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High Temperature Water Gas Shift Reaction Over Cr Free Fe Al Catalysts Promoted With First Row Transition Metals
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Book Synopsis High-temperature Water-gas Shift Reaction Over Cr-free Fe-Al Catalysts Promoted with First Row Transition Metals by : Sittichai Natesakhawat
Download or read book High-temperature Water-gas Shift Reaction Over Cr-free Fe-Al Catalysts Promoted with First Row Transition Metals written by Sittichai Natesakhawat and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Water Gas Shift Reaction by : Panagiotis Smirniotis
Download or read book Water Gas Shift Reaction written by Panagiotis Smirniotis and published by Elsevier. This book was released on 2015-06-11 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water Gas Shift Reaction: Research Developments and Applications outlines the importance of hydrogen as a future fuel, along with the various hydrogen production methods. The book explains the development of catalysts for Water Gas Shift (WGS) reaction at different temperatures and steam/CO ratios, and also discussing the effect of different dopants on the WGS activity of iron oxide and the promotion and inhibition roles of the dopants on the WGS activity of iron oxide are explained. In addition, the book describes extensive characterization of modified ferrite catalysts, especially with Mossbauer spectroscopy and its advantage in understanding properties of metal doped ferrite catalysts, the exact dopant location, and its effect on electron hopping capability and WGS activity of Fe redox couple. - Outlines the importance of the Water Gas Shift Reaction and its application for hydrogen production - Provides detailed information on potential catalysts, their development, and their pros and cons, giving the reader insights on how modified ferrite catalysts work at different temperatures and different steam to CO ratios - Reviews hydrogen technology, its current importance, and production methods - Presents a clear presentation of the topics with many graphics and tables - Offers basic and advanced knowledge of catalysts characterization instrumental techniques
Book Synopsis Rational Design of High Temperature Water-Gas Shift Catalysts with Non-Toxic Earth-Abundant Elements by : Minghui Zhu
Download or read book Rational Design of High Temperature Water-Gas Shift Catalysts with Non-Toxic Earth-Abundant Elements written by Minghui Zhu and published by . This book was released on 2017 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The copper promoted chromium-iron oxide has for decades been used as the commercial catalyst for production of H2 via the High Temperature-Water Gas Shift reaction (HT-WGS). The wide operation temperature range, high activity and robust thermostability has made this catalyst the catalyst of choice for HT-WGS. The toxic nature of hexavalent chromium has motivated extensive research to develop non-chromium HT-WGS catalysts. The lack of fundamental understanding of this HT-WGS catalyst system (catalyst structure under working conditions, reaction mechanism and copper/chromium promotion mechanism), however, have hampered the developed of Cr-free catalysts.
Book Synopsis Investigation of Active Sites and Reaction Networks in Catalytic Hydrogen Production by : Sittichai Natesakhawat
Download or read book Investigation of Active Sites and Reaction Networks in Catalytic Hydrogen Production written by Sittichai Natesakhawat and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Steam reforming (SR) of hydrocarbons and water-gas shift (WGS) are of importance in hydrogen generation technologies due to recent attention focusing on fuel cells. Current research efforts have focused on catalyst development to improve activity, selectivity, and stability under a realistic range of operating conditions. Although coke formation is a major concern for Ni-based catalysts when used for hydrocarbon steam reforming, their low cost and long-proven performance warrants further investigation. Moreover, hydrogen and fuel cell technologies will greatly benefit from innovative high-temperature shift (HTS) catalyst formulations that can overcome some serious drawbacks (i.e., low activity at low temperatures, sintering of magnetite (Fe3O4), a pyrophoric nature, and the harmful effects of Cr6+ on human health). In this Ph. D. study, lanthanide-promoted Ni/Al2O3 catalysts and Fe-based catalysts promoted with first row transition metals were synthesized by a modified sol-gel technique and a coprecipitation method, respectively. The effect of synthesis variables on the catalyst properties (i.e., BET surface area, reducibility, crystallite size, crystal structure, oxidation states, adsorption/desorption behavior, and surface intermediates during the reaction) and, in turn, on the catalytic performance in SR of lower alkanes and the WGS reaction has been investigated. Catalysts were characterized by BET surface area and pore size distribution measurements, temperature-programmed desorption/reduction/oxidation (TPD/TPR/TPO), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), static chemisorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA). The introduction of small amounts (2 wt%) of Ce and Yb in sol-gel Ni/Al2O3 catalysts improves SR activity significantly by enhancing Ni surface area, reducibility of Ni species, and Ni sintering resistance. In addition, the incorporation of Ce in Ni/Al2O3 catalysts results in the reduction of carbon dissolution/diffusion through nickel crystallites, thus preventing catalyst deactivation by coke formation. Formulations of highly active and Cr-free HTS catalysts can be achieved by adding both Al and Cu. The activity of Fe-based catalysts is strongly related to catalyst reducibility, magnetite crystallite size, and redox characteristics. More detailed characterization has provided additional insights into phase transformations, surface intermediates, and reaction/deactivation mechanisms, giving further evidence of the modification of the properties and performance of catalysts through optimized synthesis.
