Download or read book NO sub X REDUCTION BEHAVIOR OF ALUMINA AND ZEOLITE CATALYSTS IN COMBINATION WITH NON THERMAL PLASMA written by and published by . This book was released on 2000 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean burn gasoline and diesel engines provide improved fuel economy when compared to engines operating under stoichiometric fuel/air conditions. At the same time, lean burn and diesel engines present a problem for emission control. Because they operate under oxidizing conditions, the conventional three-way catalyst is not effective in NOx reduction [1,2]. In addition, the wide temperature range of automobile exhaust gases present a challenge for catalyst design. The temperature of exhaust gases from a light duty diesel engine can vary from 150 to 500 C, depending on the operating conditions. To date, a catalyst that operates with high NOx conversion efficiency over the entire operating range has not been found. Non-thermal plasma assisted catalysis has been shown to be a promising technology for NOx reduction in lean burn and diesel exhaust gases [3,4]. The approach exploited in this paper is to use a plasma in combination with several catalysts, each of which are active over unique temperature ranges. It was reported in the literature, that the one of the essential roles of plasma treatment is to oxidize NO to easier reducible NO2 [7]. In this contribution, the other important function of plasma treatment, namely partial oxidation of propylene, will be demonstrated.
Download or read book SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA ASSISTED CATALYSIS written by and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The control of NOx (NO and NO2) emissions from so-called ''lean-burn'' vehicle engines remains a challenge. In recent years, there have been a number of reports that show that a plasma device combined with a catalyst can reduce as high as 90% or more of NOx in simulated diesel and other ''lean-burn'' exhaust. In the case of propylene containing simulated diesel exhaust, the beneficial role of a plasma treatment is now thought to be due to oxidation of NO to NO2, and the formation of partially oxidized hydrocarbons that are more active for the catalytic reduction of NO2 than propylene. Thus, the overall system can be most usefully described as hydrocarbon selective catalytic reduction (SCR) enhanced by 'reforming' the exhaust with a non-thermal plasma (NTP) device. For plasma-enhanced catalysis, both zeolite- and alumina-based materials have shown high activity, albeit in somewhat different temperature ranges, when preceded by an NTP reactor. This paper will briefly describe our research efforts aimed at optimizing the catalyst materials for NTP-catalysis devices based, in part, on our continuing studies of the NTP- and catalytic-reaction mechanisms. Various alkali- and alkaline earth-cation-exchanged Y zeolites have been prepared, their material properties characterized, and they have been tested as catalytic materials for NOx reduction in laboratory NTP-catalysis reactors. Interestingly, NO2 formed in the plasma and not subsequently removed over these catalysts, will back-convert to NO, albeit to varying extents depending upon the nature of the cation. Besides this comparative reactivity, we will also discuss selected synthesis strategies for enhancing the performance of these zeolite-based catalyst materials. A particularly important result from our mechanistic studies is the observation that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, acetaldehyde has been found to be especially effective in the thermal reduction of both NO and NO2 over Ba- and Na-Y zeolite catalysts.
