-fertility. In an effort to increase the production current breeding is focused on the production of inbred lines for making the F1 hybrids and the self-incompatibility can be an interesting tool for production self- sterile lines. In Brassica napus, we found two recessive alleles of a gene SCR II. Different expression of both alleles does not correspond to phenotypic manifestation of self-incompatibility and we can assume that it is prevailed by repressor gene that does not lie on the S-locus. This is also reason, why the SCR gene cannot serve as a molecular marker of self-incompatibility in Brassica napus, although many authors believe that this gene is essential in AI reaction. Brassica napus belong to plants with complex genetic constitution, is composed by two genomes, A and C, which give the possibility of different interactions and makes it difficult to study compared with diploid B. rapa and B. oleracea. In further study it is therefore important to focus on the interactions between genes SCR, SRK and SLG, and their influence on others, such as supressor gene systems.

Immobilization of molecular catalysts in supported ionic liquid phases.

Science.gov (United States)

Van Doorslaer, Charlie; Wahlen, Joos; Mertens, Pascal; Binnemans, Koen; De Vos, Dirk

2010-09-28

In a supported ionic liquid phase (SILP) catalyst system, an ionic liquid (IL) film is immobilized on a high-surface area porous solid and a homogeneous catalyst is dissolved in this supported IL layer, thereby combining the attractive features of homogeneous catalysts with the benefits of heterogeneous catalysts. In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed. In the first part, general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic liquid and reaction conditions. Secondly, organic reactions in which SILP technology is applied to improve the performance of homogeneous transition-metal catalysts are presented: hydroformylation, metathesis reactions, carbonylation, hydrogenation, hydroamination, coupling reactions and asymmetric reactions.

Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

Directory of Open Access Journals (Sweden)

Ahmed K. Aboul-Gheit

2012-12-01

Full Text Available H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm and the smallest pores (0.4–1.7 nm. The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give Ea and ΔS∗ values compatible with the characterization data of the catalysts.

Energy industry

Science.gov (United States)

Staszak, Katarzyna; Wieszczycka, Karolina

2018-04-01

The potential sources of metals from energy industries are discussed. The discussion is organized based on two main metal-contains wastes from power plants: ashes, slags from combustion process and spent catalysts from selective catalytic NOx reduction process with ammonia, known as SCR. The compositions, methods of metals recovery, based mainly on leaching process, and their further application are presented. Solid coal combustion wastes are sources of various compounds such as silica, alumina, iron oxide, and calcium. In the case of the spent SCR catalysts mainly two metals are considered: vanadium and tungsten - basic components of industrial ones.

Experimental Studies for CPF and SCR Model, Control System, and OBD Development for Engines Using Diesel and Biodiesel Fuels

Energy Technology Data Exchange (ETDEWEB)

Johnson, John; Naber, Jeffrey; Parker, Gordon; Yang, Song-Lin; Stevens, Andrews; Pihl, Josh

2013-04-30

The research carried out on this project developed experimentally validated Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), and Selective Catalytic Reduction (SCR) high‐fidelity models that served as the basis for the reduced order models used for internal state estimation. The high‐fidelity and reduced order/estimator codes were evaluated by the industrial partners with feedback to MTU that improved the codes. Ammonia, particulate matter (PM) mass retained, PM concentration, and NOX sensors were evaluated and used in conjunction with the estimator codes. The data collected from PM experiments were used to develop the PM kinetics using the high‐fidelity DPF code for both NO2 assisted oxidation and thermal oxidation for Ultra Low Sulfur Fuel (ULSF), and B10 and B20 biodiesel fuels. Nine SAE papers were presented and this technology transfer process should provide the basis for industry to improve the OBD and control of urea injection and fuel injection for active regeneration of the PM in the DPF using the computational techniques developed. This knowledge will provide industry the ability to reduce the emissions and fuel consumption from vehicles in the field. Four MS and three PhD Mechanical Engineering students were supported on this project and their thesis research provided them with expertise in experimental, modeling, and controls in aftertreatment systems.

Final Report of a CRADA Between Pacific Northwest National Laboratory and Cummins, Incorporated (CRADA No.PNNL/283): “Enhanced High and Low Temperature Performance of NO_x Reduction Catalyst Materials”

Energy Technology Data Exchange (ETDEWEB)

Gao, Feng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szanyi, Janos [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Yilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Yong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Peden, Charles HF [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Howden, Ken [US Dept. of Energy, Washington, DC (United States); Currier, Neal [Cummins Inc., Columbus, IN (United States); Kamasamudram, Krishna [Cummins Inc., Columbus, IN (United States); Kumar, Ashok [Cummins Inc., Columbus, IN (United States); Li, J. [Cummins Inc., Columbus, IN (United States); Stafford, R. J. [Cummins Inc., Columbus, IN (United States); Yezerets, Aleksey [Cummins Inc., Columbus, IN (United States); Luo, J. [Cummins Inc., Columbus, IN (United States); Chen, H. Y. [Johnson Matthey Company, Royston (United Kingdom)

2016-09-01

The NO_x Storage-Reduction (NSR, also known as lean-NO_x trap – LNT), is based upon the concept of storing NO_x as nitrates over storage components, typically barium species, during a lean-burn operation cycle and then reducing the stored nitrates to N₂ during fuel-rich conditions over a precious metal catalyst [1]. NO_x Selective Catalytic Reduction (SCR), on the other hand, is accomplished by deliberately introducing reductant urea into the engine exhaust to reduce NO_x with the aid of a Cu(Fe)/zeolite catalyst [2]. These two technologies have been recognized as the most promising approaches for meeting stringent NO_x emission standards for diesel vehicles within the Environmental Protection Agency’s (EPA’s) 2007/2010 mandated limits. For NSR, problems arising from either or both thermal and SO₂ deactivation must be addressed to meet durability standards. For SCR, SO₂ deactivation is less of an issue, but hydrothermal deactivation of the zeolite catalysts must be addressed. With continuing R&D efforts in advanced powertrains, highly novel operating modes for internal combustion engines (ICEs) are being researched in order to meet the very stringent new demands for fuel efficiency (e.g., U.S. ‘‘CAFE’’ standards for average miles/gallon are scheduled to increase dramatically over the next 10–15 years). These new ICE engine operation modes, while highly fuel-efficient, result in much lower exhaust temperatures than current engines; temperatures so low that it is hard to imagine how the current catalytic emission control technologies will be able to function. For example, while steady-state operation of the NO_x reduction technology at 150 °C may be required, current ‘‘light-off’’ temperatures for CHA-based zeolite catalysts are closer to 200 °C. Therefore, understanding low-temperature limitations in NO_x reduction has become one

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

KAUST Repository

Li, Hailong; Zhu, Lei; Wu, Shaokang; Liu, Yang; Shih, Kaimin

2016-01-01

.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 Cu

Synthesis of S/Cr doped mesoporous TiO2 with high-active visible light degradation property via solid state reaction route

International Nuclear Information System (INIS)

Liu Shaoyou; Tang Qunli; Feng Qingge

2011-01-01

S/Cr doped mesoporous TiO 2 (S-TiO 2 , Cr-TiO 2 , S-Cr-TiO 2 ) were successfully synthesized via a simple, effective and environmental benign solid state reaction route. The low angle XRD patterns demonstrated that the resulting samples possess mesostructures. The further characterizations via N 2 adsorption-desorption and XPS showed that the typical S/Cr co-doped mesoporous TiO 2 (S-Cr-TiO 2 (5S-5Cr)) possesses mesopore with the high specific surface area of 118.4 m 2 /g and narrow pore size distribution, and both S and Cr have been incorporated into the lattice of TiO 2 with the amounts of 4.16% sulfur and 7.88% chromium, respectively. And Raman spectroscopy shows that the surface of S-Cr-TiO 2 (5S-5Cr) material possesses stretching vibrational peaks at ∼709, ∼793 cm -1 are assignable to the Ti-O-Cr, O-Cr (Ti)-OH bonds, respectively. Interestingly, the UV-vis displayed that the absorption regions of S/Cr doped mesoporous TiO 2 cover the visible light region. As for the series of S-Cr-TiO 2 samples, the absorption region even extends to near infrared region with strong adsorption. Moreover, compared with the pure titanium dioxide (P25-TiO 2 ), the photodegradation properties of bromocresol green (BCG) on the S/Cr doped mesoporous TiO 2 showed excellent photocatalytic properties under visible light irradiation. Within 50 min visible light irradiation, 82.6% of the initial BCG was degraded for the S-Cr-TiO 2 (6S-4Cr) photocatalyst.

Supported Metal Zeolites as Environmental Catalysts for Reduction of NOx Molecules

International Nuclear Information System (INIS)

May Nwe Win; Tin Tin Aye; Kyaw Myo Naing; Nyunt Wynn; Maung Maung Htay

2005-09-01

The NOx contamination of air is a major pollutant due to its reaction with the volatile organic compounds, which give rise to ground level (tropospheric) ozone. It is a conventional fact that NOx are one of the major components of car exhaust. In view of that fact, to sustain the tropospheric ozone is to reduce the amount of NOx in the air. Therefore, this paper is concerned with the catalytic activity of Fe-loaded zeolite and Cu-loaded zeolite used to decompose NIOx by SCR (selective catalytic reduction) reaction with very high activity have been studied. Their preparations, characterization by XRD, FT-IR and SEM were also studied. Fe and Cu containig were prepared by soild state ion-exchange method under ambient presure and at the temperature of 600C for 4 hours. From this study, selective catalytic reduction rection was observed, showing about 87% conversion of the NOx molecule with the corresponding optimum amount of catalyst (1.0+-0.5)g working under the reactor space volume of 30cm3 at ambient temperature (30-32)C

Oxidation catalyst

Science.gov (United States)

Ceyer, Sylvia T.; Lahr, David L.

2010-11-09

The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

JV Task 126 - Mercury Control Technologies for Electric Utilities Burning Bituminous Coal

Energy Technology Data Exchange (ETDEWEB)

Jason Laumb; John Kay; Michael Jones; Brandon Pavlish; Nicholas Lentz; Donald McCollor; Kevin Galbreath

2009-03-29

The EERC developed an applied research consortium project to test cost-effective mercury (Hg) control technologies for utilities burning bituminous coals. The project goal was to test innovative Hg control technologies that have the potential to reduce Hg emissions from bituminous coal-fired power plants by {ge}90% at costs of one-half to three-quarters of current estimates for activated carbon injection (ACI). Hg control technology evaluations were performed using the EERC's combustion test facility (CTF). The CTF was fired on pulverized bituminous coals at 550,000 Btu/hr (580 MJ/hr). The CTF was configured with the following air pollution control devices (APCDs): selective catalytic reduction (SCR) unit, electrostatic precipitator (ESP), and wet flue gas desulfurization system (WFDS). The Hg control technologies investigated as part of this project included ACI (three Norit Americas, Inc., and eleven Envergex sorbents), elemental mercury (Hg{sup 0}) oxidation catalysts (i.e., the noble metals in Hitachi Zosen, Cormetech, and Hitachi SCR catalysts), sorbent enhancement additives (SEAs) (a proprietary EERC additive, trona, and limestone), and blending with a Powder River Basin (PRB) subbituminous coal. These Hg control technologies were evaluated separately, and many were also tested in combination.

A proposal to pulse the Bevatron/Bevalac main guide field magnet with SCR power supplies

International Nuclear Information System (INIS)

Frias, B.; Alonso, J.; Dwinell, R.; Lothrop, F.

1989-01-01

The Bevatron/Bevalac Main Guide Field Power Supply was originally designed to provide a 15,250 Volt DC. at sign 8400 Ampere peak magnet pulse. Protons were accelerated to 6.2 Gev. The 128 Megawatt (MW) pulse required two large motor-generator (MG) sets with 67 ton flywheels to store 680 Megajoules of energy. Ignitron rectifiers are used to rectify the generator outputs. Acceleration of heavy ions results in an operating schedule with a broad range of peak fields. The maximum field of 12.5 kilogauss requires a peak pulse of 80 MW. Acceleration of ions to 1.0 kilogauss requires an 8 MW peak pulse. One MG set can provide pulses below 45 MW. Peak pulses of less than 15 MW are now a large block of the operating schedule. A proposal has been made to replace the existing MG system with eight SCR power supplies for low field operation. The SCR supplies will be powered directly from the Lawrence Berkeley Laboratory's 12.3 KV. power distribution system. This paper describes the many advantages of the plan. 4 refs., 3 figs., 3 tabs

Part 1: characterization of beam synthesized catalytic materials. Part 2: further development of molecular SIMS

International Nuclear Information System (INIS)

Scheifers, S.M.

1985-01-01

Part I of this thesis concerns characterization of catalyst materials prepared by an ion beam implanter and by a multiple expansion cluster source. Ion beam synthesis was carried out on a 250-kev ion implanter. After assembling a special reaction chamber, zeolites were implanted with phosphorous and iron. This work contributed to development of a sputter reactor for ion beam synthesis. Silver catalysts were examined in a reactor designed, built and evaluated for catalysts produced by the sputter reactor and by a multiple expansion cluster source. Small surface area silver foil catalysts and silver cluster catalysts showed kinetic activity for epoxidation of ethylene. Positive results for the small surface area silver cluster catalyst demonstrate the feasibility of studying these catalysts with the special reactor. Part 2 concerns fundamentals and applications of secondary ion mass spectrometry. A data system was implemented for a secondary ion mass spectrometer that involved design and construction of a computer interface. Software routines for the interface were written in assembly language for increased operation efficiency

Quick Guide to Flash Catalyst

CERN Document Server

Elmansy, Rafiq

2011-01-01

How do you transform user interface designs created in Photoshop or Illustrator into interactive web pages? It's easier than you think. This guide shows you how to use Adobe Flash Catalyst to create interactive UIs and website wireframes for Rich Internet Applications-without writing a single line of code. Ideal for web designers, this book introduces Flash Catalyst basics with detailed step-by-step instructions and screenshots that illustrate every part of the process. You'll learn hands-on how to turn your static design or artwork into working user interfaces that can be implemented in Fla

Arabidopsis SHR and SCR transcription factors and AUX1 auxin influx carrier control the switch between adventitious rooting and xylogenesis in planta and in in vitro cultured thin cell layers.

Science.gov (United States)

Della Rovere, F; Fattorini, L; D'Angeli, S; Veloccia, A; Del Duca, S; Cai, G; Falasca, G; Altamura, M M

2015-03-01

Adventitious roots (ARs) are essential for vegetative propagation. The Arabidopsis thaliana transcription factors SHORT ROOT (SHR) and SCARECROW (SCR) affect primary/lateral root development, but their involvement in AR formation is uncertain. LAX3 and AUX1 auxin influx carriers contribute to primary/lateral root development. LAX3 expression is regulated by SHR, and LAX3 contributes to AR tip auxin maximum. In contrast, AUX1 involvement in AR development is unknown. Xylogenesis is induced by auxin plus cytokinin as is AR formation, but the genes involved are largely unknown. Stem thin cell layers (TCLs) form ARs and undergo xylogenesis under the same auxin plus cytokinin input. The aim of this research was to investigate SHR, SCR, AUX1 and LAX3 involvement in AR formation and xylogenesis in intact hypocotyls and stem TCLs in arabidopsis. Hypocotyls of scr-1, shr-1, lax3, aux1-21 and lax3/aux1-21 Arabidopsis thaliana null mutant seedlings grown with or without auxin plus cytokinin were examined histologically, as were stem TCLs cultured with auxin plus cytokinin. SCR and AUX1 expression was monitored using pSCR::GFP and AUX1::GUS lines, and LAX3 expression and auxin localization during xylogenesis were monitored by using LAX3::GUS and DR5::GUS lines. AR formation was inhibited in all mutants, except lax3. SCR was expressed in pericycle anticlinally derived AR-forming cells of intact hypocotyls, and in cell clumps forming AR meristemoids of TCLs. The apex was anomalous in shr and scr ARs. In all mutant hypocotyls, the pericycle divided periclinally to produce xylogenesis. Xylary element maturation was favoured by auxin plus cytokinin in shr and aux1-21. Xylogenesis was enhanced in TCLs, and in aux1-21 and shr in particular. AUX1 was expressed before LAX3, i.e. in the early derivatives leading to either ARs or xylogenesis. AR formation and xylogenesis are developmental programmes that are inversely related, but they involve fine-tuning by the same proteins, namely SHR

Alternative alkali resistant deNO{sub x} technologies

Energy Technology Data Exchange (ETDEWEB)

Buus Kristensen, S.; Due-Hansen, J.; Putluru, S.S.R.; Kunov-Kruse, A.; Fehrmann, R.; Degn Jensen, A.

2011-04-15

The aim of the project is to identify, make and test possible alkali resistant deNO{sub x} catalysts for use in biomass, waste or fossil fuelled power plants, where the flue gas typically has a high level of potassium compounds, which rapidly de-activate the traditional V{sub 2}O{sub 5}/TiO{sub 2} catalyst. Furthermore, new technologies are investigated based on a protective coating of the catalyst elements and selective reversible absorption of NO{sub x} with ionic liquids. Several promising alternative deNO{sub x} catalyst types have been made during the project: 1) V, Fe, CU based nano-TiO{sub 2} and nano-TiO{sub 2}-SO{sub 4}{sup 2-} catalysts; 2) V/ZrO{sub 2}-SO{sub 2}- and V/ZrO{sub 2}-CeO{sub 2} catalysts; V, Fe, Cu based Zeolite catalysts; 4) V, Fe, Cu based Heteropoly acid catalysts. Several of these are promising alternatives to the state-of the art industrial reference catalyst. All catalysts prepared in the present project exhibit higher to much higher alkali resistance compared to the commercial reference. Furthermore, two catalysts, i.e. 20 wt% V{sub 2}O-3-TiO{sub 2} nano-catalyst and the 4 wt% CuO-Mordenite zeolite based catalyst have also a higher initial SCR activity compared to the commercial one before alkali poisoning. Thus, those two catalysts might be attractive for SCR deNO{sub x} purposes even under ''normal'' fuel conditions in power plants and elsewhere making them strong candidates for further development. These efforts regarding all the promising catalysts will be pursued after this project has expired through a one year Proof of Concept project granted by the Danish Agency for Science, Technology and Innovation. Also the severe rate of deactivation due to alkali poisons can be avoided by coating the vanadium catalyst with Mg. Overall, the protective coating of SCR catalysts developed in the project seems promising and a patent application has been filed for this technology. Finally, a completely different approach to

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.

A series of NiMo/Al{sub 2}O{sub 3} catalysts containing boron and phosphorus. Part 2. Hydrodenitrogenation and hydrodesulfurization using heavy gas oil derived from Athabasca bitumen

Energy Technology Data Exchange (ETDEWEB)

Ferdous, D.; Dalai, A.K. [Catalysis and Chemical Reactor Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, Saskatoon (Canada) SK S7N 5C9; Adjaye, J. [Syncrude Canada Ltd., Edmonton Research Center (Canada)

2004-04-08

The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) activity of a series of NiMo/Al{sub 2}O{sub 3} catalyst containing boron (B) and phosphorus (P) were tested in a trickle bed reactor using heavy gas oil derived from Athabasca bitumen. Detailed characterization of these catalysts is given in Part I of this paper. Addition of B and P caused the formation of extremely strong acid sites on the catalyst and enhanced its HDN activity. The total (TN), basic (BN) and non-basic nitrogen (NBN) conversions increased from 61.9 to 78.0wt.%, from 78.9 to 93.0wt.% and from 52.8 to 70.0wt.%, respectively, with the increase in B concentration from 0 to 1.7wt.% to NiMo/Al{sub 2}O{sub 3} catalyst. Similarly, TN, BN and NBN conversions increased from 61.9 to 78.4wt.%, from 78.9 to 91.0wt.%, and from 52.8 to 71.6wt.% with the addition of 2.7wt.% P. Though the addition of B and P to NiMo/Al{sub 2}O{sub 3} catalyst did not show any significant effect on S conversion, the HDN and HDS activities of the catalyst containing 1.7wt.% B and the one containing 2.7wt.% P are comparable to those of a commercial catalyst. The activity over extended period indicated that catalysts L and K were more stable (lower deactivation rate) in terms of nitrogen removal activity than catalyst B (reference catalyst). On the other hand, the stability for sulfur removal was comparable with catalyst B. Selected catalysts after use were characterized using BET surface area, TPR, TPD and SEM techniques which were correlated further with their activities.