Book Synopsis High Temperature Water Gas Shift Catalysts by : S. Benny
Download or read book High Temperature Water Gas Shift Catalysts written by S. Benny and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The high-temperature (HT) Water Gas Shift (WGS) reaction has considerable technological relevance for lowering CO content during the conversion of natural gas or liquid hydrocarbons to hydrogen. Conventional HT-WGS catalysts based on oxides of iron and chromium are well established industrially. However, it is crucial to remove any impurities present such as Cr6+, S or N during the catalytic process. In particular, Cr6+ is regarded as a Class I carcinogen and its presence is restricted by EU legislation. Even though Cr6+ is reduced during the catalytic process, caution must still be taken to eliminate any further impurities. Hence, it is desirable to identify alternative promoters and develop a Cr-free HT-WGS catalyst. This thesis presents results obtained using atomistic simulation techniques to investigate the effect of Cr3+ and possible alternative dopants in three important iron oxide materials, Hematite ([alpha]-Fe2O3), Maghemite ([gamma]-Fe2O3) and Magnetite (Fe3O4). The starting point is to develop an understanding of the structural properties and distribution of Cr3+ on the bulk and surface material of hematite. The critical stage of understanding the role of Cr3+ provides the basis from which criteria for novel dopants can be assessed. Al3+ and Mn3+ are proposed as the promising candidates on the basis of this study. The research has been extended to other complex iron oxides, such as maghemite and magnetite. In summary, the role of chromium in the HT-WGS reaction has been investigated to establish criteria for effective, alternative promoter dopants. This investigation has provided a detailed insight into the atomic level behaviour of Cr3+, Mn3+, Al3+ impurities in three major iron oxide phases. The alternative dopants predicted in this study have been the subject of parallel experimental studies conducted by Johnson Matthey. The results of this study are already benefiting the design of more efficient iron-oxide catalysts for the HT-WGS reaction.
