Theoretical Insights Into the Selective Oxidation of Methane to Methanol in Copper-exchanged Mordenite PDF Download
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Languages : en
Pages : 7
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Book Description
Selective oxidation of methane to methanol is one of the most difficult chemical processes to perform. A potential group of catalysts to achieve CH4 partial oxidation are Cu-exchanged zeolites mimicking the active structure of the enzyme methane monooxygenase. However, the details of this conversion, including the structure of the active site, are still under debate. In this contribution, periodic density functional theory (DFT) methods were employed to explore the molecular features of the selective oxidation of methane to methanol catalyzed by Cu-exchanged mordenite (Cu-MOR). We focused on two types of previously suggested active species, CuOCu and CuOOCu. Our calculations indicate that the formation of CuOCu is more feasible than that of CuOOCu. In addition, a much lower C-H dissociation barrier is located on the former active site, indicating that C-H bond activation is easily achieved with CuOCu. We calculated the energy barriers of all elementary steps for the entire process, including catalyst activation, CH4 activation, and CH3OH desorption. Finally, our calculations are in agreement with experimental observations and present the first theoretical study examining the entire process of selective oxidation of methane to methanol.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Selective oxidation of methane to methanol is one of the most difficult chemical processes to perform. A potential group of catalysts to achieve CH4 partial oxidation are Cu-exchanged zeolites mimicking the active structure of the enzyme methane monooxygenase. However, the details of this conversion, including the structure of the active site, are still under debate. In this contribution, periodic density functional theory (DFT) methods were employed to explore the molecular features of the selective oxidation of methane to methanol catalyzed by Cu-exchanged mordenite (Cu-MOR). We focused on two types of previously suggested active species, CuOCu and CuOOCu. Our calculations indicate that the formation of CuOCu is more feasible than that of CuOOCu. In addition, a much lower C-H dissociation barrier is located on the former active site, indicating that C-H bond activation is easily achieved with CuOCu. We calculated the energy barriers of all elementary steps for the entire process, including catalyst activation, CH4 activation, and CH3OH desorption. Finally, our calculations are in agreement with experimental observations and present the first theoretical study examining the entire process of selective oxidation of methane to methanol.
Author: Allegra Latimer
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
While the search for catalysts capable of directly converting methane to higher value commodity chemicals and liquid fuels has been active for over a century, a viable industrial process for selective methane activation has yet to be developed. Generally, this failure has been attributed to two primary difficulties: (1) the high barriers required to activate methane (activity), and (2) the higher activity of the C-H bonds in methanol compared to methane (selectivity). In this thesis, we delve into both of these problems and identify general frameworks and strategies that can be used in future research to identify promising catalyst materials. First, we show that, for the wide range of catalysts that proceed via a radical intermediate, a unifying framework for predicting C-H activation barriers using a single universal descriptor can be established. We combine this scaling approach with a thermodynamic analysis of active site formation to provide a map of methane activation rates, and successfully rationalize the available empirical data across catalyst classes. We then extend this analysis to catalysts that proceeed via a surface-stabilized transition state for methane activation. We present a framework for predicting the transition state's geometry (radical or surface-stabilized) and its approximate energy on a given active site. We then shift our attention to understanding and optimizing selectivity. First, we determine the principles guiding the selectivity of a related reaction, direct methanol to formaldehyde on ruthenium oxide catalysts, and find that limiting electrophilic surface oxygen coverage for this reaction is key to obtaining high selectivity. Next, recognizing that a precise and general quantification of the limitations of catalytic direct methane to methanol has not yet been established, we present a simple kinetic model to explain the selectivity-conversion tradeoff that hampers continuous partial oxidation of methane to methanol. Stemming from this analysis, we suggest several design strategies for increasing methanol yields under the constraint of the selectivity-conversion tradeoff. These strategies include (1) "collectors, " materials with strong methanol adsorption potential that can help to lower the partial pressure of methanol in the gas phase, (2) aqueous reaction conditions, and/or (3) diffusion-limited systems. Having identified these strategies, we work towards realizing a system capitalizing on (2), aqueous reaction conditions, by collaborating with experimental colleagues to develop a low-temperature electrochemical approach for methane oxidation. It is the general aim of this thesis to develop straightforward, accessible models with the help of Density Functional Theory that yield generalizable insights. We are hopeful that the models presented herein may provide a reliable framework for future researchers working to understand and evaluate new catalysts and processes for the direct oxidation of methane to methanol.