Mitigation of PAH and nitro-PAH emissions from nonroad diesel engines.

Science.gov (United States)

Liu, Z Gerald; Wall, John C; Ottinger, Nathan A; McGuffin, Dana

2015-03-17

More stringent emission requirements for nonroad diesel engines introduced with U.S. Tier 4 Final and Euro Stage IV and V regulations have spurred the development of exhaust aftertreatment technologies. In this study, several aftertreatment configurations consisting of diesel oxidation catalysts (DOC), diesel particulate filters (DPF), Cu zeolite-, and vanadium-based selective catalytic reduction (SCR) catalysts, and ammonia oxidation (AMOX) catalysts are evaluated using both Nonroad Transient (NRTC) and Steady (8-mode NRSC) Cycles in order to understand both component and system-level effects of diesel aftertreatment on emissions of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nitro-PAH). Emissions are reported for four configurations including engine-out, DOC+CuZ-SCR+AMOX, V-SCR+AMOX, and DOC+DPF+CuZ-SCR+AMOX. Mechanisms responsible for the reduction, and, in some cases, the formation of PAH and nitro-PAH compounds are discussed in detail, and suggestions are provided to minimize the formation of nitro-PAH compounds through aftertreatment design optimizations. Potency equivalency factors (PEFs) developed by the California Environmental Protection Agency are then applied to determine the impact of aftertreatment on PAH-derived exhaust toxicity. Finally, a comprehensive set of exhaust emissions including criteria pollutants, NO2, total hydrocarbons (THC), n-alkanes, branched alkanes, saturated cycloalkanes, aromatics, aldehydes, hopanes and steranes, and metals is provided, and the overall efficacy of the aftertreatment configurations is described. This detailed summary of emissions from a current nonroad diesel engine equipped with advanced aftertreatment can be used to more accurately model the impact of anthropogenic emissions on the atmosphere.

On-line alkali monitoring - Part 1

International Nuclear Information System (INIS)

Andersson, Christer; Ljung, P.; Woxlin, H.

1997-02-01

As a consequence of the increased knowledge of the environmental impact of combustion based heat and power generation, the use of renewable biofuels will be increased. An obstacle associated to biofuel combustion compared to other fuels is the large release of alkali. Alkali compounds in flue gases are known to cause severe operational problems. Three of the major problems are; fouling of superheating tubes (causing reduced heat transfer and possibly corrosion), agglomeration of the bed material in fluidized beds, and poisoning of SCR catalysts. Yet another alkali related problem arises when, in order to increase the electric efficiency of combustion power plants, combined-cycle technology is used. Alkali vapour present in the fuel gas for the gas turbine is condensed to particles which increase corrosion and erosion of the turbine blades. The research on ash related operational problems has to be extended in order to ensure future use of biofuels in heat and power generation. In all successful research, adequate tools are necessary. To investigate ash related problems the key issue is to be able to perform continuous alkali measurements. This pilot study has investigated the need of continuous alkali measurements, which alkali species are harmful in the different applications and also available instrumentation capable of measuring the specific alkali species. The report gives a short summary presenting alkali related operational problems. In addition a schematic overview is given, showing the alkali species that possibly can exist in various parts of the power plant. 48 refs, 13 figs, 4 tabs

Petroleum residue upgrading with dispersed catalysts: Part 2. Effect of operating conditions

Energy Technology Data Exchange (ETDEWEB)

Panariti, N.; Del Bianco, A.; Del Piero, G. [ENITECNOLOGIE S.p.A, Via Maritano 26, 20097 San Donato Mil (Italy); Marchionna, M. [SNAMPROGETTI S.p.A, Via Maritano 26, 20097 San Donato Mil (Italy); Carniti, P. [Universita degli Studi di Milano, Dip. Chimica Fisica ed Elettrochimica, Via Celoria 20, Milan (Italy)

2000-12-04

The hydrotreatment of a petroleum residue in the presence of dispersed molybdenite was carried out within a wide range of operating conditions and catalyst loading. The effect of reaction severity as well as of molybdenum concentration on product distribution and quality was studied. Based on the experimental results, a simplified reaction scheme was proposed. The hydroprocessing of the residue was described in terms of the competition between two reactions: the direct conversion of the feedstock to distillate and coke, and the catalytic hydrogenation. Compared to thermal conditions, the presence of dispersed molybdenite controls very well coke formation; however, a trend of increasing formation of solids was observed at high catalyst concentrations. The overall upgrading of the feedstock requires significant amounts of molybdenum as well as relatively high hydrogen pressure.

Studies on recycling and utilization of spent catalysts. Preparation of active hydrodemetallization catalyst compositions from spent residue hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Marafi, Meena; Stanislaus, Antony [Petroleum Refining Department, Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat (Kuwait)

2007-02-15

Spent catalysts form a major source of solid wastes in the petroleum refining industries. Due to environmental concerns, increasing emphasis has been placed on the development of recycling processes for the waste catalyst materials as much as possible. In the present study the potential reuse of spent catalysts in the preparation of active new catalysts for residual oil hydrotreating was examined. A series of catalysts were prepared by mixing and extruding spent residue hydroprocessing catalysts that contained C, V, Mo, Ni and Al{sub 2}O{sub 3} with boehmite in different proportions. All prepared catalysts were characterized by chemical analysis and by surface area, pore volume, pore size and crushing strength measurements. The hydrodesulfurization (HDS) and hydrodemetallization (HDM) activities of the catalysts were evaluated by testing in a high pressure fixed-bed microreactor unit using Kuwait atmospheric residue as feed. A commercial HDM catalyst was also tested under similar operating conditions and their HDS and HDM activities were compared with that of the prepared catalysts. The results revealed that catalyst prepared with addition of up to 40 wt% spent catalyst to boehmite had fairly high surface area and pore volume together with large pores. The catalyst prepared by mixing and extruding about 40 wt% spent catalyst with boehmite was relatively more active for promoting HDM and HDS reactions than a reference commercial HDM catalyst. The formation of some kind of new active sites from the metals (V, Mo and Ni) present in the spent catalyst is suggested to be responsible for the high HDM activity of the prepared catalyst. (author)

Catalysts, methods of making catalysts, and methods of use

KAUST Repository

Renard, Laetitia; El Eter, Mohamad; Caps, Valerie; Basset, Jean-Marie

2014-01-01

Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

Catalysts, methods of making catalysts, and methods of use

KAUST Repository

Renard, Laetitia

2014-03-06

Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

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.

Moessbauer spectroscopic investigations of Fe/Mn-Fischer-Tropsch-catalysts

International Nuclear Information System (INIS)

Deppe, P.; Papp, H.; Rosenberg, M.

1986-01-01

The phase composition of Fe/Mn oxide catalysts of different compositions after 200 h of Fischer-Tropsch synthesis have been investigated by Moessbauer spectroscopy at room temperature, 77 K and 5 K. The final composition of the bulk catalysts depends strongly on the Mn content and the temperature of reduction before the synthesis. Catalytic activity and selectivity are partly correlated to this phase composition. (Auth.)

Self-regenerative function of the intelligent automotive catalyst

International Nuclear Information System (INIS)

Tanaka, Hirohisa; Nishihata, Yasuo

2007-01-01

Intelligent catalyst, in which noble metals are used as an active part of automotive catalyst, has been considered for keeping up their sufficient activity. The noble metals have a function of cleaning up the exhaust gas as well as that of self-regeneration. In 2002, a Pd system has been put to practical use, and continuously Rh and Pt systems have been commercialized. Now the catalyst has been used in more than three million vehicles. In this report, the atomic level mechanism of the catalyst and its self-regeneration function getting from analyses using synchrotron radiation are introduced. By the analysis using the Spring-8, the mechanism of keeping the active state of the Pd Perovskite Oxide without degradation was identified. The DXAFS (Dispersive X-ray Absorption Fine Structure) analysis in the ESRF (European Synchrotron Radiation Facility) made clear the self-regeneration mechanism of the Pd Perovskite Oxide. This knowledge could lead to the practical development of the Rh and Pt systems. The catalyst technology is counted on balancing resources of the noble metal and environmental sustainability. (A.H.)

Basic study of catalyst aging in the H-coal process

Energy Technology Data Exchange (ETDEWEB)

Cable, T.L.; Massoth, F.E.; Thomas, M.G.

1985-04-01

Samples of CoMo/Al/sub 2/O/sub 3/ catalysts used in an H-coal process demonstration run were studied to determine causes of catalyst deactivation. Physical and surface properties of the aged and regenerated catalysts were examined. Model compounds were used to assess four catalyst activity functions, viz., hydrodesulfurization (HDS), hydrogenation, cracking and hydrodeoxygenation (HDO). Other tests were performed to study the effects of coke and metals separately on the four catalyst activity functions. Catalyst coke content and metal deposits first increased rapidly, then more gradually with exposure time in the process run. Surface area and pore volume markedly decreased with exposure time. Catalyst activities of aged catalysts showed a rapid decline with exposure time. One-day exposure to coal resulted in significant losses in HDS and hydrogenation activities and nearly complete loss in cracking and HDO activities. Although metal deposits caused some permanent catalyst deactivation, coke had a much greater effect. Regenerated catalysts showed less recovery of catalytic activity as processing time increased. These results agreed well with product inspections from the process run. Oxygen chemisorption on aged-regenerated catalysts decreased with catalyst exposure time, indicating a significant loss of active sites. However, ESCA results showed no evidence of extensive sintering of the active MoS/sub 2/ phase. Permanent deactivation of the longer-time exposed catalysts can be ascribed, at least partly, to lateral growth of the active molybdenum sulfide phase. In addition, some loss in cobalt promotion occurred early in the process, which may account for the rapid loss in HDS and HDO activity in regenerated catalysts. 24 references.

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, Franç ois; Couble, Julien; Geantet, Christophe; Guilhaume, Nolven; Puzenat, Eric; Gros, Sé bastien; Porcheron, Lynda; Kanniche, Mohamed; Bianchi, Daniel

2015-01-01

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, François

2015-07-16

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

Harmonic Distortion Performance of Multi Three-Phase SCR-Fed Drive Systems with Controlled DC-Link Current under Unbalanced Grid

DEFF Research Database (Denmark)

Soltani, Hamid; Davari, Pooya; Blaabjerg, Frede

2017-01-01

. In this paper, the main aim is to analyze the effects of the grid unbalanced voltage on the multi-unit three-phase ASDs with the Silicon-Controlled Rectifier (SCR)-fed front-end rectifiers, where the DC-link current is controlled utilizing an Electronic Inductor (EI) technique. In this respect, the main...

Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

Directory of Open Access Journals (Sweden)

Qinghe Zheng

2015-10-01

Full Text Available The rhodium (Rh component in automotive three way catalysts (TWC experiences severe thermal deactivation during fuel shutoff, an engine mode (e.g., at downhill coasting used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by reduction with H2 generated through steam reforming catalyzed by Rh0 sites. The present work reports the effects of the two processes on the activity and properties of 0.5% Rh/Al2O3 and 0.5% Rh/CexOy-ZrO2 (CZO as model catalysts for Rh-TWC. A very brief introduction of three way catalysts and system considerations is also given. During simulated fuel shutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al2O3. Catalyst characterization techniques including BET surface area, CO chemisorption, TPR, and XPS measurements were applied to examine the roles of metal-support interactions in each catalyst system. For Rh/Al2O3, strong metal-support interactions with the formation of stable rhodium aluminate (Rh(AlO2y complex dominates in fuel shutoff, leading to more difficult catalyst regeneration. For Rh/CZO, Rh sites were partially oxidized to Rh2O3 and were relatively easy to be reduced to active Rh0 during regeneration.

Design and implementation of mixing chambers to improve thermal decomposition of urea for NOX abatement

KAUST Repository

Lee, Junggil

2012-10-01

Urea-selective catalytic reduction (SCR) has been reported as the most promising technique for adherence to NOX emissions regulations. In the urea-SCR process, NH3 is generated by urea thermal decomposition and hydrolysis and is then used as a reductant of NOX in the SCR catalyst. Therefore, improving the NOX conversion efficiency of urea-SCR requires enhancement of thermal decomposition upstream of the SCR catalyst. In the present work, two types of mixing chambers were designed and fabricated to improve urea thermal decomposition, and experiments with and without a mixing chamber were carried out to analyze thermal-decomposition characteristics of urea in the exhaust pipe with respect to inlet velocity (4-12μm/s) and temperature (350°C-500°C). Urea thermal decomposition is greatly enhanced at higher gas temperatures. At an inlet velocity of 6μm/s in the A-type mixing chamber, NH3 concentrations generated along the exhaust pipe were about 171% and 157% greater than those without the mixing chamber for inlet temperatures of 400°C and 500°C, respectively. In the case of the B-type mixing chamber, NH3 concentrations generated at inlet temperatures of 400°C and 500°C were about 147% and 179% greater than those without the mixing chamber, respectively. Note that the implementation of mixing chambers significantly enhanced conversion of urea to NH3 because it increased the residence time of urea in the exhaust pipe and improved mixing between urea and exhaust gas. © 2012, Mary Ann Liebert, Inc.

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al2O3

DEFF Research Database (Denmark)

Tamm, Stefanie; Olsson, Louise; Fogel, Sebastian

2013-01-01

A global kinetic model which describes H2-assisted NH3-SCR over an Ag/Al2O3 monolith catalyst has been developed. The intention is that the model can be applied for dosing NH3 and H2 to an Ag/Al2O3 catalyst in a real automotive application as well as contribute to an increased understanding of th...

An introduction to catalyst

International Nuclear Information System (INIS)

Jeon, Hak Je

1988-11-01

This book explains basic conception of catalyst such as definition, velocity of chemical reaction and velocity of catalyst reaction, absorption with absorption energy and chemical absorption, pore structure with the role of pore and measurement of pore structure, catalyst activity on solid structure, electrical property on catalyst activity, choice and design of catalyst, catalytic reaction with reaction velocity and chemical equilibrium and reaction velocity model, measurement of reaction velocity and material analysis, catalyst for mixed compound, catalyst for solid acid and catalyst for supported metal.

Characterisation and activation of catalysts for recombination of radiolysis gas

International Nuclear Information System (INIS)

Bolz, Michael; Koehler, Jan; Schorle, Rolf; Helf, Achim

2011-01-01

Radiolysis gas is produced by radiolysis of cooling water during the operation of boiling water reactors. Small amounts of radiolysis gas can accumulate at dead ends of pipes in the water-steam circuit. Under certain conditions, it can accumulate even to higher concentrations. To avoid these accumulations, small catalysts are built in. As part of a diploma thesis, the catalysts were analysed and characterised. (orig.)

Chemical changes in non-reduced catalysts used for ammonia synthesis

International Nuclear Information System (INIS)

Peev, T.M.; Kyrova, Z.; Bojinova, A.I.

1980-01-01

Samples of non-reduced industrial catalysts CA-1 for ammonia synthesis were studied by using Moessbauer spectroscopy. The conditions of the normal storing of this catalyst were changed. After 6 months it was found that under the influence of moisture and air oxygen a considerable part of the magnetite was converted to α-Fe 2 O 3 , α-FeOOH and γ-FeOOH. (author)

Further studies on hydration of alkynes by the PtCl4-CO catalyst

Energy Technology Data Exchange (ETDEWEB)

Israelsohn, Osnat; Vollhardt, K. Peter C.; Blum, Jochanan

2002-01-18

Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl{sub 4}-CO catalyzed hydration is suggested on the basis of the present study.

Design and preliminary results for a fast bipolar resonant discharge pulser using SCR switches for driving the injection bump magnets at the ALS

International Nuclear Information System (INIS)

Stover, G.; Reginato, L.

1993-05-01

A fast (4.0 us half period) resonant discharge pulser using SCRs has been designed and constructed to drive the injection bump magnet system at the Advanced Light Source (ALS). The pulser employs a series-parallel arrangement of Silicon Controlled Rectifiers (SCRS) that creates a bipolar high voltage (±10 KV), high peak current (6600 amps.) and a high di/dt (6000 amp/us) switch network that discharges a capacitor bank into the magnet load. Fast recovery diodes in series with the SCRs significantly reduces the SCR turn-off time during the negative current cycle of the magnet. The SCR switch provides a very reliable and stable alternative to the gas filled Thyratron. A very low impedance transmission system allows the pulser system to reside completely outside the storage ring shielding wall

Perturbed angular correlation study of the ion exchange of indium into silicalite zeolites

International Nuclear Information System (INIS)

Ramallo-Lopez, J.M.; Requejo, F.G.; Renteria, M.; Bibiloni, A.G.; Miro, E.E.

1999-01-01

Two indium-containing silicalite zeolites (In/H-ZSM5) catalysts prepared by wet impregnation and ionic exchange were characterized by the Perturbed Angular Correlation (PAC) technique using 111 In as probe to determine the nature of the indium species. Some of these species take part in the catalytic reaction of the selective reduction (SCR) of NO x with methane. PAC experiments were performed at 500 deg. C in air before and after reduction-reoxidation treatments on the catalysts in order to determine the origin of the different hyperfine interactions and then the degree of ionic exchange. Complementary catalytic activity characterizations were also performed.PAC experiments performed on the catalyst obtained by wet impregnation showed that all In-atoms form In 2 O 3 crystallites while almost 70% of In-atoms form In 2 O 3 in the catalyst obtained by ionic exchange. The PAC experiments of both catalysts performed after the reduction-reoxidation treatment revealed the presence of two hyperfine interactions, different from those corresponding to indium in In 2 O 3 . These hyperfine interactions should be associated to disperse In species responsible of the catalytic activity located in the ionic exchange-sites of the zeolites

Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

Directory of Open Access Journals (Sweden)

Ernő E. Kiss

2012-12-01

Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

Graphene-supported platinum catalysts for fuel cells

DEFF Research Database (Denmark)

Seselj, Nedjeljko; Engelbrekt, Christian; Zhang, Jingdong

2015-01-01

Increasing concerns with non-renewable energy sources drive research and development of sustainable energy technology. Fuel cells have become a central part in solving challenges associated with energy conversion. This review summarizes recent development of catalysts used for fuel cells over the...

Regeneration and sulfur poisoning behavior of In/H-BEA catalyst for NO{sub x} reduction by CH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Pan, Hua; Jian, Yanfei; Yu, Yanke, E-mail: yankeyu@xjtu.edu.cn; He, Chi, E-mail: chi_he@xjtu.edu.cn; Shen, Zhenxing; Liu, Hongxia

2017-04-15

Highlights: • Sulfur poisoning mechanism of In/H-BEA was investigated for CH{sub 4}-SCR by in situ DRIFT. • H{sub 2} reduction could reduce In{sub 2}(SO{sub 4}){sub 3} to InO{sup +} via In{sub 2}(SO{sub 4}){sub 3} → In{sub 2}O{sub 3} → In(OH){sub 2}{sup +} → InO{sup +}. • The optimal regeneration parameters of H{sub 2} reduction was 400 °C and 60 min. - Abstract: Sulfur poisoning and regeneration behavior of In/H-BEA catalyst were carried out in NO{sub x} reduction by CH{sub 4}. In/H-BEA catalyst exhibited a poor resistance to sulfur dioxide after addition of 200 ppm SO{sub 2} and 10 vol.% H{sub 2}O into NO reduction with CH{sub 4} at 450 °C for 45 h. Sulfur poisoning of In/H-BEA was attributed to the inhibition of NO{sub x} adsorption on Brønsted acid sites, suppression of reaction intermediates generation on the active sites, and the formation of surface sulfate species. The formation of surface sulfate reduced the availability of surface active sites, blocked the pore structure and decreased the surface area of catalyst. These changes in chemical and textural properties resulted in a severe loss in the activity of sulfated In/H-BEA catalyst for NO reduction with CH{sub 4}. H{sub 2} reduction is a promising technology for regeneration of In/H-BEA deactivated by SO{sub 2} for removing NO{sub x} from lean-burn and diesel exhausts. Indium sulfate could be reduced by H{sub 2} to InO{sup +} with In{sub 2}O{sub 3} and In(OH){sub 2}{sup +} as the intermediates. The optimal parameters of H{sub 2} reduction was regeneration temperature of 400 °C and regeneration time of 60 min which completely recovered the catalytic activity of In/H-BEA.

