Development Of A Catalyst For Selective Reduction Of Nox And Oxidation Of Co And Hydrocarbons

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Development of Catalyst for Selective Reduction of NOx and Oxidation of CO and Hydrocarbons

Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (455 download)

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Book Synopsis Development of Catalyst for Selective Reduction of NOx and Oxidation of CO and Hydrocarbons by :

Download or read book Development of Catalyst for Selective Reduction of NOx and Oxidation of CO and Hydrocarbons written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presently available technologies for control of engine NOx are not applicable in diesel engines and microns research projects are in progress in both the U.S. and Japan to find a practical method of catalytically reducing NOx in diesel exhaust. This report describes are laboratory scale testing of two possible methods of doing this. Tests were done with gas mixtures which simulated diesel exhaust. Of the two NOx control methods tested, one was found unpromising while the other gave promising results when propane was used as the NOx reducing agent. Since, however, the results with diesel fuel as the reducing agent were not promising, further development did not seem justified. It appears likely than the need to used diesel fuel is the NOx reductant in any practical system will be an issue in the other research projects now ongoing.

Selective Catalytic Reduction of NOx

Author : Oliver Kröcher
Publisher : MDPI
ISBN 13 : 3038973645
Total Pages : 281 pages
Book Rating : 4.0/5 (389 download)

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Book Synopsis Selective Catalytic Reduction of NOx by : Oliver Kröcher

Download or read book Selective Catalytic Reduction of NOx written by Oliver Kröcher and published by MDPI. This book was released on 2018-12-14 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NO_x" that was published in Catalysts

Two-stage Catalytic Reduction of NOx with Hydrocarbons

Author : Umit S. Ozkan
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Two-stage Catalytic Reduction of NOx with Hydrocarbons by : Umit S. Ozkan

Download or read book Two-stage Catalytic Reduction of NOx with Hydrocarbons written by Umit S. Ozkan and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A two-stage system for the catalytic reduction of NO from lean-burn natural gas reciprocating engine exhaust is investigated. Each of the two stages uses a distinct catalyst. The first stage is oxidation of NO to NO{sub 2} and the second stage is reduction of NO{sub 2} to N{sub 2} with a hydrocarbon. The central idea is that since NO{sub 2} is a more easily reduced species than NO, it should be better able to compete with oxygen for the combustion reaction of hydrocarbon, which is a challenge in lean conditions. Early work focused on demonstrating that the N{sub 2} yield obtained when NO{sub 2} was reduced was greater than when NO was reduced. NO{sub 2} reduction catalysts were designed and silver supported on alumina (Ag/Al{sub 2}O{sub 3}) was found to be quite active, able to achieve 95% N{sub 2} yield in 10% O{sub 2} using propane as the reducing agent. The design of a catalyst for NO oxidation was also investigated, and a Co/TiO{sub 2} catalyst prepared by sol-gel was shown to have high activity for the reaction, able to reach equilibrium conversion of 80% at 300 C at GHSV of 50,000h{sup -1}. After it was shown that NO{sub 2} could be more easily reduced to N{sub 2} than NO, the focus shifted on developing a catalyst that could use methane as the reducing agent. The Ag/Al{sub 2}O{sub 3} catalyst was tested and found to be inactive for NOx reduction with methane. Through iterative catalyst design, a palladium-based catalyst on a sulfated-zirconia support (Pd/SZ) was synthesized and shown to be able to selectively reduce NO{sub 2} in lean conditions using methane. Development of catalysts for the oxidation reaction also continued and higher activity, as well as stability in 10% water, was observed on a Co/ZrO{sub 2} catalyst, which reached equilibrium conversion of 94% at 250 C at the same GHSV. The Co/ZrO{sub 2} catalyst was also found to be extremely active for oxidation of CO, ethane, and propane, which could potential eliminate the need for any separate oxidation catalyst. At every stage, catalyst synthesis was guided by the insights gained through detailed characterization of the catalysts using many surface and bulk analysis techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, Temperature-programmed Reduction, Temperature programmed Desorption, and Diffuse Reflectance InfraRed Fourier Transform Spectroscopy as well as steady state reaction experiments. Once active catalysts for each stage had been developed, a physical mixture of the two catalysts was tested for the reduction of NO with methane in lean conditions. These experiments using a mixture of the catalysts produced N2 yields as high as 90%. In the presence of 10% water, the catalyst mixture produced 75% N{sub 2} yield, without any optimization. The dual catalyst system developed has the potential to be implemented in lean-burn natural gas engines for reducing NOx in lean exhaust as well as eliminating CO and unburned hydrocarbons without any fuel penalty or any system modifications. If funding continues, future work will focus on improving the hydrothermal stability of the system to bring the technology closer to application.