Download or read book Zeolite Catalysts in the Reduction of NO sub X in Lean Automotive Exhaust Gas Conditions written by Mika Huuhtanen and published by . This book was released on 2006 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book LEAN NO sub X REDUCTION BY PLASMA ASSISTED CATA written by and published by . This book was released on 2000 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The widespread use of light duty diesel engines in the United States would naturally lead to a large reduction of fuel consumption, due to their generally higher efficiency. By extension, savings in fuel consumption would decrease the total CO2 emitted from mobile sources. Although this is a desirable goal, at present a major stumbling block to increased diesel engine use is the difficulty in reducing noxious exhaust components, mainly NOx and particulates, to acceptable levels. We are studying the possibility of reducing NOx emissions through the combination of non-thermal plasma with appropriate catalysts. The broad outline of how this technique works has been worked out both experimentally and theoretically. 1-3 The presently accepted model is that a non-thermal plasma in the presence of water, oxygen and hydrocarbon will efficiently convert NO to NO2, while only partially oxidizing the hydrocarbon present. Some catalysts will reduce NO2 (but not necessarily NO) i n the presence of excess oxygen if the proper hydrocarbon is present. In this paper we report results using non-thermal plasma in conjunction with a commonly available zeolite catalyst, NaY, to treat synthetic diesel exhaust. We focus on details of the heterogeneous chemistry on NaY by comparing the thermal and plasma driven chemistry. EXPERIMENT Details of our experiment have been published elsewhere, so only a brief summary is included here. 4 Synthetic exhaust gas was created by blending gases from cylinders of known composition using mass flow controllers. Besides NO, the exhaust mixture included CO, CO2, propylene, water, oxygen and nitrogen. A typical mixture contained 6% oxygen, 2% water, and, unless otherwise noted, a 3:1 ratio of propylene to NOx. This corresponds to a 9:1 ratio on a C1 basis. CO and CO2 were sometimes included, but we found that their presence did not materially affect our results. For nitrogen balance experiments we omitted CO and CO2 and replaced the nitrogen bath gas with helium.
Download or read book Plasma assisted Catalytic Reduction of NO sub x sub written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many studies suggest that lean-NOx SCR proceeds via oxidation of NO to NO[not] by oxygen, followed by the reaction of the NO[not]with hydrocarbons. On catalysts that are not very effective in catalyzing the equilibration of NO+O[not] and NO[not], the rate of N[not] formation issubstantially higher when the input NOx is NO[not] instead of NO. The apparent bifunctional mechanism in the SCR ofNOx has prompted the use of mechanically mixed catalyst components, in which one component is used to accelerate theoxidation of NO to NO[not], and another component catalyzes the reaction between NO[not] and the hydrocarbon. Catalysts that previously wereregarded as inactive for NOx reduction could therefore become efficient when mixed with an oxidation catalyst. PreconvertingNO to NO[not] opens the opportunity for a wider range of SCR catalysts and perhaps improves the durability of these catalysts. This paperdescribes the use of a non-thermal plasma as an efficient means for selective partial oxidation of NO to NO[not]. When combined with sometypes of SCR catalyst, the plasma can greatly enhance the NOx reduction and eliminate some of the deficiencies encountered inan entirely catalyst-based approach. efficiency for reduction of NOsubx
Download or read book Highly basic Large pore Zeolite Catalysts for NOx Reduction at Low Temperatures written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A high-surface-area (greater than 600 m2/g), large-pore (pore size diameter greater than 6.5 angstroms), basic zeolite having a structure such as an alkali metal cation-exchanged Y-zeolite is employed to convert NO.sub.x contained in an oxygen-rich engine exhaust to N.sub. 2 and O.sub. 2. Preferably, the invention relates to a two-stage method and apparatus for NO.sub.x reduction in an oxygen-rich engine exhaust such as diesel engine exhaust that includes a plasma oxidative stage and a selective reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub. 2 in the presence of O.sub. 2 and added hydrocarbons. The second stage employs a lean-NO.sub.x catalyst including the basic zeolite at relatively low temperatures to convert such NO.sub. 2 to environmentally benign gases that include N.sub. 2, CO.sub. 2, and H.sub. 2 O.
Download or read book Plasma Catalysis written by Annemie Bogaerts and published by MDPI. This book was released on 2019-04-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
Download or read book NO sub X Reduction by Hydrocarbons and Hydrogen on Metal Oxide and Zeolite Based Catalysts in Lean Conditions written by Teuvo Maunula and published by . This book was released on 2007 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tiivistelmä.