Engelhard and IFP/Procatalyse set up worldwide catalysts venture

International Nuclear Information System (INIS)

Hunter, D.

1992-01-01

The new joint venture between Engelhard (Iselin, N) and Procatalyse (Paris), jointly owned by process licenser Institut Francais de Petrole (IFP; Rueil Malmaison, France) and Rhone-Poulenc (RP; Paris), marks the latest episode in the worldwide catalyst industry's restructuring. The operation will combine Engelhard's catalyst line, apart from its fluid catalytic cracking (FCC) and emission catalysts, with Procatalyse's offering. To be launched at the beginning of 1993, the venture will have annual sales of about $75 million. Reforming catalysts will be the biggest part of the venture's lineup at the outset, making it number three in the US, behind UOP - which dominates the sector - and Criterion. IFP is starting to establish a presence in North America with its reforming technology. But flat gasoline demand and reductions on aromatics in gasoline limit requirements for new reforming units, comments one competitor. Although lower sulfur specifications are putting some new demand into the hydrodesulfurization (HDS) catalyst market, both partners play down their prospects. The sector, whose leaders are Akzo and Crtierion, is continuing to suffer from severe overcapacity. Procatalyse's HDS business is mainly linked to IFP licensees, while Engelhard is due to mothball its Salt Lake City HDS catalyst plant by year-end, transferring output to Elyria

Catalyst support structure, catalyst including the structure, reactor including a catalyst, and methods of forming same

Science.gov (United States)

Van Norman, Staci A.; Aston, Victoria J.; Weimer, Alan W.

2017-05-09

Structures, catalysts, and reactors suitable for use for a variety of applications, including gas-to-liquid and coal-to-liquid processes and methods of forming the structures, catalysts, and reactors are disclosed. The catalyst material can be deposited onto an inner wall of a microtubular reactor and/or onto porous tungsten support structures using atomic layer deposition techniques.

Recent Advances in the Mechanistic Studies of Alkylaromatic Conversions over Zeolite Catalysts

International Nuclear Information System (INIS)

Min, Hyung-Ki; Hong, Suk Bong

2013-01-01

The transformation of alkylaromatic hydrocarbons using zeolite catalysts play big part in the current petrochemical industry. Here we review recent advances in the understanding of the reaction mechanisms of various alkylaromatic conversions with respect to the structural and physicochemical properties of zeolite catalysts employed. Indeed, the shape-selective nature of zeolite catalysts determines the type of reaction intermediates and hence the prevailing reaction mechanism together with the product distribution. The prospect of zeolite catalysis in the development of more efficient petrochemical processes is also described

Life Support Catalyst Regeneration Using Ionic Liquids and In Situ Resources

Science.gov (United States)

Abney, Morgan B.; Karr, Laurel; Paley, Mark S.; Donovan, David N.

2016-01-01

Oxygen recovery from metabolic carbon dioxide is an enabling capability for long-duration manned space flight. Complete recovery of oxygen (100%) involves the production of solid carbon. Catalytic approaches for this purpose, such as Bosch technology, have been limited in trade analyses due in part to the mass penalty for high catalyst resupply caused by carbon fouling of the iron or nickel catalyst. In an effort to mitigate this challenge, several technology approaches have been proposed. These approaches have included methods to prolong the life of the catalysts by increasing the total carbon mass loading per mass catalyst, methods for simplified catalyst introduction and removal to limit the resupply container mass, methods of using in situ resources, and methods to regenerate catalyst material. Research and development into these methods is ongoing, but only use of in situ resources and/or complete regeneration of catalyst material has the potential to entirely eliminate the need for resupply. The use of ionic liquids provides an opportunity to combine these methods in a technology approach designed to eliminate the need for resupply of oxygen recovery catalyst. Here we describe the results of an initial feasibility study using ionic liquids and in situ resources for life support catalyst regeneration, we discuss the key challenges with the approach, and we propose future efforts to advance the technology.

A procedure to identify and to assess risk parameters in a SCR (Steel Catenary Riser) due to the fatigue failure

Energy Technology Data Exchange (ETDEWEB)

Stefane, Wania [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Morooka, Celso K. [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Dept. de Engenharia de Petroleo. Centro de Estudos de Petroleo; Pezzi Filho, Mario [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). E and P. ENGP/IPMI/ES; Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

2009-12-19

The discovery of offshore fields in ultra deep water and the presence of reservoirs located in great depths below the seabed requires innovative solutions for offshore oil production systems. Many riser configurations have emerged as economically viable technological solutions for these scenarios. Therefore the study and the development of methodologies applied to riser design and procedures to calculate and to dimension production risers, taken into account the effects of mete ocean conditions, such as waves, current and platform motion in the fatigue failure is fundamental. The random nature of these conditions as well as the mechanical characteristics of the riser components are critical to a probabilistic treatment to ensure the greatest reliability for risers and minimum risks associated to different aspects of the operation like the safety of the installation, economical concerns and the environment. The current work presents a procedure of the identification and the assessment of main parameters of risk when considering fatigue failure. Static and dynamic behavior of Steel Catenary Riser (SCR) under the effects of mete ocean conditions and uncertainties related to total cumulative damage (Miner-Palmgren's rule) are taken into account. The methodology adopted is probabilistic and the approach is analytical. The procedure is based on the First Order Reliability Method (FORM) which usually presents low computational effort and acceptable accuracy. The procedure suggested is applied for two practical cases, one using data available from the literature and the second with data collected from an actual Brazilian offshore field operation. For both cases, results of the probability of failure due to fatigue were obtained for different locations along the SCR length connected to a semi-submersible platform. From these results, the sensitivity of the probability of failure due to fatigue for a SCR could be verified, and the most effective parameter could also be

A BGO detector for Positron Emission Profiling in catalysts

International Nuclear Information System (INIS)

Mangnus, A.V.G.; Cunningham, R.H.; Santen, R.A. van; Voigt, M.J.A. de

1995-01-01

As part of a project to study the reaction kinetics in catalysts, a detector system has been designed and built. The detector will measure in one dimension the activity distribution of positron emitters in catalyst reactors under operational conditions as a function of time. The detector consists of two arrays of ten BGO crystals each and has the flexibility to measure with high sensitivity the activity profile in various reactor sizes; the position resolution that can be reached is 3 mm. (orig.)

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.

Methanol Steam Reforming Promoted by Molten Salt-Modified Platinum on Alumina Catalysts

Science.gov (United States)

Kusche, Matthias; Agel, Friederike; Ní Bhriain, Nollaig; Kaftan, Andre; Laurin, Mathias; Libuda, Jörg; Wasserscheid, Peter

2014-01-01

We herein describe a straight forward procedure to increase the performance of platinum-on-alumina catalysts in methanol steam reforming by applying an alkali hydroxide coating according to the “solid catalyst with ionic liquid layer” (SCILL) approach. We demonstrate by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption (TPD) studies that potassium doping plays an important role in the catalyst activation. Moreover, the hygroscopic nature and the basicity of the salt modification contribute to the considerable enhancement in catalytic performance. During reaction, a partly liquid film of alkali hydroxides/carbonates forms on the catalyst/alumina surface, thus significantly enhancing the availability of water at the catalytically active sites. Too high catalyst pore fillings with salt introduce a considerable mass transfer barrier into the system as indicated by kinetic studies. Thus, the optimum interplay between beneficial catalyst modification and detrimental mass transfer effects had to be identified and was found on the applied platinum-on-alumina catalyst at KOH loadings around 7.5 mass %. PMID:25124120

Spent solid catalysts of chemical industry and petroleum refining; Les catalyseurs solides uses de l`industrie chimique et du raffinage petrolier

Energy Technology Data Exchange (ETDEWEB)

Paillier, A; Briand, Y

1997-12-31

The aim of this work is the analysis of the heterogeneous catalysis. In a first part are given the utilizing sectors. There are mainly the petroleum refining, the chemical industry and the environment. A catalyst is chosen according to its selectivity and velocity, its cost and the wastes it induces. Thus are found three main heterogeneous catalysts series: the bulky metals, the supported metals: precious or heavy or their compounds, the zeolites and other silico-aluminates. Their most frequent uses are given. The catalysts used in the main petroleum refining processes (distillation, catalytic hydro-treatment, desulfurization, catalytic reforming, catalytic cracking, catalytic hydrocracking, alkylation) are also detailed. The second part deals with the spent solid catalysts. The reasons of the deactivation (poisons or contaminants, structure modification) are given. The spent catalysts are either regenerated or eliminated. The regeneration methods are described. The solid catalysts cannot be stored without being stabilized (decrease of its water permeability and of its leachable fraction). The stabilization methods are reviewed. The regulations on the spent solid catalysts are given in the last part. (O.M.)

Spent solid catalysts of chemical industry and petroleum refining; Les catalyseurs solides uses de l`industrie chimique et du raffinage petrolier

Energy Technology Data Exchange (ETDEWEB)

Paillier, A.; Briand, Y.

1996-12-31

The aim of this work is the analysis of the heterogeneous catalysis. In a first part are given the utilizing sectors. There are mainly the petroleum refining, the chemical industry and the environment. A catalyst is chosen according to its selectivity and velocity, its cost and the wastes it induces. Thus are found three main heterogeneous catalysts series: the bulky metals, the supported metals: precious or heavy or their compounds, the zeolites and other silico-aluminates. Their most frequent uses are given. The catalysts used in the main petroleum refining processes (distillation, catalytic hydro-treatment, desulfurization, catalytic reforming, catalytic cracking, catalytic hydrocracking, alkylation) are also detailed. The second part deals with the spent solid catalysts. The reasons of the deactivation (poisons or contaminants, structure modification) are given. The spent catalysts are either regenerated or eliminated. The regeneration methods are described. The solid catalysts cannot be stored without being stabilized (decrease of its water permeability and of its leachable fraction). The stabilization methods are reviewed. The regulations on the spent solid catalysts are given in the last part. (O.M.)

High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

Science.gov (United States)

Biess, J. J.; Inouye, L. Y.; Shank, J. H.

1974-01-01

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

Toward Rational Design of Cu/SSZ-13 Selective Catalytic Reduction Catalysts: Implications from Atomic-Level Understanding of Hydrothermal Stability

Energy Technology Data Exchange (ETDEWEB)

Song, James [Institute; The; amp, Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States; Wang, Yilin [Institute; Walter, Eric D. [Environmental; Washton, Nancy M. [Environmental; Mei, Donghai [Institute; Kovarik, Libor [Environmental; Engelhard, Mark H. [Environmental; Prodinger, Sebastian [Institute; Wang, Yong [Institute; The; amp, Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States; Peden, Charles H. F. [Institute; Gao, Feng [Institute

2017-11-03

The hydrothermal stability of Cu/SSZ-13 SCR catalysts has been extensively studied, yet atomic level understanding of changes to the zeolite support and the Cu active sites during hydrothermal aging are still lacking. In this work, via the utilization of spectroscopic methods including solid-state 27Al and 29Si NMR, EPR, DRIFTS, and XPS, together with imaging and elemental mapping using STEM, detailed kinetic analyses, and theoretical calculations with DFT, various Cu species, including two types of isolated active sites and CuOx clusters, were precisely quantified for samples hydrothermally aged under varying conditions. This quantification convincingly confirms the exceptional hydrothermal stability of isolated Cu2+-2Z sites, and the gradual conversion of [Cu(OH)]+-Z to CuOx clusters with increasing aging severity. This stability difference is rationalized from the hydrolysis activation barrier difference between the two isolated sites via DFT. Discussions are provided on the nature of the CuOx clusters, and their possible detrimental roles on catalyst stability. Finally, a few rational design principles for Cu/SSZ-13 are derived rigorously from the atomic-level understanding of this catalyst obtained here. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. Computing time was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC). The experimental studies described in this paper were performed in the EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

Highly dispersed metal catalyst

Science.gov (United States)

Xiao, Xin; West, William L.; Rhodes, William D.

2016-11-08

A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

Influence of flue gas desulfurization (FGD) installations on emission characteristics of PM2.5 from coal-fired power plants equipped with selective catalytic reduction (SCR).

Science.gov (United States)

Li, Zhen; Jiang, Jingkun; Ma, Zizhen; Fajardo, Oscar A; Deng, Jianguo; Duan, Lei

2017-11-01

Flue gas desulfurization (FGD) and selective catalytic reduction (SCR) technologies have been widely used to control the emissions of sulphur dioxide (SO 2 ) and nitrogen oxides (NO X ) from coal-fired power plants (CFPPs). Field measurements of emission characteristics of four conventional CFPPs indicated a significant increase in particulate ionic species, increasing PM 2.5 emission with FGD and SCR installations. The mean concentrations of PM 2.5 from all CFPPs tested were 3.79 ± 1.37 mg/m 3 and 5.02 ± 1.73 mg/m 3 at the FGD inlet and outlet, respectively, and the corresponding contributions of ionic species were 19.1 ± 7.7% and 38.2 ± 7.8%, respectively. The FGD was found to enhance the conversion of NH 3 slip from the SCR to NH 4 + in the PM 2.5 , together with the conversion of SO 2 to SO 4 2- , and increased the primary NH 4 + and SO 4 2- aerosol emissions by approximately 18.9 and 4.2 times, respectively. This adverse effect should be considered when updating the emission inventory of CFPPs and should draw the attention of policy-makers for future air pollution control. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

Science.gov (United States)

Schryer, David R.; Upchurch, Billy T.; Hess, Robert V.; Wood, George M.; Sidney, Barry D.; Miller, Irvin M.; Brown, Kenneth G.; Vannorman, John D.; Schryer, Jacqueline; Brown, David R.

1990-01-01

Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed.

Hollow ZSM-5 encapsulated Pt nanoparticles for selective catalytic reduction of NO by hydrogen

Science.gov (United States)

Hong, Zhe; Wang, Zhong; Chen, Dan; Sun, Qiang; Li, Xuebing

2018-05-01

Pt nanoparticles were successfully encapsulated in hollow ZSM-5 single crystals by tetrapropylammonium hydroxide (TPAOH) hydrothermal treatment with an "dissolution-recrystallization" process. The prepared Pt/hollow ZSM-5 (Pt/h-ZSM-5re) sample exhibited the best activity and a maximum NO conversion of 84% can be achieved at 90 °C with N2 selectivity of 92% (GHSV = 50,000 h-1). Meanwhile, Pt/h-ZSM-5re catalyst exhibited excellent SO2, H2O resistance and durability, which was related to the stabilization of Pt active sites by hollow structure during H2-SCR. It was found that the increase of NO2 concentration in the feed gas mixture led to an activity decline. In addition, the H2-SCR reaction routes over Pt/hollow ZSM-5 catalyst at different temperature were investigated.

Effect of coke and catalyst structure on oxidative regeneration of hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E. (CANMET, Ottawa, ON (Canada). Energy Research Laboratories)

1991-04-01

Two industrial hydroprocessing catalysts used for upgrading an atmospheric residue and a gas oil, respectively were regenerated in a fixed bed using air and 2 vol.% O{sub 2}+N{sub 2} balance mixture. The regeneration in air resulted in a significant sintering of the catalyst's material. The surface area of catalysts regenerated in 2 vol.% O{sub 2} mixture was similar to that of fresh catalysts, whereas a significant loss of surface area was observed after regeneration in air. The X-ray diffraction pattern of catalysts regenerated in 2 vol.% O{sub 2}+N{sub 2} balance mixture was also similar to that of fresh catalysts. 22 refs., 9 figs., 7 tabs.

Hydroprocessing catalyst development

Energy Technology Data Exchange (ETDEWEB)

Boorman, P.M.; Kydd, R.A.; Sorensen, T.S.; Chong, K.; Lewis, J.

1992-08-01

Co-Mo and Ni-Mo hydroprocessing catalysts were examined for their activity in removal of sulfur from thiophene in model compounds, and in the cracking and hydrocracking of cumene. Three types of support materials were examined: carbon, modified carbon, and carbon covered alumina. The objective of the study was to examine the correlation between catalyst activity in the hydrodenitrogenation of model compounds, and the resistance of the catalyst to nitrogen poisoning during use in the hydroprocessing of gas oils. The use of model compound testing provided information on the individual catalytic reactions promoted by those materials. Infrared spectroscopy was used to study surface species on the catalysts and to explain many of the trends in activity observed, revealing the role of fluoride and phosphorus as a secondary promoter. Testing of the catalysts in hydrotreating of gas oils allowed comparison of model compound results with those from a real feedstock. The gas oil was also spiked with a model nitrogen compound and the results from catalytic hydrotreating of this material were compared with those from unspiked material. A key finding was that the carbon supported catalysts were the most effective in treating high-nitrogen feeds. The very favorable deactivation properties of carbon and carbon-covered alumina supported catalysts make these promising from an industrial point of view where catalyst deactivation is a limiting factor. 171 refs., 25 figs., 43 tabs.

MoO3/Al2O3 catalyst: Comparison of catalysts prepared by new slurry impregnation with molybdic acid with conventional samples

International Nuclear Information System (INIS)

Spojakina, A.; Kostova, N.; Vit, Z.; Zdrazil, M.

2003-01-01

Alumina-supported molybdena catalysts were prepared by conventional impregnation with (NH 4 ) 6 Mo 7 O 24 (CIM) and by a new slurry impregnation method (SIM). SIM is the reaction of alumina support with a slurry of MoO 3 in water. Two commercial supports were used and the commercial Mo 3 /Al 2 O 3 catalyst was included for comparison. Maximum amount of MoO 3 deposited by SIM was about 19-20 % MoO 3 with the surface area of the support of 260-280 m 2 g -1 and this corresponded to saturation monolayer of similar density as described in literature for CIM catalysts. At the ratios of MoO 3 to Al 2 O 3 in the impregnation slurry below saturation monolayer, the pH of the slurry was 3.5-6 (depending on loading) and chemical erosion of alumina is negligible. However, using the large excess of MoO 3 (35% MoO 3 ) the pH was 2.4-3.4 and chemical erosion of alumina occurred. Silica contained in alumina supports was partly extracted as soluble silicomolybdic anions during SIM. The catalysts were characterized by BET, IR, DRS (UV-vis and NIR), TPR and catalytic activity in hydrodesulfurization of thiophene. Calcination had no significant effect on the properties of SIM catalysts and this proved that calcination is not needed in that method. All catalysts exhibited features of high monolayer dispersion of molybdena and no significant difference in structure and catalytic properties was observed between SIM and CIM catalysts. This confirmed that SIM is a simple, clean and reliable method of preparation of monolayer type MoO 3 /Al 2 O 3 catalysts. (author)

Supported catalyst systems and method of making biodiesel products using such catalysts

Science.gov (United States)

Kim, Manhoe; Yan, Shuli; Salley, Steven O.; Ng, K. Y. Simon

2015-10-20

A heterogeneous catalyst system, a method of preparing the catalyst system and a method of forming a biodiesel product via transesterification reactions using the catalyst system is disclosed. The catalyst system according to one aspect of the present disclosure represents a class of supported mixed metal oxides that include at least calcium oxide and another metal oxide deposited on a lanthanum oxide or cerium oxide support. Preferably, the catalysts include CaO--CeO.sub.2ZLa.sub.2O.sub.3 or CaO--La.sub.2O.sub.3/CeO.sub.2. Optionally, the catalyst may further include additional metal oxides, such as CaO--La.sub.2O.sub.3--GdOxZLa.sub.2O.sub.3.