DEVELOPMENT OF IMPROVED CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDES WITH HYDROCARBONS.

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis DEVELOPMENT OF IMPROVED CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDES WITH HYDROCARBONS. by :

Download or read book DEVELOPMENT OF IMPROVED CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDES WITH HYDROCARBONS. written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant work has been done by the investigators on the cerium oxide-copper oxide based sorbent/catalysts for the combined removal of sulfur and nitrogen oxides from the flue gases of stationary sources. Evaluation of these sorbents as catalysts for the selective reduction of NO[sub x] gave promising results with methane. Since the replacement of ammonia by methane is commercially very attractive, in this project, the effect of promoters on the activity and selectivity of copper oxide/cerium oxide-based catalysts and the reaction mechanism for the SCR with methane was investigated. Unpromoted and promoted catalysts were investigated for their SCR activity with methane in a microreactor setup and also, by the temperature-programmed desorption (TPD) technique. The results from the SCR experiments indicated that manganese is a more effective promoter than the other metals (Rh, Li, K, Na, Zn, and Sn) for the supported copper oxide-ceria catalysts under study. The effectiveness of the promoter increased with the increase in Ce/Cu ratio. Among the catalysts tested, the Cu1Ce3 catalyst promoted with 1 weight% Mn was found to be the best catalyst for the SCR of NO with methane. This catalyst was subjected to long-term testing at the facilities of our industrial partner TDA Research. TDA report indicated that the performance of this catalyst did not deteriorate during 100 hours of operation and the activity and selectivity of the catalyst was not affected by the presence of SO[sub 2]. The conversions obtained by TDA were significantly lower than those obtained at Hampton University due to the transport limitations on the reaction rate in the TDA reactor, in which 1/8th inch pellets were used while the Hampton University reactor contained 250-425-[micro]m catalyst particles. The selected catalyst was also tested at the TDA facilities with high-sulfur heavy oil as the reducing agent. Depending on the heavy oil flow rate, up to 100% NO conversions were obtained. The temperature programmed desorption studies a strong interaction between manganese and cerium. Presence of manganese not only enhanced the reduction rate of NO by methane, but also significantly improved the N[sub 2] selectivity. To increase the activity of the Mn-promoted catalyst, the manganese content of the catalyst need to be optimized and different methods of catalyst preparation and different reactor types need to be investigated to lower the transport limitations in the reactor.

Emissions Control Catalysis

Author : Ioannis V. Yentekakis
Publisher : MDPI
ISBN 13 : 3039360361
Total Pages : 448 pages
Book Rating : 4.0/5 (393 download)

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Book Synopsis Emissions Control Catalysis by : Ioannis V. Yentekakis

