Download or read book Investigation of Reaction Networks and Active Sites in Ethanol Steam Reforming Reaction Over Ni and Co based Catalysts written by Yeuk Ting Law and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bimetallic catalysts have been widely exploited to improve the performance of various catalytic reactions. Understanding the surface properties and in particular, bimetallic interaction and support effect of the catalytic components is an important step towards rational catalyst design. In this thesis, Ni-Co thin film on polar ZnO single crystal was studied as a model catalyst for ethanol steam reforming reaction. The aim is to provide fundamental understanding of how the surface characteristics of the catalyst influence the mechanism and the efficiency of the reaction. This study focused firstly on the study of the interaction between Ni and Co in oxidative environment using Xray photoelectron spectroscopy (PES). Oxidation of Co is favoured over nickel and the surface is enriched with cobalt oxide. Secondly, Ni-Co thin film supported on polar Zn and O terminated ZnOwas studied by synchrotron based PES. The as deposited layer interacts readily with ZnO and Co is partially oxidized upon deposition, even at room temperature. The interaction of ethanol with Ni- Co/ZnO-Zn was studied by thermal desorption spectroscopy (TDS). Ethanol decomposes in different pathways on Ni and Co, in which C-C bond scission and methane production are favoured on Ni/ZnO-Zn while dehydrogenation is favoured on Co/ZnO-Zn. Finally, Ni-Co powder was studied byin-situ ambient pressure PES under reaction conditions in order to clarify the correspondence between the active state of the catalyst and the reaction activity. The product selectivity on Co catalyst is distinctly different from Ni and Ni-Co. Also, the decomposition of methyl group and the high amount of CO produced over Co is likely to be the cause for its high level of carbon deposition.
Download or read book Investigation of Reaction Networks and Active Sites in Bio ethanol Steam Reforming Over Cobalt Based Catalysts written by Hua Song and published by . This book was released on 2009 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combined with the estimated economic analysis of this process simulated at industrial scale, the outcomes originating from this study will eventually lead to the commercialization of the developed catalyst system specially tailored for central and distributed hydrogen production from steam reforming of bio-derived liquids suitable for fuel cell application.
Download or read book Final Report for Investigation of Reaction Networks and Active Sites in Bio ethanol Steam Reforming Over Co based Catalysts with All Publications Attached written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This was a university-based research project in support of distributed reforming production technologies for hydrogen. Our objective was to examine the steam reforming of bio-ethanol and other related bio-derived liquids over non-precious metal catalyst systems to enable small-scale distributed hydrogen production technologies from renewable sources. The study targeted development of a catalytic system that does not rely on precious metals and that can be active in the 350-550 C temperature range, with high selectivity and high stability. To this end, we adopted a multi-prong research strategy, that included catalyst formulation and synthesis, detailed catalyst characterization, reaction kinetics and reaction engineering, molecular modeling and economic analysis studies. Our approach was an iterative one, where the knowledge gained in one aspect of the study was utilized to modify and fine-tune catalyst development. The research addressed many fundamental and inter-related phenomena involved in the catalytic steam reforming of ethanol that may not be readily studied in an industrial development setting. The outcome of the project was a catalytic system that was able to meet the DOE targets in hydrogen production, with high H2 yield, high selectivity and stability that could perform efficiently in the 350-550 C temperature range. In addition, we were able to answer many fundamental questions about the catalytic systems that could easily be translated to other catalytic systems. The study resulted in 14 refereed journal articles, with one more in preparation. The results were also shared broadly at many different national and international forums such as conferences of the American Chemical Society, American Institute of Chemical Engineers, North American Catalysis Society, International Congress on Catalysis and International Conference on Catalysis for Renewable Sources. There were 30 presentations given at various national and international meetings. The P.I. was also invited to give 11 lectures on the findings from this study at many universities and research centers in the USA and other countries. The knowledge base acquired through this study is expected to bring industry closer to designing catalytic systems that can be tailored for the specific hydrogen production applications, especially for distributed hydrogen production strategies.