Endurance testing of a WDS catalyst

International Nuclear Information System (INIS)

Vladu, Mihaela; Brad, Sebastian; Vijulie, Mihai; Vasut, Felicia; Constantin, Marin

2007-01-01

the Pt high efficiency and due to the possibility of hydrophobization. During experiments carried out within this project, the Pt/C/PTFE catalyst used was manufactured from a mixture of Pt/C and Teflon, dyed onto cylindrical shape catalyst of sizes F = 2,5 mm, L = 15 mm and subsequently sintered to improve the mechanical stability. The sintering process was done into a glass equipment at 355-360 deg. C for maximum 10 min. All the experimental parameters will be acquired with a Field-Point acquisition system and the data will be modeled with the LabVIEW software. The results obtained and presented in this paper are part of project more extended. Until now the first objectives were attained, namely, designing and building of the experimental facility and manufacturing of the catalyst that will be used for endurance determinations. (authors)

The Learning School Approach and Student Proficiency in ELA and Math: Preliminary Findings. Catalyst Schools Research Study Report

Science.gov (United States)

Hammer, Patricia Cahape

2016-01-01

The Learning School initiative completed its pilot testing in June 2016, with 28 schools, called catalyst schools, taking part. Catalyst schools were located in all eight regional education service agencies (RESAs) and were supported by RESA staff in implementing the Learning School approach. Five schools had been part of the program for 2 years…

On-line alkali monitoring - Part 1; Kontinuerlig alkalimaetning - Etapp 1

Energy Technology Data Exchange (ETDEWEB)

Andersson, Christer; Ljung, P; Woxlin, H

1997-02-01

As a consequence of the increased knowledge of the environmental impact of combustion based heat and power generation, the use of renewable biofuels will be increased. An obstacle associated to biofuel combustion compared to other fuels is the large release of alkali. Alkali compounds in flue gases are known to cause severe operational problems. Three of the major problems are; fouling of superheating tubes (causing reduced heat transfer and possibly corrosion), agglomeration of the bed material in fluidized beds, and poisoning of SCR catalysts. Yet another alkali related problem arises when, in order to increase the electric efficiency of combustion power plants, combined-cycle technology is used. Alkali vapour present in the fuel gas for the gas turbine is condensed to particles which increase corrosion and erosion of the turbine blades. The research on ash related operational problems has to be extended in order to ensure future use of biofuels in heat and power generation. In all successful research, adequate tools are necessary. To investigate ash related problems the key issue is to be able to perform continuous alkali measurements. This pilot study has investigated the need of continuous alkali measurements, which alkali species are harmful in the different applications and also available instrumentation capable of measuring the specific alkali species. The report gives a short summary presenting alkali related operational problems. In addition a schematic overview is given, showing the alkali species that possibly can exist in various parts of the power plant. 48 refs, 13 figs, 4 tabs

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-30

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

High-Activity Dealloyed Catalysts

Energy Technology Data Exchange (ETDEWEB)

Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

2014-09-30

Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

Development of Molecular Catalysts to Bridge the Gap between Heterogeneous and Homogeneous Catalysts

Science.gov (United States)

Ye, Rong

Catalysts, heterogeneous, homogeneous, and enzymatic, are comprised of nanometer-sized inorganic and/or organic components. They share molecular factors including charge, coordination, interatomic distance, bonding, and orientation of catalytically active atoms. By controlling the governing catalytic components and molecular factors, catalytic processes of a multichannel and multiproduct nature could be run in all three catalytic platforms to create unique end-products. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis. Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles - some without homogeneous analogues - for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimize and expand the scope of their reactivity and selectivity. Ongoing efforts are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence and structural uniformity, dendrimers have proven to

Communicating catalysts

Science.gov (United States)

Weckhuysen, Bert M.

2018-06-01

The beauty and activity of enzymes inspire chemists to tailor new and better non-biological catalysts. Now, a study reveals that the active sites within heterogeneous catalysts actively cooperate in a fashion phenomenologically similar to, but mechanistically distinct, from enzymes.

Perturbed angular correlation study of the ion exchange of indium into silicalite zeolites

Energy Technology Data Exchange (ETDEWEB)

Ramallo-Lopez, J.M., E-mail: requejo@venus.fisica.unlp.edu.ar; Requejo, F.G., E-mail: requejo@venus.fisica.unlp.edu.ar; Renteria, M., E-mail: requejo@venus.fisica.unlp.edu.ar; Bibiloni, A.G. [UNLP, Programa TENAES (CONICET) and Departamento de Fisica, Faculdad Cs Ex (Argentina)], E-mail: requejo@venus.fisica.unlp.edu.ar; Miro, E.E. [UNL, INCAPE (CONICET) and Faculdad Ing. Quimica (Argentina)

1999-09-15

Two indium-containing silicalite zeolites (In/H-ZSM5) catalysts prepared by wet impregnation and ionic exchange were characterized by the Perturbed Angular Correlation (PAC) technique using {sup 111}In as probe to determine the nature of the indium species. Some of these species take part in the catalytic reaction of the selective reduction (SCR) of NO{sub x} with methane. PAC experiments were performed at 500 deg. C in air before and after reduction-reoxidation treatments on the catalysts in order to determine the origin of the different hyperfine interactions and then the degree of ionic exchange. Complementary catalytic activity characterizations were also performed.PAC experiments performed on the catalyst obtained by wet impregnation showed that all In-atoms form In{sub 2}O{sub 3} crystallites while almost 70% of In-atoms form In{sub 2}O{sub 3} in the catalyst obtained by ionic exchange. The PAC experiments of both catalysts performed after the reduction-reoxidation treatment revealed the presence of two hyperfine interactions, different from those corresponding to indium in In{sub 2}O{sub 3}. These hyperfine interactions should be associated to disperse In species responsible of the catalytic activity located in the ionic exchange-sites of the zeolites.

Methods of making textured catalysts

Science.gov (United States)

Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

2010-08-17

A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

In-situ hydrodeoxygenation of phenol by supported Ni catalyst-explanation for catalyst performance

DEFF Research Database (Denmark)

Wang, Ze; Zeng, Ying; Lin, Weigang

2017-01-01

In-situ hydrodeoxygenation of phenol with aqueous hydrogen donor over supported Ni catalyst was investigated. The supported Ni catalysts exerted very poor performance, if formic acid was used as the hydrogen donor. Catalyst modification by loading K, Na, Mg or La salt could not make the catalyst...... performance improved. If gaseous hydrogen was used as the hydrogen source the activity of Ni/Al2O3 was pretty high. CO2 was found poisonous to the catalysis, due to the competitive adoption of phenol with CO2. If formic acid was replaced by methanol, the catalyst performance improved remarkably, with major...... products of cyclohexanone and cyclohexanol. The better effect of methanol enlightened the application of the supported Ni catalyst in in-situ hydrodeoxygenation of phenol....

Non-PGM cell catalysts

Energy Technology Data Exchange (ETDEWEB)

Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Elvington, M. [Savannah River Consulting, Aiken, SC (United States); Ganesan, P. [Savannah River Consulting, Aiken, SC (United States)

2017-09-27

A unique approach has been developed to probe the non-PGM catalyst active site for the Oxygen Reduction Reaction (ORR) for PEMFCs. Iron based functionalities have been engineered into a variety of catalysts to evaluate their impact on activity for the ORR. A series of high surface area catalysts were synthesized and the impact of the chemical structure on the electrochemical and electrocatalytic properties was investigated. Elemental and surface analyses of the prepared catalysts reveal the incorporation of iron in a targeted and controlled manner. A high surface area framework catalyst was prepared that shows exceptional activity, comparable to state-of-the-art materials. The results of this research project provided critical seed data for the newly awarded ElectroCat project, which focuses on rationally designed framework catalysts for the oxygen reduction reaction.

Alloy catalyst material

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...... of the novel catalyst material for synthesising hydrogen peroxide from oxygen and hydrogen, or from oxygen and water....

Thermal conductivity of catalyst layer of polymer electrolyte membrane fuel cells: Part 1 - Experimental study

Science.gov (United States)

Ahadi, Mohammad; Tam, Mickey; Saha, Madhu S.; Stumper, Jürgen; Bahrami, Majid

2017-06-01

In this work, a new methodology is proposed for measuring the through-plane thermal conductivity of catalyst layers (CLs) in polymer electrolyte membrane fuel cells. The proposed methodology is based on deconvolution of bulk thermal conductivity of a CL from measurements of two thicknesses of the CL, where the CLs are sandwiched in a stack made of two catalyst-coated substrates. Effects of hot-pressing, compression, measurement method, and substrate on the through-plane thermal conductivity of the CL are studied. For this purpose, different thicknesses of catalyst are coated on ethylene tetrafluoroethylene (ETFE) and aluminum (Al) substrates by a conventional Mayer bar coater and measured by scanning electron microscopy (SEM). The through-plane thermal conductivity of the CLs is measured by the well-known guarded heat flow (GHF) method as well as a recently developed transient plane source (TPS) method for thin films which modifies the original TPS thin film method. Measurements show that none of the studied factors has any effect on the through-plane thermal conductivity of the CL. GHF measurements of a non-hot-pressed CL on Al yield thermal conductivity of 0.214 ± 0.005 Wṡm-1ṡK-1, and TPS measurements of a hot-pressed CL on ETFE yield thermal conductivity of 0.218 ± 0.005 Wṡm-1ṡK-1.

Vibration measurements of automobile catalyst

Science.gov (United States)

Aatola, Seppo

1994-09-01

Vibration of catalyst cell, which is inside the casing of the catalyst, is difficult to measure with usual measuring instrumentation. When catalyst is in use, there is hot exhaust gas flow though the catalyst cell and temperature of the cell is approximately +900 degree(s)C. Therefore non-contact Laser- Doppler-Vibrometer was used to measure vibration velocity of the catalyst cell. The laser beam was directed towards the cell through pipe which was put through and welded to the casing of the catalyst. The outer end of the pipe was screw down with a tempered class to prevent exhaust gas flow from the pipe. The inner end of the pipe was open and few millimeters away from the measuring point. Catalyst was attached to the engine with two ways, rigidly close to the engine and flexible under the engine. The engine was running in test bench under controlled conditions. Vibration measurements were carried out during constant running speeds of the engine. Vibration signals were captured and analyzed with FFT-analyzer. Vibration of catalyst cell was strongest at running speed of 5000 rpm, from 10 to 20 g (1 g equals 9.81 ms-2), when catalyst was attached rigidly close to the engine. At running speed of 3000 rpm, vibration of catalyst cell was from 2 to 3 g in most cases, when catalyst was attached either rigidly or flexible to the engine. It is estimated that in real life, i.e. when catalyst is attached to car with same engine, vibration of catalyst cell at running speed of 5000 rpm is somewhere between 1 and 10 g. At running speed of 3000 rpm, which may be more often used when driving car (car speed approximately 100 kmh-1), vibration of catalyst cell is probably few g's.

Catalyst for microelectromechanical systems microreactors

Science.gov (United States)

Morse, Jeffrey D [Martinez, CA; Sopchak, David A [Livermore, CA; Upadhye, Ravindra S [Pleasanton, CA; Reynolds, John G [San Ramon, CA; Satcher, Joseph H [Patterson, CA; Gash, Alex E [Brentwood, CA

2010-06-29

A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

Catalysts for Efficient Production of Carbon Nanotubes

Science.gov (United States)

Sun, Ted X.; Dong, Yi

2009-01-01

Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

Intermediate Ethanol Blends Catalyst Durability Program

Energy Technology Data Exchange (ETDEWEB)

West, Brian H; Sluder, Scott; Knoll, Keith; Orban, John; Feng, Jingyu

2012-02-01

In the summer of 2007, the U.S. Department of Energy (DOE) initiated a test program to evaluate the potential impacts of intermediate ethanol blends (also known as mid-level blends) on legacy vehicles and other engines. The purpose of the test program was to develop information important to assessing the viability of using intermediate blends as a contributor to meeting national goals for the use of renewable fuels. Through a wide range of experimental activities, DOE is evaluating the effects of E15 and E20 - gasoline blended with 15% and 20% ethanol - on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials. This report provides the results of the catalyst durability study, a substantial part of the overall test program. Results from additional projects will be reported separately. The principal purpose of the catalyst durability study was to investigate the effects of adding up to 20% ethanol to gasoline on the durability of catalysts and other aspects of the emissions control systems of vehicles. Section 1 provides further information about the purpose and context of the study. Section 2 describes the experimental approach for the test program, including vehicle selection, aging and emissions test cycle, fuel selection, and data handling and analysis. Section 3 summarizes the effects of the ethanol blends on emissions and fuel economy of the test vehicles. Section 4 summarizes notable unscheduled maintenance and testing issues experienced during the program. The appendixes provide additional detail about the statistical models used in the analysis, detailed statistical analyses, and detailed vehicle specifications.

Regeneration of Hydrotreating and FCC Catalysts

Energy Technology Data Exchange (ETDEWEB)

CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

1999-09-30

Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

Propylene oxidation on catalytic Pt-Cu/y alumina. (Part II) chemical Kinetics of catalysts of Pt-Cu/y-alumina in the propylene oxidation

International Nuclear Information System (INIS)

Carballo, Luis M; Zea, Hugo R

1999-01-01

In this work is treated the effect of the composition of catalysts of Pt-Cu/y - alumina on the specific superficial activity corresponding to the total oxidation of propylene. Although the catalyst activity of the Cu in the operation conditions went practically null the specific activity of the catalytic Pt-Cu it incremented with the increase of the contained proportion of Cu in the catalyst. The total global speed by gram of catalyst was also increased with the introduction of Cu, but only to medium and high concentrations of propylene. The specific superficial activity was bigger for the sinterizated catalyst, for a given composition of the bimetallic catalyst, compared with that of the fresh catalyst (non-sinterizated). To explain, the catalytic behavior of the propylene oxidation, on the catalysts here studied, it is postulated that the propylene molecule it absorb with less force on the faces than in the corners or borders of the crystals of the catalyst and that the connection of adsorption on a place of given Pt is affected by the atoms of neighboring Cu on the surface causing changes in the mobility of the absorbed species. The kinetic results reveal a complex dependence between the reaction speed and the concentration of the propylene. In low concentrations of propylene the reaction speed was increased until to reach a maximum, and then to continue with a marked decreasing; and to concentrations. In bigger propylene concentrations, the reaction kinetics is presented as zero order with regard to the propylene, for some given concentrations of oxygen

Part II: Oxidative Thermal Aging of Pd/Al2O3 and Pd/CexOy-ZrO2 in Automotive Three Way Catalysts: The Effects of Fuel Shutoff and Attempted Fuel Rich Regeneration

Directory of Open Access Journals (Sweden)

Qinghe Zheng

2015-10-01

Full Text Available The Pd component in the automotive three way catalyst (TWC experiences deactivation during fuel shutoff, a process employed by automobile companies for enhancing fuel economy when the vehicle is coasting downhill. The process exposes the TWC to a severe oxidative aging environment with the flow of hot (800 °C–1050 °C air. Simulated fuel shutoff aging at 1050 °C leads to Pd metal sintering, the main cause of irreversible deactivation of 3% Pd/Al2O3 and 3% Pd/CexOy-ZrO2 (CZO as model catalysts. The effect on the Rh component was presented in our companion paper Part I. Moderate support sintering and Pd-CexOy interactions were also experienced upon aging, but had a minimal effect on the catalyst activity losses. Cooling in air, following aging, was not able to reverse the metallic Pd sintering by re-dispersing to PdO. Unlike the aged Rh-TWCs (Part I, reduction via in situ steam reforming (SR of exhaust HCs was not effective in reversing the deactivation of aged Pd/Al2O3, but did show a slight recovery of the Pd activity when CZO was the carrier. The Pd+/Pd0 and Ce3+/Ce4+ couples in Pd/CZO are reported to promote the catalytic SR by improving the redox efficiency during the regeneration, while no such promoting effect was observed for Pd/Al2O3. A suggestion is made for improving the catalyst performance.

Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

Science.gov (United States)

Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

2017-11-01

A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

Novel catalysts and photoelectrochemical system for solar fuel production

Science.gov (United States)

Zhang, Yan

Solar fuel production from abundant raw chemicals such as CO2 and water is highly desired as a clean renewable energy solution for the future. Developing photoelectrochemical cells is viewed as a promising approach to realize this energy conversion and storage process. Efficient and robust oxygen evolution catalyst made from non-precious materials remains a major challenge for such a system. This thesis basically consists of three parts of work, including studies on enhancing the photocatalytic oxygen evolution activity of cobalt-based spinel nanoparticles by manganese3+ substitution, in situ formation of cobalt oxide nanocubanes as highly active catalyst for photocatalytic oxygen evolution reaction, and development of a photoanode-driven photoelectrochemical cell for CO2 reduction with water. The first part of this thesis work devotes efforts in the development and study on cobalt and other transition metal oxide based oxygen evolution catalyst. Photocatalytic oxygen evolution is a critical step for solar fuel production from abundant sources. It poses a significant challenge because it requires an efficient catalyst to bridge the one-electron photon capture process with the four-electron oxygen reaction. Among all the metal oxides, Co3O4 spinel exhibits a high activity as an oxygen evolution catalyst. The results of this work demonstrate that the photocatalytic oxygen evolution activity of Co3O4 spinel can be further enhanced by substituting Co with Mn in the spinel structure. Using a facile hydrothermal approach, Co3O4 spinel nanoparticles as well as Mn-substituted and Ni-substituted Co3O4 spinel nanoparticles with a typical particle size of 5-7 nm were successfully synthesized. The morphology and crystal structures of the as-synthesized nanoparticle catalysts have been carefully examined using various structural characterization techniques, including powder x-ray diffraction (PXRD), transmission electron microscope (TEM), gas adsorption, and x-ray absorption

Templating Routes to Supported Oxide Catalysts by Design

Energy Technology Data Exchange (ETDEWEB)

Notestein, Justin M. [Northwestern Univ., Evanston, IL (United States)

2016-09-08

The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas. First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MO_x-SiO₂ catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing ‘nanocavities’ from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO₂-Al₂O₃ acid catalysts and to control reactant selectivity in Al₂O₃-TiO₂ photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported

Catalysts for synthetic liquid fuels

Energy Technology Data Exchange (ETDEWEB)

Bruce, L.A.; Turney, T.W.

1987-12-01

Fischer-Tropsch catalysts have been designed, characterized and tested for the selective production of hydrocarbons suitable as synthetic liquid transport fuels from synthesis gas (i.e., by the reduction of carbon monoxide with hydrogen). It was found that hydrocarbons in the middle distillate range, or suitable for conversion to that range, could be produced over several of the new catalyst systems. The various catalysts examined included: (1) synthetic cobalt clays, mainly cobalt chlorites; (2) cobalt hydrotalcites; (3) ruthenium metal supported on rare earth oxides of high surface area; and (4) a novel promoted cobalt catalyst. Active and selective catalysts have been obtained, in each category. With the exception of the clays, reproducibility of catalyst performance has been good. Catalysts in groups 2 and 4 have exhibited very high activity, with long lifetimes and easy regeneration.