Download or read book Emissions Control Catalysis written by Ioannis V. Yentekakis and published by MDPI. This book was released on 2020-06-18 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The important advances achieved over the past years in all technological directions (industry, energy, and health) contributing to human well-being are unfortunately, in many cases, accompanied by a threat to the environment, with photochemical smog, stratospheric ozone depletion, acid rain, global warming, and finally climate change being the most well-known major issues. These are the results of a variety of pollutants emitted through these human activities. The indications show that we are already at a tipping point that might lead to non-linear and sudden environmental change on a global scale. Aiming to tackle these adverse effects in an attempt to mitigate any damage that has already occurred and to ensure that we are heading toward a cleaner (green) and sustainable future, scientists around the world are developing tools and techniques to understand, monitor, protect, and improve the environment. Emissions control catalysis is continuously advancing, providing novel, multifunctional, and optimally promoted using a variety of methods, nano-structured catalytic materials, and strategies (e.g., energy chemicals recycling, cyclic economy) that enable us to effectively control emissions, either of mobile or stationary sources, improving the quality of air (outdoor and indoor) and water and the energy economy. Representative cases include the abatement and/or recycling of CO2, CO, NOx, N2O, NH3, CH4, higher hydrocarbons, volatile organic compounds (VOCs), particulate matter, and specific industrial emissions (e.g., SOx, H2S, dioxins aromatics, and biogas). The “Emissions Control Catalysis” Special Issue has succeeded in collecting 22 high-quality contributions, included in this MDPI open access book, covering recent research progress in a variety of fields relevant to the above topics and/or applications, mainly on: (i) NOx catalytic reduction from cars (i.e., TWC) and industry (SCR) emissions; (ii) CO, CH4, and other hydrocarbons removal, and (iii) CO2 capture/recirculation combining emissions control with added-value chemicals production.

Multiphase Catalysts for Selective Reduction of NOx with Hydrocarbons

Author : Sergio Eduardo Maisuls
Publisher :
ISBN 13 : 9789036514293
Total Pages : 132 pages
Book Rating : 4.5/5 (142 download)

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Book Synopsis Multiphase Catalysts for Selective Reduction of NOx with Hydrocarbons by : Sergio Eduardo Maisuls

Download or read book Multiphase Catalysts for Selective Reduction of NOx with Hydrocarbons written by Sergio Eduardo Maisuls and published by . This book was released on 2000 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Development of a Water Resistant NOx Reduction Catalyst

Author : Christopher M. Rodenbush
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (86 download)

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Book Synopsis Development of a Water Resistant NOx Reduction Catalyst by : Christopher M. Rodenbush

Download or read book Development of a Water Resistant NOx Reduction Catalyst written by Christopher M. Rodenbush and published by . This book was released on 2003 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

New Heterogeneous Catalysts for the Selective Reduction of NOx Under Lean Conditions. Final Report

Author :
Publisher :
ISBN 13 :
Total Pages : 10 pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis New Heterogeneous Catalysts for the Selective Reduction of NOx Under Lean Conditions. Final Report by :

Download or read book New Heterogeneous Catalysts for the Selective Reduction of NOx Under Lean Conditions. Final Report written by and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The original goal of this program was the identification and design of new noble-metal-based catalysts for the selective catalytic reduction of nitric oxide by hydrocarbons under excess oxygen (i.e., ''lean'') conditions (HC-SCR). Work conducted in the first funding cycle of this award (i.e., 1997-2000) was successful in allowing us to develop an understanding of the fundamental surface chemistry taking place during the adsorption and reaction of nitrogen oxides and propylene on the surface of supported noble metal catalysts. Both experimental results collected in our own group as well as molecular simulation results published by Professor Neurock suggested that in order to improve the performance of the Pt catalysts--in terms of the nitrogen selectivity and the temperature window of operation-- it was necessary to introduce a second metal. However, synthesizing such catalysts with the metals of interest (i.e., Pt-Au, Pt-Ru, Pt-Rh, etc.) with some degree of control of the structure and composition of the resulting supported metal particles is in itself a research challenge. Consequently, the bulk of our efforts during the second funding cycle of this award (covered by this report) was shifted to the use of organometallic cluster precursors for the synthesis on novel bimetallic catalysts. During this time we have also continued to maintain an interest in NOx abatement, but have redirected our efforts from the HC-SCR process to the more promising from a commercial standpoint NOx Storage Reduction (NSR) approach.