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 NOx" that was published in Catalysts
Download or read book New Insights on Fe zeolite Catalysts for the Reduction of NO X with NH 3 written by Sarah Maria Maier and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalysts Deactivation Poisoning and Regeneration written by Luciana Lisi and published by MDPI. This book was released on 2019-10-01 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalyst lifetime represents one of the most crucial economic aspects in industrial catalytic processes, due to costly shutdowns, catalyst replacements, and proper disposal of spent materials. Not surprisingly, there is considerable motivation to understand and treat catalyst deactivation, poisoning, and regeneration, which causes this research topic to continue to grow. The complexity of catalyst poisoning obviously increases along with the increasing use of biomass/waste-derived/residual feedstocks and with requirements for cleaner and novel sustainable processes. This book collects 15 research papers providing insights into several scientific and technical aspects of catalyst poisoning and deactivation, proposing more tolerant catalyst formulations, and exploring possible regeneration strategies.
Download or read book Deactivation and Regeneration of Zeolite Catalysts written by M. Guisnet and published by World Scientific. This book was released on 2011 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: In chemical processes, the progressive deactivation of solid catalysts is a major economic concern and mastering their stability has become as essential as controlling their activity and selectivity. For these reasons, there is a strong motivation to understand the mechanisms leading to any loss in activity and/or selectivity and to find out the efficient preventive measures and regenerative solutions that open the way towards cheaper and cleaner processes. This book covers in a comprehensive way both the fundamental and applied aspects of solid catalyst deactivation and encompasses the state-of-the-art in the field of reactions catalyzed by zeolites. This particular choice is justified by the widespread use of molecular sieves in refining, petrochemicals and organic chemicals synthesis processes, by the large variety in the nature of their active sites (acid, base, acid-base, redox, bifunctional) and especially by their peculiar features, in terms of crystallinity, structural order and textural properties, which make them ideal models for heterogeneous catalysis. The aim of this book is to be a critical review in the field of zeolite deactivation and regeneration, by collecting a series of contributions by experts in the field which describe the factors, explain the techniques to study the causes and suggest methods to prevent (or limit) catalyst deactivation. At the same time, an anthology of commercial processes and exemplar cases provides the reader with theoretical insights and practical hints on the deactivation mechanisms and draws attention to the key role played by the loss of activity on process design and industrial practice.
Download or read book Die deutsche Fischindustrie in den Jahren 1938 bis 1942 written by and published by . This book was released on 1943 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In Situ M ssbauer Spectroscopic Studies of Iron exchanged Y zeolite Catalysts for the Selective Catalytic Reduction with Ammonia and Direct Decomposition of Nitric Oxide written by Ralf Schmidt and published by . This book was released on 1991 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
Download or read book Cerium ferrierite Catalyst Systems for Reduction of NOx in Lean Burn Engine Exhaust Gas written by Germaine Seijger and published by IOS Press. This book was released on 2002 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents of this Doctoral Dissertation include: NOx emission reduction from lean burn engines, automotive exhaust gas emissions, Reactions of NOx in the atmosphere Engine market share and sales trends, Ferrierite characteristics, synthesis and application, Characteristics of the group of FER framework structures, Screening of silver and cerium exchanged zeolite catalysts for the lean burn reduction of NOx with propene, Hydrocarbon NOx reduction in lean burn exhaust gas over Ce-FER catalysts, Approach to the kinetics of NOx reduction with propene over Ce-H-Ferrierite, In SITU preparation of ferrierite coatings on cordierite honeycomb supports, Concluding remarks
Download or read book Electro catalytic Reduction of NO Sub X written by and published by . This book was released on 1990 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this investigation, a stream containing nitric oxide has been subjected to intense electric fields in the presence of catalysts. The work has been conducted in two phases. In the first phase catalysts tested included steel, stainless steel, and gold plated stainless steel wools. The effect of parameters such as inlet nitric oxide concentration, oxygen and water vapor content, gas residence time and temperature on NO reduction have been studied. In the second phase, the effect of non-conducting materials such as glass wool as a catalyst on NO reduction has been investigated. Experiments were also conducted with no catalyst to study the advantage of catalyst use.