Synthesis H-Zeolite catalyst by impregnation KI/KIO3 and performance test catalyst for biodiesel production

Science.gov (United States)

Widayat, W.; Rizky Wicaksono, Adit; Hakim Firdaus, Lukman; Okvitarini, Ndaru

2016-02-01

The objective of this research is to produce H-catalyst catalyst that was impregnated with KI/KIO3. The catalyst was analyzed about surface area, X-Ray Diffraction (XRD) and performance test of catalyst for biodiesel production. An H-Zeolite catalyst was synthesized from natural zeolite with chemical treatment processing, impregnation KI/KIO3 and physical treatment. The results shows that the surface area of the catalyst by 27.236 m2/g at a concentration of 5% KI. XRD analysis shows peak 2-θ at 23.627o indicating that KI was impregnated on H-zeolite catalyst. The catalyst was tested in production of biodiesel using palm oil with conventional methods for 3 hour at temperature of 70-80 oC. The result for conversion Fatty Acid Methyl Ester (FAME) reached maximum value on 87.91% under production process using catalyst 5% KIO3-H zeolite.

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

International Nuclear Information System (INIS)

Amende, Max; Kaftan, Andre; Bachmann, Philipp; Brehmer, Richard; Preuster, Patrick; Koch, Marcus

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al_2O_3 model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al_2O_3 catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al_2O_3 model catalyst and core–shell pellet were only

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

Energy Technology Data Exchange (ETDEWEB)

Amende, Max, E-mail: max.amende@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Kaftan, Andre, E-mail: andre.kaftan@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Bachmann, Philipp, E-mail: philipp.bachmann@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Brehmer, Richard, E-mail: richard.brehmer@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Preuster, Patrick, E-mail: patrick.preuster@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Koch, Marcus, E-mail: marcus.koch@crt.cbi.uni-erlangen.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); and others

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al{sub 2}O{sub 3} model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al{sub 2}O{sub 3} catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al{sub 2}O{sub 3} model catalyst and

Predicting mercury retention in utility gas cleaning systems with SCR/ESP/FGD combinations or activated carbon injection

Energy Technology Data Exchange (ETDEWEB)

Krishnakumar, Balaji; Naik, Chitralkumar V.; Niksa, Stephen [Niksa Energy Associates LLC, Belmont, CA (United States); Fujiwara, Naoki [Idemitsu Kosan Co., Ltd, Chiba (Japan). Coal and Environment Research Lab.

2013-07-01

This paper presents validations of the Hg speciation predicted by NEA's MercuRator trademark package with an American field test database for 28 full-scale utility gas cleaning systems. It emphasizes SCR/ESP/FGD combinations and activated carbon injection because these two applications present the best long- term prospects for Hg control by coal-burning utilities. Validations of the extents of Hg{sup 0} oxidation across SCRs and of Hg retention in wet FGDs gave correlation coefficients greater than 0.9 for both units. A transport-based FGD analysis correctly assessed the potential for Hg{sup 0} re-emission in one limestone wet FGD. Among the ten stations in the SCR/ESP/FGD validations, the simulations correctly identified 3 of 4 of the relatively high Hg emissions rates; all four of the sites with moderate emissions rates; and both sites with the lowest emission rates. The validations for ACI applications demonstrated that Hg removals can be accurately estimated for the full domain of coal quality, LOI, and ACI rates for both untreated and brominated carbon sorbents. The predictions for ACI depict the test-to-test variations in most cases, and accurately describe the impact of ACI configuration and sorbent type. ACI into FFs is the most effective configuration, although ACI into ESPs often removes 90% or more Hg, provided that there is sufficient residence time and Cl in the flue gas. Brominated sorbents perform better than untreated carbons, unless SO{sub 3} condensation inhibits Hg adsorption.

Exhaust particle and NOx emission performance of an SCR heavy duty truck operating in real-world conditions

Science.gov (United States)

Saari, Sampo; Karjalainen, Panu; Ntziachristos, Leonidas; Pirjola, Liisa; Matilainen, Pekka; Keskinen, Jorma; Rönkkö, Topi

2016-02-01

Particle and NOx emissions of an SCR equipped HDD truck were studied in real-world driving conditions using the "Sniffer" mobile laboratory. Real-time CO2 measurement enables emission factor calculation for NOx and particles. In this study, we compared three different emission factor calculation methods and characterised their suitability for real-world chasing experiments. The particle number emission was bimodal and dominated by the nucleation mode particles (diameter below 23 nm) having emission factor up to 1 × 1015 #/kgfuel whereas emission factor for soot (diameter above 23 nm that is consistent with the PMP standard) was typically 1 × 1014 #/kgfuel. The effect of thermodenuder on the exhaust particles indicated that the nucleation particles consisted mainly of volatile compounds, but sometimes there also existed a non-volatile core. The nucleation mode particles are not controlled by current regulations in Europe. However, these particles consistently form under atmospheric dilution in the plume of the truck and constitute a health risk for the human population that is exposed to those. Average NOx emission was 3.55 g/kWh during the test, whereas the Euro IV emission limit over transient testing is 3.5 g NOx/kWh. The on-road emission performance of the vehicle was very close to the expected levels, confirming the successful operation of the SCR system of the tested vehicle. Heavy driving conditions such as uphill driving increased both the NOx and particle number emission factors whereas the emission factor for soot particle number remains rather constant.

Studies in transition metal chemistry ; V. Soluble Ziegler-type catalysts based on vanadium, part 1

NARCIS (Netherlands)

Liefde Meijer, H.J. de; Hurk, J.W.G. van den; Kerk, G.J.M. van der

1966-01-01

Experiments are described aiming at a simplification of the catalyst system originally consisting of a mixture of tetraphenyltin, aluminium bromide and vanadium tetrachloride (or vanadium oxytrichloride). It is shown that tetraphenyltin merely acts as a phenylating agent for the aluminium bromide

Catalyst in Basic Oleochemicals

Directory of Open Access Journals (Sweden)

Eva Suyenty

2007-10-01

Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6

Effect of Radiotherapy Volume and Dose on Secondary Cancer Risk in Stage I Testicular Seminoma

International Nuclear Information System (INIS)

Zwahlen, Daniel R.; Martin, Jarad M.; Millar, Jeremy L.; Schneider, Uwe

2008-01-01

Purpose: To estimate and compare the secondary cancer risk (SCR) due to para-aortic (PA), dogleg field (DLF), or extensive field (EF) radiotherapy (RT) at different dose levels for Stage I testicular seminoma. Methods and Materials: The organ equivalent dose concept with a linear, plateau, and linear-exponential dose-response model was applied to the dose distributions to estimate the SCR. The dose distributions were calculated in a voxel-based anthropomorphic phantom. Three different three-dimensional plans were computed: PA, DLF, and EF. The plans were calculated with 6-MV photons and two opposed fields, using 20 Gy in 10 fractions. Results: The estimated cumulative SCR for a 75-year-old patient treated with PA-RT at age 35 was 23.3% (linear model), 20.9% (plateau model), and 20.8% (linear-exponential model) compared with 19.8% for the general population. Dependent on the model, PA-RT compared with DLF-RT reduced the SCR by 48-63% or 64-69% when normalized to EF-RT. For PA-RT, the linear dose-response model predicted a decrease of 45% in the SCR, using 20 Gy instead of 30 Gy; the linear-exponential dose-response model predicted no change in SCR. Conclusion: Our model suggested that the SCR after PA-RT for Stage I testicular seminoma is reduced by approximately one-half to two-thirds compared with DLF-RT, independent of the dose-response model. The SCR is expected to be equal or lower with 20 Gy than with 30 Gy. In the absence of mature patient data, the organ equivalent dose concept offers the best potential method of estimating the SCR when discussing treatment options with patients

Diagnosis of Catalyst Cooler and Riser in RFCC using Sealed gamma-ray Source

International Nuclear Information System (INIS)

Kim, Jin Seop; Kim, Jong Bum; Jung, Sung Hee; Kim, Jae Ho

2005-12-01

With a quantitative growth of the petroleum industry, a lot of budget are spent for the maintenance and repairs of facilities related to the process annually. Among them, the RFCC(residual fluid catalytic cracking) is a highly value-added unit which converts gas oil and heavier streams to lighter, more valuable products such as propylene, gasoline by an injection of atmospheric residue into the fluided catalyst. In this study, field experiments were performed to analyze the reasons of an abnormal operation in the catalyst cooler and the catalyst riser belonged to the RFCC unit respectively and to estimate the amount of seriousness using sealed gamma-ray source( 60 Co). The catalyst cooler functions cooling for the regeneration of a catalyst, which will be used to a new media in the RFCC unit. The catalyst riser, while, plays an important part in transporting to next cyclotron steps by mixing of an oil, steam and a catalyst mechanically. The purposes of this study is what was the condition of catalyst flow pattern and whether the coke was produced in an inside process or not. Gamma radiation counts were measured by the detector(NaI) positioned outside the pipe-wall diametrically opposite to the gamma source with a regular space. From the results, the section different from the distribution pattern of nearby catalyst in a facility was found. And this became the definitive information to a process operator. Diagnosis technique using gamma radiation source is proved to be the effective and reliable method in providing information on the media distribution in a facility

In-situ characterization of heterogeneous catalysts

CERN Document Server

Rodriguez, Jose A; Chupas, Peter J

2013-01-01

Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

Reuse of Hydrotreating Spent Catalyst

International Nuclear Information System (INIS)

Habib, A.M.; Menoufy, M.F.; Amhed, S.H.

2004-01-01

All hydro treating catalysts used in petroleum refining processes gradually lose activity through coking, poisoning by metal, sulfur or halides or lose surface area from sintering at high process temperatures. Waste hydrotreating catalyst, which have been used in re-refining of waste lube oil at Alexandria Petroleum Company (after 5 years lifetime) compared with the same fresh catalyst were used in the present work. Studies are conducted on partial extraction of the active metals of spent catalyst (Mo and Ni) using three leaching solvents,4% oxidized oxalic acid, 10% aqueous sodium hydroxide and 10% citric acid. The leaching experiments are conducting on the de coked extrude [un crushed] spent catalyst samples. These steps are carried out in order to rejuvenate the spent catalyst to be reused in other reactions. The results indicated that 4% oxidized oxalic acid leaching solution gave total metal removal 45.6 for de coked catalyst samples while NaOH gave 35% and citric acid gave 31.9 % The oxidized leaching agent was the most efficient leaching solvent to facilitate the metal removal, and the rejuvenated catalyst was characterized by the unchanged crystalline phase The rejuvenated catalyst was applied for hydrodesulfurization (HDS) of vacuum gas oil as a feedstock, under different hydrogen pressure 20-80 bar in order to compare its HDS activity

Sodium Tetraphenylborate Catalyst Identification: Preliminary Studies Set 2

International Nuclear Information System (INIS)

Barnes, M.J.

1997-05-01

This document details the results of these tests and represents the second report of the task designed to identify soluble NaTPB decomposition catalysts. This task, performed as part of the DNFSB Recommendation 96-1 Implementation Plan, partially fulfills the request by High Level Waste Engineering and the ITP Flow Sheet Team in task Technical Request HLW-TTR-97008

Soot oxidation over NOx storage catalysts. Activity and deactivation

International Nuclear Information System (INIS)

Krishna, K.; Makkee, M.

2006-01-01

Soot oxidation activity and deactivation of NO x storage and reduction (NSR) catalysts containing Pt, K, and Ba supported on Al 2 O 3 , are studied under a variety of reaction conditions. K-containing catalysts decrease soot oxidation temperature with O 2 alone and the presence of Pt further enhance the activity due to synergetic effect. The active species responsible for synergism on Pt/K-Al 2 O 3 are unstable and cannot be regenerated. Soot oxidation temperature decreases by about 150 o C with NO+O 2 exhaust feed gas and under lean conditions NSR system acts as catalysed soot filter (CSF). The reactions that are mainly responsible for decreasing soot oxidation temperature are: (1) soot oxidation with NO 2 followed by NO recycles to NO 2 , and (2) soot oxidation with O 2 assisted by NO 2 . Only a part of the stored NO x that is decomposed at high temperatures under lean conditions is found to be useful for soot oxidation. NO x storage capacity of NSR catalysts decreases upon ageing under soot oxidising conditions. This will lead to a decreased soot oxidation activity on stored nitrate decomposition. Pt/K-Al 2 O 3 catalyst is more active, but least stable compared with Pt/Ba-Al 2 O 3 . (author)

ALKALI RESISTANT CATALYST

DEFF Research Database (Denmark)

2008-01-01

The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

Developing the multiple stress-strain creep recovery (MS-SCR) test

Science.gov (United States)

Elnasri, Mahmoud; Airey, Gordon; Thom, Nick

2018-04-01

While most published work from Europe has been concerned with evaluating binders' resistance to rutting based on their stiffness (deformation resistance), work originating in the US has mainly been concerned with ranking binders based on their recoverability in a multiple stress form. This paper details the design of a new modified multiple stress-strain creep recovery (MS-SCR) test. The test is designed to evaluate binders' rutting resistance based on two rutting resistance mechanisms: stiffness and recoverability. A preliminary investigation is presented in this paper followed by details of the design of the new modified test. A 40/60 penetration grade bitumen and bitumen-filler mastics prepared with three filler concentrations (35%, 50%, and 65% filler content by mass of mastic) were tested. In addition, two polymer modified bitumens (PMBs) using the same base bitumen type were examined for validation. Two parameters are introduced to characterise the short and long recovery in the new test. In terms of stiffness, the test allows the behaviour of binders at different stress levels and loading cycles to be studied and produces a new parameter that can quantify the degree of modification. Finally, a relationship between nonlinearity and normal force in the test was investigated.

Paraffin Alkylation Using Zeolite Catalysts in a slurry reactor: Chemical Engineering Principles to Extend Catalyst Lifetime

NARCIS (Netherlands)

Jong, K.P. de; Mesters, C.M.A.M.; Peferoen, D.G.R.; Brugge, P.T.M. van; Groot, C. de

1996-01-01

The alkylation of isobutane with 2-butene is carried out using a zeolitic catalyst in a well stirred slurry reactor. Whereas application of fixed bed technology using a solid acid alkylation catalyst has in the led to catalysts lifetimes in the range of minutes, in this work we report catalyst

Hydroxide catalysts for lignin depolymerization

Science.gov (United States)

Beckham, Gregg T; Biddy, Mary J.; Kruger, Jacob S.; Chmely, Stephen C.; Sturgeon, Matthew

2017-10-17

Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

Hydroxide catalysts for lignin depolymerization

Energy Technology Data Exchange (ETDEWEB)

Beckham, Gregg T.; Biddy, Mary J.; Chmely, Stephen C.; Sturgeon, Matthew

2017-04-25

Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

Solvent-free and catalyst-free chemistry: A benign pathway to sustainability

Science.gov (United States)

In the past decade, alternative benign organic methodologies have become an imperative part of organic syntheses and novel chemical reactions. The various new and innovative sustainable organic reactions and methodologies using no solvents or catalysts and employing alternative ...

Hydrous titanium oxide-supported catalysts

International Nuclear Information System (INIS)

Dosch, R.G.; Stohl, F.V.; Richardson, J.T.

1990-01-01

Catalysts were prepared on hydrous titanium oxide (HTO) supports by ion exchange of an active metal for Na + ions incorporated in the HTO support during preparation by reaction with the parent Ti alkoxide. Strong active metal-HTO interactions as a result of the ion exchange reaction can require significantly different conditions for activation as compared to catalysts prepared by more widely used incipient wetness methods. The latter catalysts typically involve conversion or while the HTO catalysts require the alteration of electrostatic bonds between the metal and support with subsequent alteration of the support itself. In this paper, the authors discuss the activation, via sulfidation or reduction, of catalysts consisting of Co, Mo, or Ni-Mo dispersed on HTO supports by ion exchange. Correlations between the activation process and the hydrogenation, hydrodeoxygenation, and hydrodesulfurization activities of the catalysts are presented

Methanol conversion to hydrocarbons using modified clinoptilolite catalysts. Investigation of catalyst lifetime and reactivation

Energy Technology Data Exchange (ETDEWEB)

Hutchings, G J; Themistocleous, T; Copperthwaite, R G

1988-10-17

A study of the deactivation and reactivation of modified clinoptilolite catalysts for methanol conversion to hydrocarbons is reported. Clinoptilolite catalysts, modified by either ammonium ion exchange or hydrochloric acid treatment, exhibit a short useful catalyst lifetime for this reaction (ca. 2-3 h) due to a high rate of coke deposition (3-5.10/sup -3/ g carbon/g catalyst/h). A comparative study of reactivation using oxygen, nitrous oxide and ozone/oxygen as oxidants indicated that nitrous oxide reactivation gives improved catalytic performance when compared to the activity and lifetime of the fresh catalyst. Both oxygen and ozone/oxygen were found to be ineffective for the reactivation of clinoptilolite. Initial studies of in situ on-line reactivation are also described. 3 figs., 15 refs., 4 tabs.

Magnetic catalyst bodies

NARCIS (Netherlands)

Teunissen, Wendy; Bol, A.A.; Geus, John W.

1999-01-01

After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the

How best management practices affect emissions in gas turbine power plants - an important factor to consider when strengthening emission standards.

Science.gov (United States)

Zeng, Jinghai; Xing, Min; Hou, Min; England, Glenn C; Yan, Jing

2018-04-27

The Beijing Municipal Environmental Protection Bureau (EPB) is considering strengthening the Emission Standard of Air Pollutants for Stationary Gas Turbines, originally published in 2011 (DB11/847-2011), with a focus on reducing nitrogen oxides (NOx) emissions. A feasibility study was conducted to evaluate the current operation of twelve (12) existing combined-cycle gas turbine power plants and the design of two (2) new plants in Beijing and their emission reduction potential, in comparison with a state-of-the-art power plant in California, United States. The study found that Best Management Practices (BMPs) could potentially improve the emission level of the power plants, and should be implemented to minimize emissions under current design characteristics. These BMPs include (1) more frequent tuning of turbine combustors; (2) onsite testing of natural gas characteristics in comparison to turbine manufacturer's specifics and tuning of turbine to natural gas quality; (3) onsite testing of aqueous ammonia to ensure adequate ammonia concentration in the mixed solution, and the purity of the solution; (4) more careful inspection of the heat recovery steam generator (HRSG), and the selective catalytic reduction (SCR) during operation and maintenance; (5) annual testing of the catalyst coupon on the SCR to ensure catalyst effectiveness; and (6) annual ammonia injection grid (AIG) tuning. The study found that without major modification to the plants, improving the management of the Beijing gas turbine power plants may potentially reduce the current hourly-average NOx emission level of 5-10 parts per million (ppm, ranges reflects plant variation) by up to 20%. The exact improvement associated with each BMP for each facility requires more detailed analysis, and requires engagement of turbine, HRSG, and SCR manufacturers. This potential improvement is an important factor to consider when strengthening the emission standard. However it is to be noted that with the continuous

Catalytic conversion of CO, NO and SO2 on supported sulfide catalysts. Part 2. Catalytic reduction of NO and SO2 by CO

International Nuclear Information System (INIS)

Zhuang, S.-X.; Yamazaki, M.; Omata, K.; Takahashi, Y.; Yamada, M.