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.
Download or read book Ambient Pressure XPS and IRRAS Investigation of Ethanol Steam Reforming on Ni CeO2 111 Catalysts written by and published by . This book was released on 2016 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ambient-Pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Infrared Reflection Absorption Spectroscopy (AP-IRRAS) have been used to elucidate the active sites and mechanistic steps associated with the ethanol steam reforming reaction (ESR) over Ni-CeO2(111) model catalysts. Our results reveal that surface layers of the ceria substrate are both highly reduced and hydroxylated under reaction conditions while the small supported Ni nanoparticles are present as Ni0/NixC. A multifunctional, synergistic role is highlighted in which Ni, CeOx and the interface provide an ensemble effect in the active chemistry that leads to H2. Ni0 is the active phase leading to both C-C and C-H bond cleavage in ethanol and it is also responsible for carbon accumulation. On the other hand, CeOx is important for the deprotonation of ethanol/water to ethoxy and OH intermediates. The active state of CeOx is a Ce3+(OH)x compound that results from extensive reduction by ethanol and the efficient dissociation of water. Additionally, we gain an important insight into the stability and selectivity of the catalyst by its effective water dissociation, where the accumulation of surface carbon can be mitigated by the increased presence of surface OH groups. As a result, the co-existence and cooperative interplay of Ni0 and Ce3+(OH)x through a metal-support interaction facilitate oxygen transfer, activation of ethanol/water as well as the removal of coke.
Download or read book Production of Biofuels and Chemicals with Bifunctional Catalysts written by Zhen Fang and published by Springer. This book was released on 2017-12-27 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides state-of-the-art reviews, current research, prospects and challenges of the production of biofuels and chemicals such as furanic biofuels, biodiesel, carboxylic acids, polyols and others from lignocellulosic biomass, furfurals, syngas and γ-valerolactone with bifunctional catalysts, including catalytic, and combined biological and chemical catalysis processes. The bifunctionality of catalytic materials is a concept of not only using multifunctional solid materials as activators, but also design of materials in such a way that the catalytic materials have synergistic characteristics that promote a cascade of transformations with performance beyond that of mixed mono-functional catalysts. This book is a reference designed for researchers, academicians and industrialists in the area of catalysis, energy, chemical engineering and biomass conversion. Readers will find the wealth of information contained in chapters both useful and essential, for assessing the production and application of various biofuels and chemicals by chemical catalysis and biological techniques.
Download or read book Evaluation and Utilization of Bioethanol Fuels II written by Ozcan Konur and published by CRC Press. This book was released on 2023-12-22 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sixth volume of this handbook provides an overview of the research on the country-based experience of bioethanol fuels at large, Chinese, US, and European experience of bioethanol fuels, production of bioethanol fuel-based biohydrogen fuels for fuel cells, bioethanol fuel cells, and bioethanol fuel-based biochemicals with a collection of 17 chapters. Thus, it complements the fifth volume of this handbook. Hence, the sixth volume indicates that the research on the evaluation and utilization of bioethanol fuels has intensified in recent years to become a major part of the bioenergy and biofuels research together primarily with biodiesel, biohydrogen, and biogas research as a sustainable alternative to crude oil-based gasoline and petrodiesel fuels as well as natural gas and syngas. This book is intended for students, researchers, engineers, policy makers, economist, business managers, and social scientists, working on the production, utilization and evaluation of bioethanol fuels.