Book Synopsis Mechanistic Modeling of the High Temperature Water Gas Shift Reaction on Ferrochrome by : John Slocum Coleman
Download or read book Mechanistic Modeling of the High Temperature Water Gas Shift Reaction on Ferrochrome written by John Slocum Coleman and published by . This book was released on 2008 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: ?Pub Inc This dissertation consists of investigations on ferrochrome, copper promoted ferrochrome, and gold on ferrochrome. The first investigation involved the examination of reaction mechanisms for water-gas shift over ferrochrome catalysts under high temperature operation. Mechanisms were developed to represent the two primary mechanism types presented in literature, namely the regenerative and associative mechanisms. Both mechanism types have been suggested within the literature based on the fit of rate expressions derived from them, and experimental characterizations have provided support for both mechanisms. Mechanistic kinetic modeling was performed and comparisons to experimentally available information were made between each of the mechanisms considering both mechanistic parameters and predicted behavior under reaction conditions. A combined mechanism was additionally proposed to provide both mechanistic pathways, and comparisons to each of the individual mechanisms were made. The results of the mechanistic kinetic modeling suggest that an associative mechanism does not accurately describe water-gas shift. Both the regenerative and combined mechanisms yield quantitatively and qualitatively similar predictions. The observations made during the mechanistic kinetic modeling were then used to develop a computational chemistry model of the active site for water-gas shift over ferrochrome. Cluster models representing potential active sites of the (100), (110), and (111) surfaces of magnetite were generated and compared using the enthalpy of localization for the surface oxygen species as a selection criterion. The cluster developed from the (111) surface showed the best qualitative agreement to the regenerative and combined mechanisms, suggesting the (111) surface of magnetite may be catalytically active. The combined mechanism as formulated for the mechanistic kinetic modeling of an unpromoted ferrochrome catalyst was then fit to experimental data generated for a copper promoted ferrochrome catalyst. While copper has been shown in the past to be an effective promoter for ferrochrome water-gas shift catalysts, the method of promotion is still unclear. The mechanistic kinetic study of a copper promoted ferrochrome catalyst suggested that copper acts as a substitutional promoter, modifying key parameters within the mechanistic model. The changes in the kinetic parameters caused by copper in the combined mechanistic model mirror predictions made using a "virtual" catalyst developed from the mechanistic model for an unpromoted ferrochrome. Finally, an experimental study of the preparation and performance of gold promoted low temperature ferrochrome catalysts was underataken. The key to active gold catalysts lies in the size of gold particles supported on the surface of the catalyst. The investigation of nanoparticles preparation techniques and their eventual attachment onto a ferrochrome support suggested that while monodisperse gold can be synthesized, the attachment onto the catalyst surface generates agglomerated clusters that are catalytically inactive. Traditional deposition-precipitation techniques yielded active low temperature catalysts. These catalysts were evaluated kinetically, and a rate expression for low temperature water-gas shift was developed. They were observed to deactivate appreciably under reaction conditions, and this aspect of their performance was also quantified.
Book Synopsis Catalyst Handbook by : Martyn V. Twigg
Download or read book Catalyst Handbook written by Martyn V. Twigg and published by Routledge. This book was released on 2018-12-19 with total page 609 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges the gap between theory and practice. It provides fundamental information on heterogeneous catalysis and the practicalities of the catalysts and processes used in producing ammonia, hydrogen and methanol via hydrocarbon steam reforming. It also covers the oxidation reactions in making formaldehyde from methanol, nitric acid from ammonia and sulphuric acid from sulphur dioxide. Designed for use in the chemical industry and by those in teaching, research and the study of industrial catalysts and catalytic processes. Students will also find this book extremely useful for obtaining practical information not available in more conventional textbooks.
Book Synopsis Plasma Catalysis by : Annemie Bogaerts
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.
Book Synopsis Mössbauer Spectroscopy of Environmental Materials and Their Industrial Utilization by : Enver Murad
Download or read book Mössbauer Spectroscopy of Environmental Materials and Their Industrial Utilization written by Enver Murad and published by Springer Science & Business Media. This book was released on 2011-06-28 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mössbauer Spectroscopy of Environmental Materials and their Industrial Utilization provides a description of the properties of materials formed on the earth's surface, their synthetic analogs where applicable, and the products of their modifications in the course of natural processes, such as weathering, or in industrial processing as reflected in their Mössbauer spectra. Particular emphasis is placed on the way in which these processes can be observed and elucidated through the use of Mössbauer spectroscopy. The first chapter covers the basic theory of the Mössbauer effect and Chapters 2 and 3 deal with the nuts and bolts of experimental Mössbauer spectroscopy. The principles of these first three chapters, illustrated with many case studies, are applied to different areas of interest in Chapters 4 through 12. The book is directed to a broad audience ranging from graduate students in environmental sciences or chemical engineering with little or no expertise in Mössbauer spectroscopy to researchers from other disciplines who are familiar with this technique but wish to learn more about possible applications to environmental materials and issues.