NOx Trap Catalysts and Technologies

Author : Luca Lietti
Publisher : Royal Society of Chemistry
ISBN 13 : 1788013239
Total Pages : 514 pages
Book Rating : 4.7/5 (88 download)

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Book Synopsis NOx Trap Catalysts and Technologies by : Luca Lietti

Download or read book NOx Trap Catalysts and Technologies written by Luca Lietti and published by Royal Society of Chemistry. This book was released on 2018-06-13 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will be the first to comprehensively present the current research on catalysts used for NOx abatement in lean exhausts.

Studies on the Reduction of Nitrous Oxide Formation in NOx-trap Catalysts

Author : Javier Mena Casanova
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (112 download)

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Book Synopsis Studies on the Reduction of Nitrous Oxide Formation in NOx-trap Catalysts by : Javier Mena Casanova

Download or read book Studies on the Reduction of Nitrous Oxide Formation in NOx-trap Catalysts written by Javier Mena Casanova and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Current society has become more concerned about being environmentally friendly. Catalytic gas after treatment is one of the solutions adopted to reduce pollutant emissions from a combustion engine. A Three Way NOx Storage Catalytic Converter (TWNSC) is a new development of Daimler AG together with Umicore AG [1]. It consists of a Catalyst with some of the main properties of a Three Way Catalyst (TWC) together with NOx storage capacity (lean-NOx trap). This catalyst is used in Otto direct-injection engines with lean/rich operation mode. This technology can reduce fuel consumption in a range of 10%. During lean engine operation time, high quantities of Nitrogen Oxides (NOx) are generated. In presence of a TWNSC, this NOx can be stored. When the engine changes to rich operating mode, the amount of NOx in exhaust gases decreases become rich of unburned hydrocarbons (HC), hydrogen (H2) and carbon monoxide (CO) that can reduce the NOx stored. However, during NOx reduction, formation of undesired byproducts occur. That is the case of nitrous oxide (N2O) and ammonia (NH3). In this Master thesis, studies on the reduction of nitrous oxide formation in Three Way NOx Storage Catalytic Converter are performed. Studies on N2O formation during catalyst performance have not been widely studied and published. In this master thesis, lean/rich experimentations on two new TWNSC (catalyst A and B) are performed to find conditions in which N2O formation can be reduced. Experiments are performed in a test bench where lean gases are provided by a 1- cylinder-engine and rich gases from synthetic gas mixtures. At the beginning of the master thesis, two preliminary investigations are performed. The first consists of the calculation of Oxygen Storage Capacity (OSC) of a cylindrical sample (25 mm diameter, 30 mm length) of catalyst A and B. The results of the experiment show that catalyst B has less Oxygen Storage Capacity. The experiment consisted on applying a flow of 12,5 l/min of Oxygen (O2) in nitrogen (N2) (0,4% by volume) through the previously reduced sample. An average of 0,3 g./l.cat. less oxygen is stored in catalyst B for temperatures of 300, 350 and 400 oC. At 300oC, catalyst A stores 1,44 g/l.cat. compared to the 0,93 g/l.cat. in catalyst B. The second preliminary investigation consists of determining the temperature in which the Diesel Oxidation Catalyst (DOC) in reactor 1 has to operate. The objective of this DOC is to oxidize the HC and maintain the original NO2/NOx ratio from the engine exhaust gases. During lean mode, gases from a 1-cylinder-engine (Hatz-motor [2]) are used. NOx and HC concentrations are analyzed for a range of temperatures from 150 to 650 oC. It is concluded that a temperature of 620 oC has to be reached in reactor one to get rid of HC and maintain the NO2/NOx ratio of the bypass exhaust gases (2% of NO2 in NOx). After the preliminary investigations, the first objective is getting to know the basic performance of the two different TWNSC. Lean/rich experimentations are performed on both samples A and B at the range of temperatures from 150oC to 450oC. Lean/rich timing is set on 120/15 seconds respectively. In addition, three different rich gas mixtures (lambdas 0,95, 0,9 and 0,82) have been used for the rich mode. Results show that for lambda 0,95 less N2O is generated (0,06 g/l.cat. at 300oC in catalyst A). The minimum N2O detected is at catalyst B at temperatures of 400 and 450oC (0,01 and 0,00 g/l.cat.). The main part of the Master Thesis consists of four different experimentations that have the objective to find any reduction in N2O formation: 1. N2O formation studies with lean/rich experimentations at modified TWNSC catalysts. Instead of the 30 mm sample previously used, two 15 mm samples are used together. Modifications are applied on the first 15 mm sample and consist on five perforations (2 mm diameter) and the introduction of an uncoated central part section. These modifications try to increase reductants velocity during rich mode. Results show a decrease in N2O formation in the experiment with 15 mm uncoated catalyst A together with another 15 mm catalyst A. An average of 2,8 g/l.cat. of N2O reduction is obtained at temperature of 300oC. In addition, an increase of NOx conversion efficiency has been detected: for the same sample and temperature an average increase of 20% NOx performance 2. N2O formation studies with lean/rich experimentations at a combination of catalysts A and B together. It is concluded that the combination of catalyst A and B does not have a beneficial effect on N2O formation. 3. N2O formation studies with lean/rich experimentations with variation of rich time period. The objective is to see if the reduction of rich time period has an effect on N2O formation. 4. Lean/rich experimentations with variation of the lambda during rich period. The objective is to see if a reduction in N2O is obtained with these variations. For low temperatures (150oC and 200oC) a diminution in N2O formation is appreciated (0,05 g/l.cat to 0,04 g./l.cat at 150oC for 30 mm TWNSCA with uncoated section). This Master Thesis represents a base line study for further investigations on N2O formation on TWNSC. Catalyst modifications are a feasible solution for N2O diminution as well as NOx conversion efficiency. These results encourage further experimentations with these current and other new catalyst modifications. Variation of lambda during rich period and variation of the rich time period are variables that can have a relevant role.