Download or read book Mechanistic Studies of Crotonadehyde Partial Hydrogenation and Ethanol Steam Reforming Reactions on Planar Catalysts a Gas phase and Ambient Pressure XPS Study written by Yutichai Mueanngern and published by . This book was released on 2020 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The steam reforming reaction of ethanol to hydrogen gas was investigated on Ni/CeO2 catalysts. Here we show that the morphology of the CeO2 nanocubes-on-Ni can also act as a crucial design parameter—drastically influencing rates of hydrogen production. Controlling the coverage of CeO2 on Ni with LB deposition, reveals a non--monotonic scaling of catalytic rate with Ni--CeO2 interface sites. Hydrogen production rates was found to scale in close proportion to mesoscale interface sites iv formed by aggregates of CeO2 nanoparticles on Ni. It is established that the CeO2 phase of the catalyst helps to dissociate surface hdyroxyls durign reaction doncitions and the Ni phase of the catalyst is a good C--C bond cleavage catalyst forming carbonates and methyl groups at its surface from ethanol udner reactino reaction conditions. Herein we show NAP-XPS correlation of surface hydroxyls across various CeO2 morphologies formed by the self--assembly of CeO2 aggregates on Ni. NAP--XPS shows that the surface is most hydroxylated and at an intermediate coverage where the mesoscale interfaces are enhanced, resulting in the highest hydrogen production rate at that intermediate coverage of CeO2 on Ni. In addition, on these samples where the mesoscale interfaces are maximized, carbon nanotube networks are observed to grow on the order of millimeters from the surface under reaction conditions. Despite m5assive carbon deposition the catalyst remains highly active and shows no deactivation. For the first time, the reversible-nickel catalyzed nanotube growth process under ethanol steam reforming condition is detected in-situ using NAP-XPS. Under steam reforming conditions a carbon shell surrounding a nickel grain opens up, exposing the nickel to catalyze the formation of hydrogen products at the same time continuously catalyzing the elongation of the carbon nanotube network. Whereas in non-steam reforming conditions the nickel recedes underneath a carbon shell and the catalyst is rendered inactive. We propose that the mesoscale interfaces defined by aggregates of CeO2 nanoparticles provide an optimal surface morphology, which allows for efficient surface hydroxyl diffusion from CeO2 sites to Ni domains. The non-deactivation behavior of the Ni under ethanol steam reforming conditions can be explained by the exposed Ni grains, which opens up at the tip of carbon filament structures during steam reforming conditions as show in NAP-XPS measurements.
Download or read book Mechanistic Studies of Alcohol Steam Reforming Catalysts written by Eddie Martono and published by . This book was released on 2013 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanistic Insights of Ethanol Steam Reforming Over Ni CeO X 111 written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the reaction of ethanol and water over Ni-CeO2-x(111) model surfaces to elucidate the mechanistic steps associated with the ethanol steam reforming (ESR) reaction. Our results provide insights about the importance of hydroxyl groups to the ESR reaction over Ni-based catalysts. Systematically, we have investigated the reaction of ethanol on Ni-CeO2-x(111) at varying Ce3 concentrations (CeO1.8-2.0) with absence/presence of water using a combination of soft X-ray photoelectron spectroscopy (sXPS) and temperature-programmed desorption (TPD). Consistent with previous reports, upon annealing, metallic Ni formed on reduced ceria while NiO was the main component on fully oxidized ceria. Ni0 is the active phase leading to both the C-C and C-H cleavage of ethanol but is also responsible for carbon accumulation or coking. We have identified a Ni3C phase that formed prior to the formation of coke. At temperatures above 600K, the lattice oxygen from ceria and the hydroxyl groups from water interact cooperatively in the removal of coke, likely through a strong metal-support interaction between nickel and ceria that facilitates oxygen transfer.