Book Synopsis Modern Developments In Catalysis by : Graham J Hutchings
Download or read book Modern Developments In Catalysis written by Graham J Hutchings and published by World Scientific. This book was released on 2016-11-14 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: The UK Catalysis Hub is a consortium of universities working together on fundamental and applied research to find out how catalysts work and to improve their effectiveness. The contribution of catalysis to manufacturing contributes to almost 40% of global GDP, making development and innovation within the field integral to industry.Modern Developments in Catalysis provides a review of current research and practise on catalysis, focussing on five main themes: catalysis design, environmental catalysis, catalysis and energy, chemical transformation and biocatalysis and biotransformations. Topics range from complex reactions to the intricacies of catalyst preparation for supported nanoparticles, while chapters illustrate the challenges facing catalytic science and the directions in which the field is developing. Edited by leaders of the UK Hub, this book provides insight into one of the most important areas of modern chemistry — it represents a unique learning opportunity for students and professionals studying and working towards speeding-up, improving and increasing the rate of catalytic reactions in science and industry.
Book Synopsis Applications of Mossbauer Spectroscopy by : Richard L. Cohen
Download or read book Applications of Mossbauer Spectroscopy written by Richard L. Cohen and published by Elsevier. This book was released on 2012-12-02 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of Mössbauer Spectroscopy, Volume I is a collection of essays that discusses the research performed using Mössbauer spectroscopy. The book presents the effect of some stabilizers of polyethylene. It demonstrates the polymerization processes and structure of catalytically active centers. The text also describes the chemical processes in butyl rubber vulcanization. It discusses the experimental studies of iron transport proteins and the thermal decomposition of solids. The section that follows describes the paramagnetic hyperfine structure. The book will provide valuable insights for scientists, chemists, students, and researchers in the field of organic chemistry.
Book Synopsis Metal-Support Interaction and Electrochemical Promotion of Nano-Structured Catalysts for the Reverse Water Gas Shift Reaction by : Christopher Panaritis
Download or read book Metal-Support Interaction and Electrochemical Promotion of Nano-Structured Catalysts for the Reverse Water Gas Shift Reaction written by Christopher Panaritis and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The continued release of fossil-fuel derived carbon dioxide (CO2) emissions into our atmosphere led humanity into a climate and ecological crisis. Converting CO2 into valuable chemicals and fuels will replace and diminish the need for fossil fuel-derived products. Through the use of a catalyst, CO2 can be transformed into a commodity chemical by the reverse water gas shift (RWGS) reaction, where CO2 reacts with renewable hydrogen (H2) to form carbon monoxide (CO). CO then acts as the source molecule in the Fischer-Tropsch (FT) synthesis to form a range of hydrocarbons to manufacture chemicals and fuels. While the FT synthesis is a mature process, the conversion of CO2 into CO has yet to be made commercially available due to the constraints associated with high reaction temperature and catalytic stability. Noble metal ruthenium (Ru) has been widely used for the RWGS reaction due to its high catalytic activity, however, several constraints hinder its practical use, associated with its high cost and its susceptibility to deactivation. The doping or bimetallic use of non-noble metals iron (Fe) and cobalt (Co) is an attractive option to lower material cost and tailor the selectivity of the CO2 conversion towards the RWGS reaction without compromising catalytic activity. Furthermore, employing nanostructured catalysts as nanoparticles is a viable solution to further lower the amount of metal used and utilize the highly active surface area of the catalyst. Dispersing nanoparticles on ionically conductive supports/solid electrolytes which contain species like O2−, H+, Na+, and K+, provide an approach to further enhance the reaction. This phenomenon is referred to as metal-support interaction (MSI), allowing for the ions to back spillover from the support and onto the catalyst surface. An in-situ approach referred to as Non-Faradaic Modification of catalytic activity (NEMCA), also known as electrochemical promotion of catalysis (EPOC) is used to in-situ control the movement of ionic species from the solid electrolyte to and away from the catalyst. Both the MSI and EPOC phenomena have been shown to be functionally equivalent, meaning the ionic species act to alter the work function of the catalyst by forming an effective neutral double layer on the surface, which in turn alters the binding energy of the reactant and intermediate species to promote the reaction. The main objective of this work is to develop a catalyst that is highly active and selective to the RWGS reaction at low temperatures (
Book Synopsis Active Site Models for High Temperature Water Gas Shift Reaction Over Iron Oxide Catalysts by : Rainee VanNatter
Download or read book Active Site Models for High Temperature Water Gas Shift Reaction Over Iron Oxide Catalysts written by Rainee VanNatter and published by . This book was released on 2011 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum chemical calculations and microkinetic modeling were carried out to study the water gas shift reaction over iron oxide catalysts. Cluster models corresponding to potential active sites on (100), (110), and (111) surfaces of an Fe3O4 crystal were generated, and the mechanistic thermochemistry of water-gas shift studied by computational chemistry using these model surfaces. At the same time, microkinetic modelling was being used to study various proposed water gas shift mechanisms. These two sets of information were then compared to discriminate between potential reaction mechanisms and catalyst surface structures. Further studies were carried out with copper promoted catalyst clusters in an attempt to see if the clusters would predict the effect of copper on the reaction kinetics.