2001-01-01

To investigate the possibility of simultaneous catalytic reduction of NO and SO 2 by CO, reactions of NO, NO-CO, and NO-SO 2 -CO were performed on γ-alumina-supported sulfides of transition metals including Co, Mo, CoMo and FeMo. NO was decomposed into N 2 O and N 2 accompanied with the formation of SO 2 ; this serious oxidation of lattice sulfur resulted in the deactivation of the catalysts. The addition of CO to the NO stream suppressed SO 2 formation and yielded COS instead. A stoichiometric conversion of NO and CO to N 2 and CO 2 was observed above 350C on the CoMo and the FeMo catalysts. Although the CO addition lengthened catalyst life, it was not enough to maintain activity. After the NO-CO reaction, an XPS analysis showed the growth of Mo 6+ and SO 4 2- peaks, especially for the sulfided FeMo/Al 2 O 3 ; the FeMo catalyst underwent strong oxidation in the NO-CO reaction. The NO and the NO-CO reactions proceeded non-catalytically, consuming catalyst lattice sulfur to yield SO 2 or COS. The addition of SO 2 in the NO-CO system enabled in situ regeneration of the catalysts; the catalysts oxidized through abstraction of lattice sulfur experienced anew reduction and sulfurization through the SO 2 -CO reaction at higher temperature. NO and SO 2 were completely and catalytically converted at 400C on the sulfided CoMo/Al 2 O 3 . By contrast, the sulfided FeMo/Al 2 O 3 was easily oxidized by NO and hardly re-sulfided under the test conditions. Oxidation states of the metals before and after the reactions were determined. Silica and titania-supported CoMo catalysts were also evaluated to study support effects

Hydrogenation of aromatic compounds during gas oil hydrodewaxing. Part 1. Effect of ruthenium content and method of nickel catalyst preparation

Energy Technology Data Exchange (ETDEWEB)

Masalska, Aleksandra [Wroclaw University of Technology, Faculty of Chemistry, 7/9 Gdanska Street, 50-344 Wroclaw (Poland)

2008-09-30

Ni-based (8 wt.% NiO) dewaxing catalysts for the hydroconversion of the hydroraffinate of oil fraction (d{sub 20} {sub C} = 0.845 g/cm{sup 3}; cloud point (CP) -2 C; aromatics = 25.8 wt.%; S = 25 ppm) were modified with Ru. The effect of Ru content (0.6, 0.75 and 0.9 wt.% of RuO{sub 2}) and the methods of Ni catalyst preparation were examined. The catalysts were characterised by N{sub 2} sorption, TPR, ICP, XRD, SEM, XPS, H{sub 2} chemisorption. Activity was tested in a continuous-flow system at 6 MPa (LHSV, 2.5 h{sup -1}; H{sub 2}:CH, 350 N m{sup 3}/m{sup 3}). NiO and RuO{sub 2} were found to exert a synergic effect on catalytic activity. The rise in RuO{sub 2} content from 0.6 to 0.9 wt.% increased the HDA of HON from 23 to 65% at 240 C and was parallelled by a drop in CP (by about 15 C). The effect of Ru was found to depend on the method of Ni catalyst preparation. (author)

H2 assisted NH3-SCR over Ag/Al2O3 for automotive applications

DEFF Research Database (Denmark)

Fogel, Sebastian

-BEA can give a high NOx conversion in a broad temperature window without the need to dose H2 at higher temperatures. The aim of this study has been to investigate the combined Ag/Al2O3 and Fe-BEA catalyst system both at laboratory-scale and in full-scale enginebench testing. The catalysts were combined...... both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al2O3 catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study...... the layers allowing diffusion of reaction intermediates between them. Ag/Al2O3 only and the combined Ag/Al2O3 – Fe-BEA systems were active during the transient NEDC. The NOx conversions were not very high which is related to the very low temperature of the NEDC and the lower than expected activity of the Ag...

Development of GREET Catalyst Module

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division

2014-09-01

Catalysts are critical inputs for many pathways that convert biomass into biofuels. Energy consumption and greenhouse gas (GHG) emissions during the production of catalysts and chemical inputs influence the life-cycle energy consumption, and GHG emissions of biofuels and need to be considered in biofuel life-cycle analysis (LCA). In this report, we develop energy and material flows for the production of three different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5]) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module. They were selected because they are consumed in existing U.S. Department of Energy (DOE) analyses of biofuel processes. For example, a thermochemical ethanol production pathway (indirect gasification and mixed alcohol synthesis) developed by the National Renewable Energy Laboratory (NREL) uses olivine, DEPG, and tar reforming and alcohol synthesis catalysts (Dutta et al., 2011). ZSM-5 can be used in biofuel production pathways such as catalytic upgrading of sugars into hydrocarbons (Biddy and Jones, 2013). Other uses for these compounds and catalysts are certainly possible. In this report, we document the data sources and methodology we used to develop material and energy flows for the catalysts and compounds in the GREET catalyst module. In Section 2 we focus on compounds used in the model Dutta et al. (2011) developed. In Section 3, we report material and energy flows associated with ZSM-5 production. Finally, in Section 4, we report results.

Conversion of bio-feedstocks through acid and basic zeolites and catalysts

Energy Technology Data Exchange (ETDEWEB)

Buzzoni, R.; Bosetti, A.; Delledonne, D.; Perego, C. [eni S.p.A. Research Centre for Non-Conventional Energy, Novara (Italy). Ist. eni Donegani

2012-07-01

Not far in the future, a significant part of fuels and chemicals will be originated by renewable biomass resources. In this respect, zeolite catalysts may help to develop a new generation of bio-fuel and chemical processes. In the new bio-paradigm not only acid but also basic materials will have an important and dominant role. Just to give some examples, basic zeolites based catalysts have been proposed for transesterification of triglyceride esters of fatty acids to biodiesel, for disrupting the lignin polymer by base catalyzed depolymerisation and for one pot lignin liquefaction by hydrogenation. (orig.)

Promotion effect of H2 on ethanol oxidation and NOx reduction with ethanol over Ag/Al2O3 catalyst.

Science.gov (United States)

Yu, Yunbo; Li, Yi; Zhang, Xiuli; Deng, Hua; He, Hong; Li, Yuyang

2015-01-06

The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol-SCR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol-SCR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing -NCO species again, leading to enhancement of ethanol-SCR over Ag/Al2O3 by H2. Using VUV-PIMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC-SCR over Ag/Al2O3.

Fischer-Tropsch Synthesis over Iron Manganese Catalysts: Effect of Preparation and Operating Conditions on Catalyst Performance

Directory of Open Access Journals (Sweden)

Ali A. Mirzaei

2009-01-01

molar basis which is the most active catalyst for the conversion of synthesis gas to light olefins. The effects of different promoters and supports with loading of optimum support on the catalytic performance of catalysts are also studied. It was found that the catalyst containing 50%Fe/50%Mn/5 wt.%Al2O3 is an optimum-modified catalyst. The catalytic performance of optimal catalyst has been studied in operation conditions such as a range of reaction temperatures, H2/CO molar feed ratios and a range of total pressures. Characterization of both precursors and calcined catalysts is carried out by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, BET specific surface area and thermal analysis methods such as TGA and DSC.

Evaluation of an olefin metathesis pre-catalyst with a bulky and electron-rich N-heterocyclic carbene

KAUST Repository

Manzini, Simone

2015-03-01

The commercially-available metathesis pre-catalyst M23 has been evaluated alongside new complex [RuCl2((3-phenyl)indenylidene)(PPh3)(SIPrOMe)] (1), which bears a para-methoxy-substituted N-heterocyclic carbene ligand. Several model metathesis reactions could be conducted using only parts-per-million levels of ruthenium catalyst. The effects of the different NHC ligands on reactivity have been explored.

Evaluation of an olefin metathesis pre-catalyst with a bulky and electron-rich N-heterocyclic carbene

KAUST Repository

Manzini, Simone; Urbina Blanco, Cé sar A.; Nelson, David J.; Poater, Albert; Lebl, Tomas; Meiries, Sé bastien; Slawin, Alexandra M.Z.; Falivene, Laura; Cavallo, Luigi; Nolan, Steven P.

2015-01-01

The commercially-available metathesis pre-catalyst M23 has been evaluated alongside new complex [RuCl2((3-phenyl)indenylidene)(PPh3)(SIPrOMe)] (1), which bears a para-methoxy-substituted N-heterocyclic carbene ligand. Several model metathesis reactions could be conducted using only parts-per-million levels of ruthenium catalyst. The effects of the different NHC ligands on reactivity have been explored.

Deactivation and regeneration of refinery catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

1979-08-01

A discussion covers the mechanisms of catalyst aging, poisoning, coke deposition, and metals deposition; feedstock pretreatment to extend catalyst life; the effects of operating conditions; the effects of catalyst composition and structure on its stability; nonchemical deactivation processes; and methods of catalyst regeneration, including coke burn-off and solvent extraction.

Engineering New Catalysts for In-Process Elimination of Tars

Energy Technology Data Exchange (ETDEWEB)

Felix, Larry G. [Gas Technology Inst., Des Plaines, IL (United States)

2012-09-30

and integrated (bulk) catalysts via a glass-ceramic processing route which were shown to exhibit excellent catalytic activity and superior resistance to attrition deactivation. With the discovery of these active, robust, glass-based catalysts, and with the permission of the project officer, the investigation of waste-based materials as originally proposed for Task 3 and pilot-scale testing proposed in Task 5 were deferred indefinitely in favor of further investigation of the glass-ceramic based catalyst materials. This choice was justified in part because during FY 2006 and through FY 2007, funding restrictions imposed by congressional budget choices significantly reduced funding for DOE biomass-related projects. Funding for this project was limited to what had been authorized which slowed the pace of project work at GTI so that our project partners could continue in their work. Thereafter, project work was allowed to resume and with restored funding, the project continued and concentrated on the development and testing of glass-ceramic catalysts in bulk or supported formats. Work concluded with a final development devoted to increasing the surface area of glass-ceramic catalysts in the form of microspheres. Following that development, project reporting was completed and the project was concluded.

Magnetic properties of iron-based catalysts activated by various CO{sub 2} concentrations

Energy Technology Data Exchange (ETDEWEB)

Lim, Jung Tae; Kim, Chul Sung [Kookmin University, Seoul (Korea, Republic of); Chun, Dong Hyun; Park, Ji Chan [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2014-12-15

Fresh catalyst samples of 100Fe/5.26Cu/4.76K/18.2SiO{sub 2} in part per weight were synthesized by using a combination of a co-precipitation technique and spray-drying method and were activated in situ by using syngas (H{sub 2}/CO/xCO{sub 2}) with different amounts of CO{sub 2} (x = 0.0, 0.5, 1.0, and 2.0). All activated catalyst samples showed similar XRD patterns, a combination of ferrihydrite, magnetite, χ-carbide, and ε'-carbide, regardless of the CO{sub 2} contents. From the Moessbauer spectra, we also observed a combination of ferrihydrite, magnetite, χ-carbide, and ε'-carbide in all activated catalyst samples. The main compound of the activated catalyst sample activated by using CO{sub 2}-free syngas (H{sub 2}/CO) was magnetic χ-carbide, and the main compound changed from χ-carbide to ferrihydrite with increasing CO{sub 2} concentration, confirmed by both, Moessbauer spectra and XRD pattern.

Autothermal reforming catalyst having perovskite structure

Science.gov (United States)

Krumpel, Michael [Naperville, IL; Liu, Di-Jia [Naperville, IL

2009-03-24

The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

Isotope exchange in oxide-containing catalyst

Science.gov (United States)

Brown, Kenneth G. (Inventor); Upchurch, Billy T. (Inventor); Hess, Robert V. (Inventor); Miller, Irvin M. (Inventor); Schryer, David R. (Inventor); Sidney, Barry D. (Inventor); Wood, George M. (Inventor); Hoyt, Ronald F. (Inventor)

1989-01-01

A method of exchanging rare-isotope oxygen for common-isotope oxygen in the top several layers of an oxide-containing catalyst is disclosed. A sample of an oxide-containing catalyst is exposed to a flowing stream of reducing gas in an inert carrier gas at a temperature suitable for the removal of the reactive common-isotope oxygen atoms from the surface layer or layers of the catalyst without damaging the catalyst structure. The reduction temperature must be higher than any at which the catalyst will subsequently operate. Sufficient reducing gas is used to allow removal of all the reactive common-isotope oxygen atoms in the top several layers of the catalyst. The catalyst is then reoxidized with the desired rare-isotope oxygen in sufficient quantity to replace all of the common-isotope oxygen that was removed.

Bifunctional cobalt F-T catalysts

Energy Technology Data Exchange (ETDEWEB)

Miller, J.G.; Coughlin, P.K.; Yang, C.L.; Rabo, J.A.

1986-03-01

Results on the catalytic screening of Fischer-Tropsch catalysts containing shape selective components are reported. Catalysts consist of promoted cobalt intimately contacted with Union Carbide molecular sieves and were tested using a Berty type internally recycled reactor. Methods of preparation, promoters and shape selective components were varied and aimed at improving catalyst performance. Catalysts were developed demonstrating high C/sub 5/ + yields with high olefin content and low methane production while maintaining stability under both low and high H/sub 2/:CO ratio conditions.

Estimation of Kinetic Parameters in an Automotive SCR Catalyst Model

DEFF Research Database (Denmark)

Åberg, Andreas; Widd, Anders; Abildskov, Jens

2016-01-01

be used directly for accurate full-scale transient simulations. The model was validated against full-scale data with an engine following the European Transient Cycle. The validation showed that the predictive capability for nitrogen oxides (NOx) was satisfactory. After re-estimation of the adsorption...... and desorption parameters with full-scale transient data, the fit for both NOx and NH3-slip was satisfactory....

Oxygen-reducing catalyst layer

Science.gov (United States)

O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

2011-03-22

An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

Recovery of platinum-group metals (PGMS from spent automotive catalysts: Part II: Automotive catalysts: Structures and principle of operation

Directory of Open Access Journals (Sweden)

Dimitrijević Mile D.

2015-01-01

Full Text Available Catalytic converters are incorporated into motor vehicle emission systems (passenger cars, trucks and other motor vehicles, as well as civil and agricultural machines, as of lately to reduce air pollution as well as to meet the emission standards. Their purpose is to convert toxic emissions generated by combustion of liquid fossil fuels into less harmful products. In catalytic converters, rhodium is used for the reduction of gasses, whereas platinum and palladium are used for the oxidation of gasses. This paper presents the structure and operating principle of automotive catalysts in view of the fact that cars are the most prevalent motor vehicles worldwide and due to the fact that the production of cars with gasoline and diesel engines will dominate until at least 2020.

Decision-making and addiction (part II): myopia for the future or hypersensitivity to reward?

Science.gov (United States)

Bechara, Antoine; Dolan, Sara; Hindes, Andrea

2002-01-01

On a decision-making instrument known as the "gambling task" (GT), a subgroup of substance dependent individuals (SDI) opted for choices that yield high immediate gains in spite of higher future losses. This resembles the behavior of patients with ventromedial (VM) prefrontal cortex lesions. In this study, we addressed the possibility that hypersensitivity to reward may account for the "myopia" for the future in this subgroup of SDI. We used a variant version of the GT, in which the good decks yielded high immediate punishment but higher delayed reward. The bad decks yielded low immediate punishment and lower delayed reward. We measured the skin conductance response (SCR) of subjects after receiving reward (reward SCR) and during their pondering from which deck to choose (anticipatory SCR). A subgroup of SDI who was not impaired on the original GT performed normally on the variant GT. The subgroup of SDI who was impaired on the original GT showed two levels of performance on the variant GT. One subgroup (36% of the sample) performed poorly on the variant GT, and showed similar behavioral and physiological impairments to VM patients. The other subgroup of SDI (64% of the sample) performed normally on the variant task, but had abnormally large physiological responses to reward, i.e. large SCR after receiving reward (reward SCR) and large SCR in anticipation of outcomes that yield large reward. Thus, the combined cognitive and physiological approach of assessing decision-making characterizes three sub-populations of SDI. One sub-population is without impairments that can be detected by any measure of the GT paradigm. Another sub-population is similar to VM patients in that they are insensitive to the future, both positive and negative. A third sub-population is hypersensitive to reward, so that the presence or the prospect of receiving, reward dominates their behavior.

Hydroprocessing Catalysts. Utilization and Regeneration Schemes Catalyseurs d'hydrotraitement. Schémas d'utilisation et de régénération

OpenAIRE

Furimsky E.

2006-01-01

The catalyst reactor inventory represents an important part of the cost of hydroprocessing operation. The selection of a suitable catalyst and reactor is influenced by feedstock properties. Processes ensuring an uninterrupted operation during catalyst addition and withdrawal are preferred for processing high asphaltene and metal content feedstocks. The spent catalyst can be regenerated and returned to the operation if the extent of its deactivation is not high. The regeneration may be perform...

Preparation and characterization of multi-walled carbon nanotube (MWCNTs)-supported Pt-Ru catalyst for methanol electrooxidation

Energy Technology Data Exchange (ETDEWEB)

Yang Chunwei [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: cw.yang@hit.edu.cn; Wang Dianlong; Hu Xinguo; Dai Changsong [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhang Liang [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2008-01-10

Multi-walled carbon nanotubes (MWCNTs) as a support of PtRu catalyst nanocomposites were prepared by colloid method in this work. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) all indicate that ultrasonic treatment can effectively functionalize MWCNTs, endowing them with groups that can act as nucleation sites which can favor well-dispersed deposition of PtRu clusters on their surface. The PtRu/MWCNTs catalysts have a high and homogeneous dispersion of spherical PtRu metal particles with a narrow particle-size distribution. From XPS tests, in PtRu/MWCNTs catalysts Ru can weaken the out-shell electrons of Pt because a part of Ru form alloy with Pt. The remnant Ru exists in oxidation and provides abundant oxygen to nearby Pt, as accelerated desorption and oxidation of intermediate products of methanol oxidation at surface of Pt. By a series of electrochemistry measurements, the PtRu/MWCNTs catalysts display significantly higher performance than the PtRu/XC-72 catalysts. Finally, schematic procedures for the oxidation of MWCNTs and synthesis of PtRu/MWCNTs catalysts were given.

Preparation and characterization of multi-walled carbon nanotube (MWCNTs)-supported Pt-Ru catalyst for methanol electrooxidation

International Nuclear Information System (INIS)

Yang Chunwei; Wang Dianlong; Hu Xinguo; Dai Changsong; Zhang Liang

2008-01-01

Multi-walled carbon nanotubes (MWCNTs) as a support of PtRu catalyst nanocomposites were prepared by colloid method in this work. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) all indicate that ultrasonic treatment can effectively functionalize MWCNTs, endowing them with groups that can act as nucleation sites which can favor well-dispersed deposition of PtRu clusters on their surface. The PtRu/MWCNTs catalysts have a high and homogeneous dispersion of spherical PtRu metal particles with a narrow particle-size distribution. From XPS tests, in PtRu/MWCNTs catalysts Ru can weaken the out-shell electrons of Pt because a part of Ru form alloy with Pt. The remnant Ru exists in oxidation and provides abundant oxygen to nearby Pt, as accelerated desorption and oxidation of intermediate products of methanol oxidation at surface of Pt. By a series of electrochemistry measurements, the PtRu/MWCNTs catalysts display significantly higher performance than the PtRu/XC-72 catalysts. Finally, schematic procedures for the oxidation of MWCNTs and synthesis of PtRu/MWCNTs catalysts were given

Metal catalysts fight back

OpenAIRE

George Marsh

1998-01-01

In recent years organometallic catalysts, especially metallocenes, have been a major focus of attention in terms of polymerisation chemistry. But the news earlier this year of a family of iron-based catalysts able to rival the effectiveness of both conventional and metallocene catalysts in the polymerisation of ethylene has excited the plastics industry. Because of the impact of this discovery and its potential as a route to lower-priced commodity plastics in the future, it may be useful at t...

Productions of palm oil bio diesel whit heterogeneous basic catalysts compared to conventional homogeneous catalysts

International Nuclear Information System (INIS)

Rios, Luis A; Franco C, Alexander; Zuleta S, Ernesto

2009-01-01

The conventional process to produce biodiesel involves the presence of homogeneous basic catalysts. However, these catalysts have disadvantages associated to the need of purification steps, which increase the cost of the final product and generate pollution problems caused by the effluents. This paper compares different homogeneous and heterogeneous catalysts for the biodiesel production from palm oil. For this, heterogeneous catalysts supported on alumina were prepared and characterized by nitrogen adsorption, scanning electron microscopy, energy dispersive X ray spectroscopy and X ray diffraction. Transesterification of palm oil with methanol was accomplished at 60 celsius degrade and one hour, varying methanol/oil ratio, the type of catalyst and its concentration. Yields of the reaction and purity of the so obtained biodiesel were evaluated. Comparing the catalysts performance, based on the amount, was found that sodium methoxide (CH 3 ONa) and potassium carbonate supported on alumina (K 2 CO 3 /Al 2 O 3 ) were the catalysts that give the higher purity of biodiesel (96.8 and 95.85% respectively). When was determined the active site quality, by dividing the performance by each mole of active sites, it was found that calcined Na 2 SO 4 /Al 2 O 3 has the most active sites.