Nitrogen oxides (NOx) why and how they are controlled

Author :
Publisher : DIANE Publishing
ISBN 13 : 1428902805
Total Pages : 57 pages
Book Rating : 4.4/5 (289 download)

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Download or read book Nitrogen oxides (NOx) why and how they are controlled written by and published by DIANE Publishing. This book was released on 1999 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:

NOx Reduction with Hydrocarbons Under Oxidizing Conditions Over Alumina Supported Metal Catalysts

Author : Erol Seker
Publisher :
ISBN 13 :
Total Pages : 338 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis NOx Reduction with Hydrocarbons Under Oxidizing Conditions Over Alumina Supported Metal Catalysts by : Erol Seker

Download or read book NOx Reduction with Hydrocarbons Under Oxidizing Conditions Over Alumina Supported Metal Catalysts written by Erol Seker and published by . This book was released on 2000 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The Chemistry of Pincer Compounds

Author : David Morales-Morales
Publisher : Elsevier
ISBN 13 : 0080545157
Total Pages : 467 pages
Book Rating : 4.0/5 (85 download)

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Book Synopsis The Chemistry of Pincer Compounds by : David Morales-Morales

Download or read book The Chemistry of Pincer Compounds written by David Morales-Morales and published by Elsevier. This book was released on 2011-08-11 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pincer complexes are formed by the binding of a chemical structure to a metal atom with at least one carbon-metal bond. Usually the metal atom has three bonds to a chemical backbone, enclosing the atom like a pincer. The resulting structure protects the metal atom and gives it unique properties.The last decade has witnessed the continuous growth in the development of pincer complexes. These species have passed from being curiosity compounds to chemical chameleons able to perform a wide variety of applications. Their unique metal bound structures provide some of the most active catalysts yet known for organic transformations involving the activation of bonds. The Chemistry of Pincer Compounds details use of pincer compounds including homogeneous catalysis, enantioselective organic transformations, the activation of strong bonds, the biological importance of pincer compounds as potential therapeutic or pharmaceutical agents, dendrimeric and supported materials. * Describes the chemistry and applications of this important class of organometallic and coordination compounds* Covers the areas in which pincer complexes have had an impact* Includes information on more recent and interesting pincer compounds not just those that are well-known