Book Synopsis An Experimental Investigation of Promoted Iron Based Oxide for High Temperature Water Gas Shift Reaction Catalysts at Membrane Reactor Conditions and an Experimental and Computational Study of Solvent Effects in Toluene Chlorination by : Mang Zhang
Download or read book An Experimental Investigation of Promoted Iron Based Oxide for High Temperature Water Gas Shift Reaction Catalysts at Membrane Reactor Conditions and an Experimental and Computational Study of Solvent Effects in Toluene Chlorination written by Mang Zhang and published by . This book was released on 2003 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis WATER-GAS SHIFT KINETICS OVER IRON OXIDE CATALYSTS AT MEMBRANE REACTOR CONDITIONS. by :
Download or read book WATER-GAS SHIFT KINETICS OVER IRON OXIDE CATALYSTS AT MEMBRANE REACTOR CONDITIONS. written by and published by . This book was released on 2001 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report covers the second year of a project investigating water-gas shift catalysts for use in membrane reactors. It has been established that a simple iron high temperature shift catalyst becomes ineffective in a membrane reactor because the reaction rate is severely inhibited by the build-up of the product CO2. During the past year, an improved microkinetic model for water-gas shift over iron oxide was developed. Its principal advantage over prior models is that it displays the correct asymptotic behavior at all temperatures and pressures as the composition approaches equilibrium. This model has been used to explore whether it might be possible to improve the performance of iron high temperature shift catalysts under conditions of high CO2 partial pressure. The model predicts that weakening the surface oxygen bond strength by less than 5% should lead to higher catalytic activity as well as resistance to rate inhibition at higher CO2 partial pressures. Two promoted iron high temperature shift catalysts were studied. Ceria and copper were each studied as promoters since there were indications in the literature that they might weaken the surface oxygen bond strength. Ceria was found to be ineffective as a promoter, but preliminary results with copper promoted FeCr high temperature shift catalyst show it to be much more resistant to rate inhibition by high levels of CO2. Finally, the performance of sulfided CoMo/Al2O3 catalysts under conditions of high CO2 partial pressure was simulated using an available microkinetic model for water-gas shift over this catalyst. The model suggests that this catalyst might be quite effective in a medium temperature water-gas shift membrane reactor, provided that the membrane was resistant to the H2S that is required in the feed.
Book Synopsis Novel Fe2CrO3 Catalyst for High Temperature Water Gas Shift Reaction by : Yun Lei
Download or read book Novel Fe2CrO3 Catalyst for High Temperature Water Gas Shift Reaction written by Yun Lei and published by . This book was released on 2005 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies of the Water-gas Shift Reaction Over Supported Gold and Platinum Catalysts by : Steven Taylor Evans
Download or read book Studies of the Water-gas Shift Reaction Over Supported Gold and Platinum Catalysts written by Steven Taylor Evans and published by . This book was released on 2004 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