Novel metalloporphyrin catalysts for the oxidation of hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Showalter, M.C.; Nenoff, T.M.; Shelnutt, J.A.

1996-11-01

Work was done for developing biomimetic oxidation catalysts. Two classes of metalloporphyrin catalysts were studied. The first class of catalysts studied were a novel series of highly substituted metalloporphyrins, the fluorinated iron dodecaphenylporphyrins. These homogeneous metalloporphyrin catalysts were screened for activity as catalysts in the oxidation of hydrocarbons by dioxygen. Results are discussed with respect to catalyst structural features. The second type of catalysts studied were heterogeneous catalysts consisting of metalloporphyrins applied to inorganic supports. Preliminary catalytic testing results with these materials are presented.

Optimal catalyst curves: Connecting density functional theory calculations with industrial reactor design and catalyst selection

DEFF Research Database (Denmark)

Jacobsen, C.J.H.; Dahl, Søren; Boisen, A.

2002-01-01

For ammonia synthesis catalysts a volcano-type relationship has been found experimentally. We demonstrate that by combining density functional theory calculations with a microkinetic model the position of the maximum of the volcano curve is sensitive to the reaction conditions. The catalytic...... ammonia synthesis activity, to a first approximation, is a function only of the binding energy of nitrogen to the catalyst. Therefore, it is possible to evaluate which nitrogen binding energy is optimal under given reaction conditions. This leads to the concept of optimal catalyst curves, which illustrate...... the nitrogen binding energies of the optimal catalysts at different temperatures, pressures, and synthesis gas compositions. Using this concept together with the ability to prepare catalysts with desired binding energies it is possible to optimize the ammonia process. In this way a link between first...

European workshop on spent catalysts. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

In 1999 and 2002 two well attended workshops on recycling, regeneration, reuse and disposal of spent catalysts took place in Frankfurt. This series has been continued in Berlin. The workshop was organized in collaboration with DGMK, the German Society for Petroleum and Coal Science and Technology. Contributions were in the following areas of catalyst deactivation: recycling of spent catalysts in chemical and petrochemical industry, recycling of precious metal catalysts and heterogenous base metal catalysts, legal aspects of transboundary movements, catalyst regeneration, quality control, slurry catalysts, commercial reactivation of hydrotreating catalysts. (uke)

CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

DEFF Research Database (Denmark)

Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil

2007-01-01

with compositions 25Fe75Ni and 50Fe50Ni showed significantly better activity and in some cases also a higher selectivity to methane compared with the traditional monometallic Ni and Fe catalysts. A catalyst with composition 25Fe75Ni was found to be the most active in CO hydrogenation for the MgAl2O4 support at low...... metal loadings. At high metal concentrations, the maximum for the methanation activity was found for catalysts with composition 50Ni50Fe both on the MgAl2O4 and Al2O3 supports. This difference can be attributed to a higher reducibility of the constituting metals with increasing metal concentration......DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. Here...

Electron Tomography Reveals the Active Phase–Support Interaction in Sulfidic Hydroprocessing Catalysts

NARCIS (Netherlands)

Eijsbouts, Sonja; Li, Xuang; Juan-Alcaniz, Jana; van den Oetelaar, Leon C A; Bergwerff, Jaap; Loos, Joachim; Carlsson, Anna; Vogt, E.T.C.

2017-01-01

Conventional two-dimensional (2D) transmission electron microscopy of sulfidic hydroprocessing catalysts can be deceiving and give the impression that parts of the support are overloaded with active phase. High-angle annular dark field scanning transmission electron microscopy tomography reveals

Tracing the origin of S-Cr. novac 'money'

Directory of Open Access Journals (Sweden)

Vlajić-Popović Jasna

2010-01-01

Full Text Available The paper points at the imprecision of the hitherto prevailing etymology of S-Cr. novac ‘money’ as an univerbization departing from the adjective nov ‘new’, through an undated and undefined *novi penez /dinar. After a review of previous interpretations and the corpus of lexicographic attestations of the noun novac, the areal distribution of its earliest Croatian and Serbian attestations (from the 16th and 17th centuries respectively, as well as the 18th century Sln. novz ‘nummus ungaricus’ is taken as an indication of Hungarian source of influence. Hence the nomination impulse is found in Latin, the official language in medieval Hungary, where in some 15th century legal documents from the Zagreb court the syntagm novorum denariorum (Gen. pl. occurs simultaneously and synonymously with the nominalized adj. novos (Acc. pl.. The semantic borrowing into local Slavic novac /novec ‘new coin (initially 1/100 of a dukat’, evolves into ‘coin of small value’ and eventually, through a negative phrase nemati ni novca ‘to be broke’ (lit.: ‘to have not a single penny’ into ‘money (in general; wealth’. In both meanings it entered the vernaculars of the entire Štokavian territory (some time during the 18th century, which is reflected in folk poetry, paremiology, etc. The term novac has suppressed the previously widespread Slavic term penezi /pjenezi /pinezi and entered a co-existence with the Turcism para f. ‘coin’, pare pl. ‘money’ which lasts into this day. Since the nomination from the adj. nov is unique among standardly known terms for money (cf. Buck s.v., a precious onomasiological parallelism to this formation is discovered in Serb. dial. novica ‘a Turkish 20 gr coin’, ‘a fake coin’.

Epoxidation catalyst and process

Science.gov (United States)

Linic, Suljo; Christopher, Phillip

2010-10-26

Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

Enhanced activity of Pt/CNTs anode catalyst for direct methanol fuel cells using Ni2P as co-catalyst

Science.gov (United States)

Li, Xiang; Luo, Lanping; Peng, Feng; Wang, Hongjuan; Yu, Hao

2018-03-01

The direct methanol fuel cell is a promising energy conversion device because of the utilization of the state-of-the-art platinum (Pt) anode catalyst. In this work, novel Pt/Ni2P/CNTs catalysts were prepared by the H2 reduction method. It was found that the activity and stability of Pt for methanol oxidation reaction (MOR) could be significantly enhanced while using nickel phosphide (Ni2P) nanoparticles as co-catalyst. X-ray photoelectron spectroscopy revealed that the existence of Ni2P affected the particle size and electronic distribution of Pt obviously. Pt/CNTs catalyst, Pt/Ni2P/CNTs catalysts with different Ni2P amount were synthesized, among which Pt/6%Ni2P/CNTs catalyst exhibited the best MOR activity of 1400 mAmg-1Pt, which was almost 2.5 times of the commercial Pt/C-JM catalyst. Moreover, compared to other Pt-based catalysts, this novel Pt/Ni2P/CNTs catalyst also exhibited higher onset current density and better steady current density. The result of this work may provide positive guidance to the research on high efficiency and stability of Pt-based catalyst for direct methanol fuel cells.

Combustion, performance, and selective catalytic reduction of NOx for a diesel engine operated with combined tri fuel (H_2, CH_4, and conventional diesel)

International Nuclear Information System (INIS)

Abu-Jrai, Ahmad M.; Al-Muhtaseb, Ala'a H.; Hasan, Ahmad O.

2017-01-01

In this study, the effect of tri fuel (ULSD, H_2, and CH_4) operation under real exhaust gas conditions with different gaseous fuel compositions on the combustion characteristics, engine emissions, and selective catalytic reduction (SCR) after treatment was examined at low, medium, and high engine loads. Pt/Al_2O_3-SCR reactor was used and operated at different exhaust gas temperatures. Results revealed that at low load, the two gaseous fuels (H_2 and CH_4) have the same trend on combustion proccess, where both reduce the in-cylinder pressure and rate of heat release. At the high engine load there was a considerable influence appeared as an increase of the premixed combustion phase and a significant decrease of the total combustion duration. In terms of emissions, it was observed that at high engine load, fuels with high CH_4 content tend to reduce NOx formation, whereas, fuels with high H_2 content tend to reduce PM formation, moreover, combustion of tri fuel with 50:50 fuel mixture resulted in lower BSFC compared to the other ratios and hence, the best engine efficiency. The hydrocarbon-SCR catalyst has shown satisfactory performance in NOx reduction under real diesel exhaust gas in a temperature window of 180–280 °C for all engine loads. - Highlights: • Effect of tri fuel (ULSD, H_2, CH_4) on combustion and engine emissions was examined. • Fuel with high CH_4 content (H50-M50 and H25-M75) tend to reduce NOx formation. • Fuel with high H_2 content (H75-M25 and H50-M50) tend to reduce PM formation. • Increasing the percentage of H_2 in the feed gas improved the NO_x reduction. • The hydrocarbon-SCR catalyst has shown satisfactory performance in NO_x reduction.

Rare earth metals for automotive exhaust catalysts

International Nuclear Information System (INIS)

Shinjoh, Hirohumi

2006-01-01

The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

Alkaline Ionic Liquid Modified Pd/C Catalyst as an Efficient Catalyst for Oxidation of 5-Hydroxymethylfurfural

Directory of Open Access Journals (Sweden)

Zou Bin

2018-01-01

Full Text Available Conversion of HMF into FDCA was carried out by a simple and green process based on alkaline ionic liquid (IL modified Pd/C catalyst (Pd/C-OH−. Alkaline ionic liquids were chosen to optimize Pd/C catalyst for special hydrophilicity and hydrophobicity, redox stability, and unique dissolving abilities for polar compounds. The Pd/C-OH− catalyst was successfully prepared and characterized by SEM, XRD, TG, FT-IR, and CO2-TPD technologies. Loading of alkaline ionic liquid on the surface of Pd/C was 2.54 mmol·g−1. The catalyst showed excellent catalytic activity in the HMF oxidation after optimization of reaction temperature, reaction time, catalyst amount, and solvent. Supported alkaline ionic liquid (IL could be a substitute and promotion for homogeneous base (NaOH. Under optimal reaction conditions, high HMF conversion of 100% and FDCA yield of 82.39% were achieved over Pd/C-OH− catalyst in water at 373 K for 24 h.

Carbonaceous deposits on naptha reforming catalysts

International Nuclear Information System (INIS)

Redwan, D.S.

1999-01-01

Carbonaceous deposits on naphtha reforming catalysts play a decisive role in limiting process performance. The deposits negatively after catalyst activity, selectivity and the production cycle of a semi regenerative reformer. The magnitude of negative effect of those deposits is directly proportional to their amounts and complexity. Investigations on used reforming catalysts samples reveal that the amount and type (complexity of the chemical nature) of carbonaceous deposits are directly proportional to the catalysts life on stream and the severity of operating conditions. In addition, the combustibility behavior of carbonaceous deposits on the catalyst samples taken from different reformers are found to be different. Optimal carbon removal, for in situ catalyst regeneration, requires the specific conditions be developed, based on the results of well designed and properly performed investigations of the amount and type of carbonaceous deposits. (author)

Reducible oxide based catalysts

Science.gov (United States)

Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

2010-04-06

A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

Increasing the lifetime of fuel cell catalysts

NARCIS (Netherlands)

Latsuzbaia, R.

2015-01-01

In this thesis, I discuss a novel idea of fuel cell catalyst regeneration to increase lifetime of the PEM fuel cell electrode/catalyst operation and, therefore, reduce the catalyst costs. As many of the catalyst degradation mechanisms are difficult to avoid, the regeneration is alternative option to

Hydroprocessing using regenerated spent heavy hydrocarbon catalyst

International Nuclear Information System (INIS)

Clark, F.T.; Hensley, A.L. Jr.

1992-01-01

This patent describes a process for hydroprocessing a hydrocarbon feedstock. It comprises: contacting the feedstock with hydrogen under hydroprocessing conditions with a hydroprocessing catalyst wherein the hydroprocessing catalyst contains a total contaminant metals build-up of greater than about 4 wt. % nickel plus vanadium, a hydrogenation component selected from the group consisting of Group VIB metals and Group VIII metals and is regenerated spent hydroprocessing catalyst regenerated by a process comprising the steps: partially decoking the spent catalyst in an initial coke-burning step; impregnating the partially decoked catalyst with a Group IIA metal-containing impregnation solution; and decoking the impregnated catalyst in a final coke-burning step wherein the impregnated catalyst is contacted with an oxygen-containing gas at a temperature of about 600 degrees F to about 1400 degrees F

Techniques for measuring ammonia in fly ash, mortar, and concrete

Energy Technology Data Exchange (ETDEWEB)

Rathbone, R.F. [Kentucky Univ., Lexington, KY (United States). Center for Applied Energy Reseach; Majors, R.K. [Boral Material Technologies, Inc., San Antonio, TX (United States). Engineered Materials

2003-12-01

The presence of ammonia in fly ash that is to be used in mortar and concrete is of increasing concern in the U.S., mainly due to the installation of selective catalytic reduction (SCR) DeNOx systems. When the SCR catalyst is new, contamination of the fly ash with ammonia is generally not a concern. However, as the catalyst in the SCR ages and becomes less efficient, the ammonia slip increases and results in a greater amount of ammonium salt being precipitated on the fly ash. The increase in ammonia concentration is compounded by variability that can occur on a day-to-day basis. When marketing ammonia-laden fly ash for use in mortar and concrete it is imperative that the concentration of ammonia is known. However, there currently is no widely accepted or ''standard'' method for ammonia measurement in fly ash. This paper describes two methods that have been developed and used by the University of Kentucky Center for Applied Energy Research and Boral Material Technologies, Inc. One of the methods uses gas detection tubes and can provide an accurate determination within five to ten minutes. Thus it is suitable as a rapid field technique. The other method employs a gas-sensing electrode and requires a longer period of time to complete the measurement. However, this second method can also be used to determine the quantity of ammonia in fresh mortar and concrete. (orig.)

Extended Catalyst Longevity Via Supercritical Isobutane Regeneration of a Partially Deactivated USY Alkylation Catalyst

Energy Technology Data Exchange (ETDEWEB)

Daniel M. Ginosar; David N. Thompson; Kyle C. Burch; David J. Zalewski

2005-05-01

Off-line, in situ activity recovery of a partially deactivated USY zeolite catalyst used for isobutane/butene alkylation was examined in a continuous-flow reaction system employing supercritical isobutane. Catalyst samples were deactivated in a controlled manner by running them to either to a fixed butene conversion level of 95% or a fixed time on stream of three hours, and then exposing the catalyst to supercritical isobutane to restore activity. Activity recovery was determined by comparing alkylation activity before and after the regeneration step. Both single and multiple regenerations were performed. Use of a 95% butene conversion level criterion to terminate the reaction step afforded 86% activity recovery for a single regeneration and provided nine sequential reaction steps for the multiple regeneration studies. Employing a fixed 3 h time on stream criterion resulted in nearly complete activity recovery for a single regeneration, and 24 reaction steps were demonstrated in sequence for the multiple regeneration process, producing only minor product yield declines per step. This resulted in a 12-fold increase in catalyst longevity versus unregenerated catalyst.

The development of isomerization catalysts for production of high-octane products

Energy Technology Data Exchange (ETDEWEB)

Pedrosa, A.M. Garrido; Melo, D.M.A.; Araujo, A.S. [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil). Dept. de Quimica; Souza, M.J.B.; Silva, A.O.S. [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil). Dept. de Engenharia Quimica

2004-07-01

In current petroleum industry, paraffins larger than C5 are used for catalytic reform. The catalytic reform is one of the most important processes for petroleum refine in reason of all reactions they drive to production of high-octane products. Reformate has high-octane products, but they contain 60% aromatics. Isomerization of C5- C7 can improve the octane number. The octane number of n-heptane is zero and increases after isomerization. For tri branched C7, the octane number reaches 113, which is higher than that of benzene. So, isomerization of C5-C7 is suggested to be a reasonable way to replace or partly replace the catalytic reforming process. It can decrease aromatics content with enhancement of octane number. Liquid acid catalysts were widely used in chemical industry in past decades. However, they face strong environmental challenges. The heavy corrosion of the reactor system is one of the main problems. Thus, solid acid catalysts are investigated for the isomerization reactions. The aim of this work is to develop a catalysts for the production of reformate products. Isomerization is catalyzed by metal-acid bifunctional catalysts. The metal components aid in hydrogenation, while the support, such as, zirconium, clays or zeolites, is the acidic component. (author)

The Stability of Supported Gold Catalysts

NARCIS (Netherlands)

Masoud, Nazila

2018-01-01

Gold has supreme cultural and financial value and, in form of nanoparticles smaller than 10 nm, is a unique catalyst for different industrially relevant reactions. Intriguing properties of the gold catalysts have spurred demand in the chemical industry for Au catalysts, the application of which

Coupling catalytic hydrolysis and oxidation on Mn/TiO2-Al2O3 for HCN removal

Science.gov (United States)

Wang, Langlang; Wang, Xueqian; Cheng, Jinhuan; Ning, Ping; Lin, Yilong

2018-05-01

The manganese-modified titania-alumina (Mn/TiO2-Al2O3) catalyst synthesized by sol-gol method was used to remove hydrogen cyanide (HCN) from simulated flue gas. Further, effects of the mass ratios of Ti/Al, Mn loading, calcination temperature, and relative humidity on HCN conversion efficiency and catalytic activity were systematically investigated. The results indicated that the Mn/TiO2-Al2O3 catalyst exhibited significantly enhanced HCN removal efficiency, and the maximum yield of N2 increased to 68.02% without the participation of water vapor. When water vapor was added into the flue gas, the yield of N2 decreased and the formation of NOx was also inhibited. The XRD and XPS results indicated that Mn was mainly present in the form of Mn2+, Mn3+, and Mn4+ on the surface of catalyst and chemisorbed oxygen played a major role in the HCN catalytic oxidation process. The results of DSC-TGA analysis and H2-TPR indicated that the catalyst also exhibited a good thermal and chemical stability. NH3-TPD and CO2-TPD indicated that the surface of the catalyst mainly contained acidic sites. During the reaction, part of NH3 was adsorbed by Brönsted and Lewis acid sites. NH3 adsorbed on Lewis acid sites participated in NH3-SCR, which reduced the amount of NOx produced and resulted in a high N2 yield.

Nitrogen oxides storage catalysts containing cobalt

Science.gov (United States)

Lauterbach, Jochen; Snively, Christopher M.; Vijay, Rohit; Hendershot, Reed; Feist, Ben

2010-10-12

Nitrogen oxides (NO.sub.x) storage catalysts comprising cobalt and barium with a lean NO.sub.x storage ratio of 1.3 or greater. The NO.sub.x storage catalysts can be used to reduce NO.sub.x emissions from diesel or gas combustion engines by contacting the catalysts with the exhaust gas from the engines. The NO.sub.x storage catalysts can be one of the active components of a catalytic converter, which is used to treat exhaust gas from such engines.

FCC catalyst technologies expand limits of process capability

International Nuclear Information System (INIS)

Leiby, S.

1992-01-01

This paper reports that over the past 30 or so years, many improvements in fluid catalytic cracking (FCC) operation have been achieved as the result of innovations in catalyst formulation. During the 1990s, new environmental regulations on issues such as reformulated gasoline will place new demands on both the refining industry and catalyst suppliers. An overview of cracking catalyst technology therefore seems in order. Today, high-technology innovations by catalyst manufacturers are rapid, but profit margins are slim. Catalyst formulations are shrouded in secrecy and probably depend almost as much on art as on science. Special formulations for specific cracking applications get the greatest emphasis today. To illustrate this point, OGJ's Worldwide Catalyst Report lists over 200 FCC catalyst designations. Catalysts containing components to enhance gasoline octane now account for about 70% of total U.S. FCC catalyst usage

Bio-inspired co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

DEFF Research Database (Denmark)

Hou, Yidong; Abrams, Billie; Vesborg, Peter Christian Kjærgaard

2011-01-01

The production of fuels directly or indirectly from sunlight represents one of the major challenges to the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and while platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen...... at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10%. The experimental observations are supported by DFT calculations of the Mo3S4 cluster adsorbed on the hydrogen-terminated silicon surface providing insights...... deposited on various supports. It will be demonstrated how this overpotential can be eliminated by depositing the same type of hydrogen evolution catalyst on p-type Si which can harvest the red part of the solar spectrum. Such a system could constitute the cathode part of a tandem dream device where the red...