Atlas of Zeolite Framework Types

Author : Ch. Baerlocher
Publisher : Elsevier
ISBN 13 : 0080554342
Total Pages : 405 pages
Book Rating : 4.0/5 (85 download)

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Book Synopsis Atlas of Zeolite Framework Types by : Ch. Baerlocher

Download or read book Atlas of Zeolite Framework Types written by Ch. Baerlocher and published by Elsevier. This book was released on 2007-09-12 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolite scientists, whether they are working in synthesis, catalysis, characterization or application development, use the Atlas of Zeolite Framework Types as a reference. It describes the main features of all of the confirmed zeolite framework structures, and gives references to the relevant primary structural literature. Since the last edition 34 more framwork types have been approved and are described in this new edition. A further new feature will be that characteristic building units will be listed for each of the framework types.Zeolites and their analogs are used as desiccants, as water softeners, as shape-selective acid catalysts, as molecular sieves, as concentrators of radioactive isotopes, as blood clotting agents, and even as additives to animal feeds. Recently, their suitability as hosts for nanometer spacing of atomic clusters has also been demonstrated. These diverse applications are a reflection of the fascinating structures of these microporous materials. Each time a new zeolite framework structure is reported, it is examined by the Structure Commission of the International Zeolite Association (IZA-SC), and if it is found to be unique and to conform to the IZA-SC's definition of a zeolite, it is assigned a 3-letter framework type code. This code is part of the official IUPAC nomenclature for microporous materials. The Atlas of Zeolite Framework Types is essentially a compilation of data for each of these confirmed framework types. These data include a stereo drawing showing the framework connectivity, features that characterize the idealized framework structure, a list of materials with this framework type, information on the type material that was used to establish the framework type, and stereo drawings of the pore openings of the type material. Clear stereo drawings of each of the framework types Description of the features of the framework type, allowing readers to quickly see if the framework type is suitable to their needs References to isotypic materials, readers can quickly identify related materials and consult the appropriate reference

BIFUNCTIONAL CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NO BY HYDROCARBONS.

Author :
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis BIFUNCTIONAL CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NO BY HYDROCARBONS. by :

Download or read book BIFUNCTIONAL CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NO BY HYDROCARBONS. written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Novel bifunctional catalysts combining two active phases, typically Cu-ZSM-5 and a modifier, were prepared and tested for the selective catalytic reduction of nitrogen oxides using propylene in order to overcome the hindering effects of water typically seen for single-phase catalysts such as Cu-ZSM-5. The catalysts were made by typical preparation techniques, but parameters could be varied to influence the catalyst. The physical characterization of the materials showed that the modification phase was added strictly to the external surface of the zeolite without hindering any internal surface area. Chemical characterization by temperature programmed reactions, DRIFTS and x-ray absorption spectroscopy indicated strong interaction between the two phases, primarily producing materials that exhibited lower reduction temperatures. Two improvements in NOx reduction activity (1000 ppm NO, 1000 ppm C3H6, 2% O2, 30,000 hr-1 GHSV) were seen for these catalysts compared with Cu- ZSM-5: a lower temperature of maximum NOx conversion activity (as low at 250 C), and an enhancement of activity when water was present in the system. The use of a second phase provides a way to further tune the properties of the catalyst in order to achieve mechanistic conditions necessary to maximize NOx remediation.

Characterization of Competitive Oxidation Reactions Over a Model Pt-Pd/Al2O3 Diesel Oxidation Catalyst

Author : Karishma Vistasp Irani
Publisher :
ISBN 13 :
Total Pages : 74 pages
Book Rating : 4.:/5 (613 download)

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Book Synopsis Characterization of Competitive Oxidation Reactions Over a Model Pt-Pd/Al2O3 Diesel Oxidation Catalyst by : Karishma Vistasp Irani