Download or read book Kinetics of Catalytic Reactions written by M. Albert Vannice and published by Springer Science & Business Media. This book was released on 2006-04-09 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes how to conduct kinetic experiments with heterogeneous catalysts, analyze and model the results, and characterize the catalysts Detailed analysis of mass transfer in liquid phase reactions involving porous catalysts. Important to the fine chemicals and pharmaceutical industries so it has appeal to many researchers in both industry and academia (chemical engineering and chemistry departments
Download or read book New Dimensions in Production and Utilization of Hydrogen written by Sonil Nanda and published by Elsevier. This book was released on 2020-08-11 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: The gradual increase of population and the consequential rise in the energy demands in the recent years have led to the overwhelming use of fossil fuels. Hydrogen has recently gained substantial interest because of its outstanding features to be used as clean energy carrier and energy vector. Moreover, hydrogen appears to be an effective alternative to tackle the issues of energy security and greenhouse gas emissions given that it is widely recognized as a clean fuel with high energy capacity. Hydrogen can be produced by various techniques such as thermochemical, hydrothermal, electrochemical, electrolytic, biological and photocatalytic methods as well as hybrid systems. New Dimensions in Production and Utilization of Hydrogen emphasizes on the research, development and innovations in the production and utilization of hydrogen in the industrial biorefining, hydrotreating and hydrogenation technologies, fuel cells, aerospace sector, pharmaceuticals, metallurgy, as well as bio-oil upgrading. Moreover, the supply chain analysis, lifecycle assessment, techno-economic analysis, as well as strengths and threats of global hydrogen market are covered in the book. This book provides many significant insights and scientific findings of key technologies for hydrogen production, storage and emerging applications. The book serves as a reference material for chemical and biochemical engineers, mechanical engineers, physicists, chemists, biologists, biomedical scientists and scholars working in the field of sustainable energy and materials. Discusses the efficient usage of hydrogen as standalone fuel or feedstock in downstream processing Outlines key technologies for hydrogen production and their emerging applications Includes innovative approaches to the research and applications of hydrogen, including hydrotreating technologies, fuel cell vehicles and green fuel synthesis, the aerospace sector, pharmaceuticals, carbon dioxide hydrogenation, and bio-oils upgrading Serves as a reference for chemical, biochemical, and mechanical engineers, physicists, chemists, biologists, and biomedical scientists working in sustainable energy and materials
Download or read book Study of the Effect of Water in Steam Reforming Reaction and Development of a Stable and Active Nickel Based Catalyst written by Md Mahfuzur Rahman and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrogen Production Technologies written by Mehmet Sankir and published by John Wiley & Sons. This book was released on 2017-03-20 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive practical review of the new technologies used to obtain hydrogen more efficiently via catalytic, electrochemical, bio- and photohydrogen production. Hydrogen has been gaining more attention in both transportation and stationary power applications. Fuel cell-powered cars are on the roads and the automotive industry is demanding feasible and efficient technologies to produce hydrogen. The principles and methods described herein lead to reasonable mitigation of the great majority of problems associated with hydrogen production technologies. The chapters in this book are written by distinguished authors who have extensive experience in their fields, and readers will have a chance to compare the fundamental production techniques and learn about the pros and cons of these technologies. The book is organized into three parts. Part I shows the catalytic and electrochemical principles involved in hydrogen production technologies. Part II addresses hydrogen production from electrochemically active bacteria (EAB) by decomposing organic compound into hydrogen in microbial electrolysis cells (MECs). The final part of the book is concerned with photohydrogen generation. Recent developments in the area of semiconductor-based nanomaterials, specifically semiconductor oxides, nitrides and metal free semiconductor-based nanomaterials for photocatalytic hydrogen production are extensively discussed.