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

Energy Technology Data Exchange (ETDEWEB)

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

2006-08-01

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

Catalyst for Ammonia Oxidation

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

Studies on the promotion of nickel—alumina coprecipitated catalysts: III. Cerium oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Slaa, J.C.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

Three series of cerium-promoted nickel—alumina catalysts with different nickel-to-aluminium ratios each containing different amounts of cerium have been prepared and characterized. The calcination and reduction behaviour were found not to be altered by the presence of cerium. Part of the promoter

DEVELOPMENT OF PRECIPITATED IRON FISCHER-TROPSCH CATALYSTS

International Nuclear Information System (INIS)

Bukur, Dragomir B.; Lang, X.; Chokkaram, S.; Nowicki, L.; Wei, G.; Ding, Y.; Reddy, B.; Xiao, S.

1999-01-01

Despite the current worldwide oil glut, the US will ultimately require large-scale production of liquid (transportation) fuels from coal. Slurry phase Fischer-Tropsch (F-T) technology, with its versatile product slate, may be expected to play a major role in production of transportation fuels via indirect coal liquefaction. Some of the F-T catalysts synthesized and tested at Texas A and M University under DOE Contract No. DE-AC22-89PC89868 were more active than any other known catalysts developed for maximizing production of high molecular weight hydrocarbons (waxes). The objectives of the present contract were to demonstrate repeatability of catalyst performance and reproducibility of preparation procedures of two of these catalysts on a laboratory scale. Improvements in the catalyst performance were attempted through the use of: (a) higher reaction pressure and gas space velocity to maximize the reactor productivity; (b) modifications in catalyst preparation steps; and (c) different pretreatment procedures. Repeatability of catalyst performance and reproducibility of catalyst synthesis procedure have been successfully demonstrated in stirred tank slurry reactor tests. Reactor space-time-yield was increased up to 48% by increasing reaction pressure from 1.48 MPa to 2.17 MPa, while maintaining the gas contact time and synthesis gas conversion at a constant value. Use of calcination temperatures above 300 C, additional CaO promoter, and/or potassium silicate as the source of potassium promoter, instead of potassium bicarbonate, did not result in improved catalyst performance. By using different catalyst activation procedures they were able to increase substantially the catalyst activity, while maintaining low methane and gaseous hydrocarbon selectivities. Catalyst productivity in runs SA-0946 and SA-2186 was 0.71 and 0.86 gHC/g-Fe/h, respectively, and this represents 45-75% improvement in productivity relative to that achieved in Rheinpreussen's demonstration plant

Catalyst systems and uses thereof

Science.gov (United States)

Ozkan, Umit S [Worthington, OH; Holmgreen, Erik M [Columbus, OH; Yung, Matthew M [Columbus, OH

2012-07-24

A method of carbon monoxide (CO) removal comprises providing an oxidation catalyst comprising cobalt supported on an inorganic oxide. The method further comprises feeding a gaseous stream comprising CO, and oxygen (O.sub.2) to the catalyst system, and removing CO from the gaseous stream by oxidizing the CO to carbon dioxide (CO.sub.2) in the presence of the oxidation catalyst at a temperature between about 20 to about 200.degree. C.

Designing Multifunctionality into Single Phase and Multiphase Metal-Oxide-Selective Propylene Ammoxidation Catalysts

Directory of Open Access Journals (Sweden)

James F. Brazdil

2018-03-01

Full Text Available Multifunctionality is the hallmark of most modern commercial heterogeneous catalyst systems in use today, including those used for the selective ammoxidation of propylene to acrylonitrile. It is the quintessential principle underlying commercial catalyst design efforts since petrochemical process development is invariably driven by the need to reduce manufacturing costs. This is in large part achieved through new and improved catalysts that increase selectivity and productivity. In addition, the future feedstocks for chemical processes will be invariably more refractory than those currently in use (e.g., replacing alkenes with alkanes or using CO2, thus requiring a disparate combination of chemical functions in order to effect multiple chemical transformations with the fewest separate process steps. This review summarizes the key chemical phenomena behind achieving the successful integration of multiple functions into a mixed-metal-oxide-selective ammoxidation catalyst. An experiential and functional catalyst design model is presented that consists of one or both of the following components: (1 a mixed-metal-oxide–solid solution where the individual metal components serve separate and necessary functions in the reaction mechanism through their atomic level interaction in the context of a single crystallographic structure; (2 the required elemental components and their catalytic function existing in separate phases, where these phases are able to interact for the purposes of electron and lattice oxygen transfer through the formation of a structurally coherent interface (i.e., epitaxy between the separate crystal structures. Examples are provided from the literature and explained in the context of this catalyst design model. The extension of the model concepts to the design of heterogeneous catalysts in general is also discussed.

Highly Stable and Active Catalyst for Sabatier Reactions

Science.gov (United States)

Hu, Jianli; Brooks, Kriston P.

2012-01-01

Highly active Ru/TiO2 catalysts for Sabatier reaction have been developed. The catalysts have shown to be stable under repeated shutting down/startup conditions. When the Ru/TiO2 catalyst is coated on the engineered substrate Fe-CrAlY felt, activity enhancement is more than doubled when compared with an identically prepared engineered catalyst made from commercial Degussa catalyst. Also, bimetallic Ru-Rh/TiO2 catalysts show high activity at high throughput.

Advanced CIDI Emission Control System Development

Energy Technology Data Exchange (ETDEWEB)

Lambert, Christine

2006-05-31

Ford Motor Company, with ExxonMobil and FEV, participated in the Department of Energy's (DOE) Ultra-Clean Transportation Fuels Program with the goal to develop an innovative emission control system for light-duty diesel vehicles. The focus on diesel engine emissions was a direct result of the improved volumetric fuel economy (up to 50%) and lower CO2 emissions (up to 25%) over comparable gasoline engines shown in Europe. Selective Catalytic Reduction (SCR) with aqueous urea as the NOx reductant and a Catalyzed Diesel Particulate Filter (CDPF) were chosen as the primary emission control system components. The program expected to demonstrate more than 90% durable reduction in particulate matter (PM) and NOx emissions on a light-duty truck application, based on the FTP-75 drive cycle. Very low sulfur diesel fuel (<15 ppm-wt) enabled lower PM emissions, reduced fuel economy penalty due to the emission control system and improved long-term system durability. Significant progress was made toward a durable system to meet Tier 2 Bin 5 emission standards on a 6000 lbs light-duty truck. A 40% reduction in engine-out NOx emissions was achieved with a mid-size prototype diesel engine through engine recalibration and increased exhaust gas recirculation. Use of a rapid warm-up strategy and urea SCR provided over 90% further NOx reduction while the CDPF reduced tailpipe PM to gasoline vehicle levels. Development work was conducted to separately improve urea SCR and CDPF system durability, as well as improved oxidation catalyst function. Exhaust gas NOx and ammonia sensors were also developed further. While the final emission control system did not meet Tier 2 Bin 5 NOx after 120k mi of aging on the dynamometer, it did meet the standards for HC, NMOG, and PM, and an improved SCR catalyst was shown to have potential to meet the NOx standard, assuming the DOC durability could be improved further. Models of DOC and SCR function were developed to guide the study of several key

Active carbon catalyst for heavy oil upgrading

Energy Technology Data Exchange (ETDEWEB)

Fukuyama, Hidetsugu; Terai, Satoshi [Technology Research Center, Toyo Engineering Corporation, 1818 Azafujimi, Togo, Mobara-shi, Chiba 297-00017 (Japan); Uchida, Masayuki [Business Planning and Exploring Department, Overseas Business Development and Marketing Division, Toyo Engineering Corporation, 2-8-1 Akanehama, Narashino-shi, Chiba 275-0024 (Japan); Cano, Jose L.; Ancheyta, Jorge [Maya Crude Treatment Project, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico D.F. 07730 (Mexico)

2004-11-24

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought to play an important role for effective conversion of heavy hydrocarbon compounds into lighter fractions restricting carbon formation. The performance of the AC catalyst was examined by continuous hydrocracking by CSTR for the removal of such impurities as sulfur and heavy metals (nickel and vanadium), which are mostly concentrated in the asphaltenes. The AC catalyst was confirmed to be very effective for the removal of heavy metals from Middle Eastern VR, Maya/Istmo VR and Maya VR. The extruded AC catalysts were produced by industrial manufacturing method. The application test of the extruded AC catalyst for ebullating-bed reactor as one of the commercially applicable reactors was carried out at the ebullating-bed pilot plant for 500h. The ebullition of the extruded AC catalyst was successfully traced and confirmed by existing {gamma}-ray density meter. The extruded AC catalyst showed stable performance with less sediment formation at an equivalent conversion by conventional alumina catalyst at commercial ebullating-bed unit. The degradation of the AC catalyst at the aging test was observed to be less than that of the conventional alumina catalyst. Thus, the AC catalyst was confirmed to be effective and suitable for upgrading of heavy oil, especially such heavy oils as Maya, which contains much heavy metals.

Reactivation of a tin oxide-containing catalyst

Science.gov (United States)

Upchurch, Billy T. (Inventor); Miller, Irvin M. (Inventor); Brown, Kenneth G. (Inventor); Hess, Robert V. (Inventor); Schryer, David R. (Inventor); Sidney, Barry D. (Inventor); Wood, George M. (Inventor); Paulin, Patricia A. (Inventor)

1989-01-01

A method for the reactivation of a tin oxide-containing catalyst of a CO.sub.2 laser is provided. First, the catalyst is pretreated by a standard procedure. When the catalyst experiences diminished activity during usage, the heated zone surrounding the catalyst is raised to a temperature which is the operating temperature of the laser and 400.degree. C. for approximately one hour. The catalyst is exposed to the same laser gas mixture during this period. The temperature of the heated zone is then lowered to the operating temperature of the CO.sub.2 laser.

Catalytic reduction of NO{sub x}; Katalytisk reduktion av NO{sub x}

Energy Technology Data Exchange (ETDEWEB)

Odenbrand, I. [Lund Univ. (Sweden). Dept. of Chemical Engineering

2001-10-01

In the project conventional and bio-modified SCR catalysts and the possibilities to regenerate deactivated ones have been studied. The catalysts were deactivated by use in commercial plants in the CFB furnaces at Brista and Vaexjoe and in the PC burner at Drefviken. The methods for regeneration that were applied were: a) washing with water, sulphuric acid or ammonium salts and b) sulphation by sulphur dioxide. The catalysts are deactivated when used by the enrichment of alkali and alkaline earth metals on their surface and in their pores. At bio-fuelled furnaces the accumulation of potassium is the major problem. When these deactivated catalysts are washed with water, potassium and some acidic components (sulphates) are dissolved from both types of catalysts. In addition small amounts of the active component vanadium are dissolved. When sulphuric acid is used an optimal activity after regeneration is obtained at 0.5 M sulphuric acid. At higher concentrations the leached amount of vanadia is too large counteracting the removal of potassium. The same tendency, with an optimum at 0.5 M, was obtained when the washing was performed with ammonium sulphate solutions. It is not possible to regenerate strongly deactivated catalysts by only washing with water. It is necessary to either wash with sulphuric acid/ammonium sulphate solutions or to sulphate with sulphur dioxide after washing with water. The thermal stability of introduced sulphate groups is good at least up to 420 deg C. A catalyst, which has been sulphated and contains large amounts of potassium, is not chemically stable in an SCR environment (in the presence of ammonia, nitric oxide and water) at 400 deg C. At 350 deg C it is stable however. Electron microscopy using X-ray analysis showed that a washing time of 60 minutes was enough to remove all visual deposits from the catalyst surface. The analysis did also show that potassium is distributed homogeneously throughout the monolith material both before and

In situ Transmission Electron Microscopy of catalyst sintering

DEFF Research Database (Denmark)

DeLaRiva, Andrew T.; Hansen, Thomas Willum; Challa, Sivakumar R.

2013-01-01

Recent advancements in the field of electron microscopy, such as aberration correctors, have now been integrated into Environmental Transmission Electron Microscopes (TEMs), making it possible to study the behavior of supported metal catalysts under operating conditions at atomic resolution. Here......, we focus on in situ electron microscopy studies of catalysts that shed light on the mechanistic aspects of catalyst sintering. Catalyst sintering is an important mechanism for activity loss, especially for catalysts that operate at elevated temperatures. Literature from the past decade is reviewed...... along with our recent in situ TEM studies on the sintering of Ni/MgAl2O4 catalysts. These results suggest that the rapid loss of catalyst activity in the earliest stages of catalyst sintering could result from Ostwald ripening rather than through particle migration and coalescence. The smallest...

Catalyst for hydrocarbon conversion

International Nuclear Information System (INIS)

Duhaut, P.; Miquel, J.

1975-01-01

A description is given for a catalyst and process for hydrocarbon conversions, e.g., reforming. The catalyst contains an alumina carrier, platinum, iridium, at least one metal selected from uranium, vanadium, and gallium, and optionally halogen in the form of metal halide of one of the aforesaid components. (U.S.)

Development of GREET Catalyst Module

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States); Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States); Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-09-01

In this report, we develop energy and material flows for the production of five different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5], Mo/Co/ γ-Al₂O3, and Pt/ γ-Al₂O₃) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module.

Novel non-platinum metal catalyst material

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

Directory of Open Access Journals (Sweden)

Galip Akay

2016-05-01

Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano

Controlled Oxygen Chemisorption on an Alumina Supported Rhodium Catalyst. The Formation of a New Metal-Metal Oxide Interface Determined with EXAFS.

NARCIS (Netherlands)

Koningsberger, D.C.; Martens, J.H.A.; Prins, R.

1989-01-01

An alumina-supported rhodium catalyst has been studied with EXAFS. After reduction and evacuation, oxygen was admitted at 100 and 300 K. EXAFS spectra of the catalyst after oxygen admission at 100 K indicated the beginning of oxidation. At 300 K only a small part of the rhodium particles remained

Oxidative regeneration of Ni-Mo-gamma-Al/sub 2/O/sub 3/ catalysts used for hydrotreatment of coal-derived oil

Energy Technology Data Exchange (ETDEWEB)

Yoshimura, Yuji; Furimsky, Edward; Sato, Toshio; Shimada, Hiromichi; Matsubayashi, Nobuyuki; Nishijima, Akio

1986-10-23

In order to easily find the oxidative reaction characteristics of carbonaceous materials and sulfur deposited on the catalysts used for hydrogenation, oxidative regeneration behavior as studied with a fixed bed reactor, and the surfaces of the spent catalysts were analyzed by XPS to find the changes in form of active metals and sulfur on the catalysts. Ni-Mo-gamma-Al/sub 2/O/sub 3/ catalysts were used for hydrotreatment of primary coal-derived oil from Morwell coal. The spent catalysts were extracted by THF, dried and crushed into 100-200 mesh powder. The relation between catalyst regeneration temperature and CO/sub 2/ or SO/sub 2/, the relation between generated gas compositions and temperature in regeneration, and the activation energy of carbon and sulfur in the catalysts for oxidative reaction were indicated with data. As a result, it was found that a part of the active metals turned to sulfates by hydrotreatment and the residual sulfur existed in form of sulfate. ( 6 figs, 2 tabs, 4 refs )

Hydroprocessing full-range of heavy oils and bitumen using ultradispersed catalysts at low severity

Science.gov (United States)

Peluso, Enzo

The progressive exhaustion of light crude oils is forcing the petroleum industry to explore new alternatives for the exploitation of unconventional oils. New approaches are searching for technologies able to produce, transport and refine these feedstocks at lower costs, in which symbiotic processes between the enhanced oil recovery (EOR) and the conventional upgrading technologies are under investigation. The process explored in this thesis is an interesting alternative for in-situ upgrading of these crude oils in the presence of ultradispersed (UD) catalysts, which are included as a disperse phase able to circulate along with the processed feed. The objectives of this work are: (a) study the performance of UD catalysts in the presence of a full range (non fractioned) heavy oil and bitumen and (b) evaluate the recyclability of the UD catalysts. Four different heavy crude oils were evaluated in the presence with UD catalysts at a total pressure of 2.8 MPa, residence time of 8 hours and reaction temperatures from 360 up to 400ºC. Thermal and catalytic hydro-processing were compared in terms of conversion and product stability. A comparison between the different crude oils was additionally derived in terms of SARA, initial micro-carbon content and virgin oil stability among other properties. Advantages of catalytic hydro-processing over thermal hydro-processing were evidenced, with UD catalysts playing an essential hydrogenating role while retarding coke formation; microcarbon and asphaltenes reduction in the presence of UD catalysts was observed. To evaluate the feasibility of recycling the UD catalysts, a micro-slurry recycled unit was developed as part of this research. These main results showed: (a) a successful design of this unit, (b) that temperature, LHSV and fractional recycling ratio have more impact on VGO conversion, while pressure has almost no effect, and (c) an UD catalysts agglomeration process was detected, however this process is slow and reversible.

exchanged Mg-Al hydrotalcite catalyst

Indian Academy of Sciences (India)

) catalysts, ... The catalyst can be easily separated by simple filtration ... surface area by the single-point N2 adsorption method ... concentration of carbonate anions (by treating the cat- .... hydrotalcite phase along with copper hydroxide and.

Two Catalysts for Selective Oxidation of Contaminant Gases

Science.gov (United States)

Wright, John D.

2011-01-01

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia. The first catalyst is of the supported-precious-metal type. This catalyst is highly active for the oxidation of halocarbons, hydrocarbons, and oxygenates at low concentrations in air. This catalyst is more active for the oxidation of hydrocarbons and halocarbons than are competing catalysts developed in recent years. This catalyst completely converts these airborne contaminant gases to carbon dioxide, water, and mineral acids that can be easily removed from the air, and does not make any chlorine gas in the process. The catalyst is thermally stable and is not poisoned by chlorine or fluorine atoms produced on its surface during the destruction of a halocarbon. In addition, the catalyst can selectively oxidize ammonia to nitrogen at a temperature between 200 and 260 C, without making nitrogen oxides, which are toxic. The temperature of 260 C is higher than the operational temperature of any other precious-metal catalyst that can selectively oxidize ammonia. The purpose of the platinum in this catalyst is to oxidize hydrocarbons and to ensure that the oxidation of halocarbons goes to completion. However, the platinum exhibits little or no activity for initiating the destruction of halocarbons. Instead, the attack on the halocarbons is initiated by the support. The support also provides a high surface area for exposure of the platinum. Moreover, the support resists deactivation or destruction by halogens released during the destruction of halocarbons. The second catalyst is of the supported- metal-oxide type. This catalyst can selectively oxidize ammonia to

Polyfunctional catalyst for processiing benzene fractions

Energy Technology Data Exchange (ETDEWEB)

G. Byakov; B.D. Zubitskii; B.G. Tryasunov; I.Ya. Petrov [Kuznetsk Basin State Technical University, Kemerovo (Russian Federation)

2009-05-15

A by-product of the coke industry is a raw benzene fraction benzene- 1 which may serve as for catalytic processes. The paper reports a study on the influence of the composition and temperatures on the activity and selectivity of NiO-V{sub 2}O{sub 6}-MoO{sub 3}/{gamma}-Al{sub 2}O{sub 3} catalysts and the corresponding binary and tertiary subsystems are studied by a pulse method in model reactions; the hydrodealkylating of toluene and the hydrodesulfurizing of thioprhene. The optimal catalyst composition is established. The new catalyst is compared with industrial catalysts.

Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.