Download or read book Characterization of Competitive Oxidation Reactions Over a Model Pt-Pd/Al2O3 Diesel Oxidation Catalyst written by Karishma Vistasp Irani and published by . This book was released on 2009 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been a growing interest in using lean-burn engines due to their higher fuel economy and associated lower CO2 emissions. However, there are challenges in reducing NOX in an O2-rich (lean-burn) exhaust, and in low temperature soot oxidation. NOX storage/reduction (NSR) and selective catalytic reduction (SCR) are commercial NOX reduction technologies, and both are more efficient with levels of NO2 that are higher than those that are in engine exhaust (engine-out NO2 levels are ~10% of the total NOX). Therefore diesel oxidation catalysts are installed upstream of these technologies to provide NO2 through NO oxidation. The motivation behind this research project was two-fold. The first was to gain a better understanding of the effect of hydrocarbons on NO oxidation over a monolithic diesel oxidation catalyst. The second was to spatially resolve competitive oxidation reactions as a function of temperature and position within the same diesel oxidation catalyst (as that used in the first part). A technique known as spatially resolved capillary-inlet mass spectrometry (SpaciMS) was used to measure the gas concentrations at various positions within the catalyst. Diesel engine exhaust contains a mixture of compounds including NO, CO and various hydrocarbons, which react simultaneously over a catalyst, and each can influence the oxidation rates of the others. While studying the effect of hydrocarbons on NO oxidation in this project, propylene was found to have an apparent inhibition effect on NO oxidation, which increased with increasing propylene concentration. This apparent inhibition is a result of the NO2, as a product of NO oxidation, reacting with the propylene as an oxidant. Experiments with NO2 demonstrate a significant temperature decrease in the onset of NO2 reduction when propylene was present, which decreased further with increasing amounts of propylene, verifying NO2 as an oxidant. Similar results were observed with m-xylene and dodecane addition as well. The results also demonstrate that NO2 was consumed preferentially relative to O2 during hydrocarbon oxidation. With low inlet levels of O2, it was evident that the addition of NO2 had an apparent inhibition effect on propylene oxidation after the onset of NO2 reduction. This subsequent inhibition was due to the NO formed, demonstrating that C3H6 results in reduced NO2 outlet levels while NO inhibits C3H6 oxidation. The development of new models as well as validation of existing models requires the ability to spatially resolve oxidation reactions within a monolith. Spatially-resolved data will also give catalyst manufacturers insight into the location of active fronts, thereby directing the design of more efficient catalysts. In this research project, spatially resolving the oxidation reactions demonstrated that H2 and CO are oxidized prior to C3H6 and C12H26 and clearly show back-to-front ignition of the reductant species. An enhancement in NO oxidation was observed at the same time as dodecane oxidation light off, likely related to dodecane partial oxidation products.

Oxidation Catalysis in Environmental Applications

Author : Matthew Maurice Yung
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (182 download)

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Book Synopsis Oxidation Catalysis in Environmental Applications by : Matthew Maurice Yung

Download or read book Oxidation Catalysis in Environmental Applications written by Matthew Maurice Yung and published by . This book was released on 2007 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The environmental applications of oxidation catalysis were examined as part of a two-stage strategy for the reduction of nitrogen oxides (NOx) and also for the removal of carbon monoxide from hydrogen streams. Cobalt-based catalysts were examined. Reduction of NOx, Co/TiO2 and Co/ZrO2 were studied for the oxidation of NO to NO2 in excess oxygen. NO oxidation was studied as the first step in a two-step catalytic scheme where NO is oxidized to NO2 and, in turn, NO2 is reduced with CH4 to N2 under lean conditions. Catalysts were prepared by sol-gel and incipient-wetness impregnation techniques. It was found that increasing the calcination temperature had an adverse effect on the activity of the IWI catalysts. Catalyst characterization showed higher activity for NO oxidation on Co/ZrO2 than on Co/TiO2 which was observed to correlate with the formation of the Co3O4 phase. For the preferential oxidation of CO, cobalt on several metal oxide supports were investigated and showed the highest activity on Co/ZrO2. A variety of reaction experiments were performed to examine the effects of reactant concentrations, residence time, and temperature on the CO conversion and O2 selectivity to CO2.