Download or read book First principles Study of Ethanol and Methanol Steam Reforming on Co based Materials written by Wenjia Luo and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ethanol steam reforming (ESR) is a promising way to produce hydrogen fuels from bio-renewable sources. Ethanol, as a liquid fuel, is convenient to transport and store. On the other hand, hydrogen is a clean and very efficient fuel if used in Proton Exchange Membrane (PEM) fuel cells. On site or on demand production of hydrogen from bio-ethanol can utilize the advantages of both ethanol and hydrogen fuels. In recent years, Co-based materials were found to be promising ESR catalysts because of their low cost and high efficiency. Ideal ESR catalysts should achieve fast conversion of ethanol, high selectivity to CO2, and long term stability without sintering, coking, or deactivation. Cobalt supported on reducible materials, such as CeO2 and ZnO, were found to have exceptional performance. On these catalyst materials, two oxidation states of Co, Co0 and Co2+, were found to be present. Mechanistic studied suggested that both Co0 and Co2+ have contributions to the catalytic activity of the Co catalyst, although their separate roles are still not clear. his study used a combination of first-principles methods, including density functional theory (DFT), microkinetic modeling, and ab initio thermodynamics, to study the ESR reactions on both the metallic and oxidized cobalt surfaces. Methanol steam reforming (MSR), as a simpler model of ESR, was also studied on the metallic cobalt surfaces. Through DFT calculations, the dominant reaction pathways of ESR and MSR have been identified on metallic and oxidized Co surfaces. The MSR reaction can be considered as a two-stage process, which consists of the methanol decomposition into CO, and the further conversion of CO into CO2 through water-gas shift (WGS) reaction. The ESR can be treated as a three-stage process, which includes ethanol decomposition into CH3 and CO, CH3 oxidation into CO, and CO conversion into CO2 through WGS. It was found that the metallic and oxidized Co phases have quite different catalytic activity in all stages of ESR and MSR. Specifically, the metallic Co has a higher activity in C-C bond breaking steps, but has low activity in carbon oxidation and CO activation. On the contrary, oxidized cobalt shows low activity in C-C bond breaking, but is more facile in carbon oxidation and CO conversion. This study suggests that neither metallic nor oxidized Co is active for all steps of ESR under real reaction conditions. Collaboration between these two oxidation states is likely the reason for the high performance observed in experiments. Such collaboration can potentially happen on the interface between metallic and oxidized Co, where the interactions between these two phases is significant and can produce high ESR catalytic activity. First-principles studies presented in this document can help to clarify the catalytic mechanism of ESR on Co-based materials. Through microkinetic modeling, macroscopic parameters such as turnover frequencies and apparent activation energies can also be predicted and verified by experiments. These results can facilitate the prediction of catalytic activity of Co-based materials based on their structures, and guide the future design of highly active ESR catalysts.
Download or read book Methane Steam Reforming Over Ni based Catalysts written by Fanglin Che and published by . This book was released on 2016 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finally, we provide a 'bottom-up' fundamental insight into two debates regarding methane activation over Ni-based catalysts, including the role of a low concentration of carbon or carbide species and the role of electric fields in a fuel cell system. Our DFT results suggest that inducing a local change of the Ni oxidation states can markedly enhance methane activation. Overall, this thesis will be instructive for the design of heterogeneous reactors with tunable metal oxidation states via the modification of the surface carbon or the interface carbide complex as well as the addition of reaction environment factors (e.g., electric fields).
Download or read book Renewable Hydrogen Technologies written by Luis M Gandia and published by Newnes. This book was released on 2013-05-03 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fields covered by the hydrogen energy topic have grown rapidly, and now it has become clearly multidisciplinary. In addition to production, hydrogen purification and especially storage are key challenges that could limit the use of hydrogen fuel. In this book, the purification of hydrogen with membrane technology and its storage in "solid" form using new hydrides and carbon materials are addressed. Other novelties of this volume include the power conditioning of water electrolyzers, the integration in the electric grid of renewable hydrogen systems and the future role of microreactors and micro-process engineering in hydrogen technology as well as the potential of computational fluid dynamics to hydrogen equipment design and the assessment of safety issues. Finally, and being aware that transportation will likely constitute the first commercial application of hydrogen fuel, two chapters are devoted to the recent advances in hydrogen fuel cells and hydrogen-fueled internal combustion engines for transport vehicles. Hydrogen from water and biomass considered Holistic approach to the topic of renewable hydrogen production Power conditioning of water electrolyzers and integration of renewable hydrogen energy systems considered Subjects not included in previous books on hydrogen energy Micro process technology considered Subject not included in previous books on hydrogen energy Applications of CFD considered Subject not included in previous books on hydrogen energy Fundamental aspects will not be discussed in detail consciously as they are suitably addressed in previous books Emphasis on technological advancements Chapters written by recognized experts Up-to date approach to the subjects and relevant bibliographic references