Author: Catherine Brookes
Publisher:
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Category :
Languages : en
Pages :
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Author: Vasile I. Parvulescu
Publisher: Elsevier
ISBN: 0444635882
Category : Technology & Engineering
Languages : en
Pages : 388
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Book Description
New Materials for Catalytic Applications proposes the use of both new and existing materials for catalytic applications, such as zeolites, metal oxides, microporous and mesoporous materials, and monocrystals. In addition, metal-oxides are discussed from a new perspective, i.e. nano- and photocatalytic applications. The material presents these concepts with a new focus on strategies in synthesis, synthesis based on a rational design, the correlation between basic properties/potential applications, and new catalytic solutions for acid-base, redox, hydrogenation, photocatalytic reactions, etc. - Presents organometallic concepts for the synthesis of nanocatalysts - Provides a synthesis of new materials following the fluorolytic sol-gel concept - Covers electronic and photocatalytic properties via synthesis of nano-oxide materials - Details the nature of sites in MOFs generating catalytic properties immobilization of triflates in solid matrices for organic reactions
Author: Shikha Gulati
Publisher: Springer Nature
ISBN: 9811679592
Category : Science
Languages : en
Pages : 785
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Book Description
This book highlights the state-of-the-art research and discovery in the use of MOFs in catalysis, highlighting the scope to which these novel materials have been incorporated by the community. It provides an exceptional insight into the strategies for the synthesis and functionalization of MOFs, their use as CO2 and chemical warfare agents capture, their role in bio-catalysis and applications in photocatalysis, asymmetric catalysis, nano-catalysis, etc. This book will also emphasize the challenges with previous signs of progress and way for further research, details relating to the current pioneering technology, and future perspectives with a multidisciplinary approach. Furthermore, it presents up-to-date information on the economics, toxicity, and regulations related to these novel materials.
Author: Annemie Bogaerts
Publisher: MDPI
ISBN: 3038977500
Category : Technology & Engineering
Languages : en
Pages : 248
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Book Description
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.
Author: D.M. Bibby
Publisher: Elsevier
ISBN: 0080960707
Category : Technology & Engineering
Languages : en
Pages : 759
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Book Description
This proceedings volume comprises the invited plenary lectures, contributed and poster papers presented at a symposium organised to mark the successful inauguration of the world's first commercial plant for production of gasoline from natural gas, based on the Mobil methanol-to-gasoline process. The objectives of the Symposium were to present both fundamental research and engineering aspects of the development and commercialization of gas-to-gasoline processes. These include steam reforming, methanol synthesis and methanol-to-gasoline. Possible alternative processes e.g. MOGD, Fischer-Tropsch synthesis of hydrocarbons, and the direct conversion of methane to higher hydrocarbons were also considered.The papers in this volume provide a valuable and extremely wide-ranging overview of current research into the various options for natural gas conversion, giving a detailed description of the gas-to-gasoline process and plant. Together, they represent a unique combination of fundamental surface chemistry catalyst characterization, reaction chemistry and engineering scale-up and commercialization.
Author: Rutger A Van Santen
Publisher: World Scientific
ISBN: 1800614020
Category : Science
Languages : en
Pages : 719
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Book Description
Heterogeneous catalysis has developed over the past two centuries as a technology driven by the needs of society, and is part of Nobel Prize-winning science. This book describes the spectacular increase in molecular understanding of heterogenous catalytic reactions in important industrial processes. Reaction mechanism and kinetics are discussed with a unique focus on their relation with the inorganic chemistry of the catalyst material. An introductory chapter presents the development of catalysis science and catalyst discovery from a historical perspective. Five chapters that form the thrust of the book are organized by type of reaction, reactivity principles, and mechanistic theories, which provide the scientific basis to structure-function relationships of catalyst performance. Present-day challenges to catalysis are sketched in a final chapter. Written by one of the world's leading experts on the topic, this definitive text is an essential reference for students, researchers and engineers working in this multibillion-dollar field.
Author: Martin Bertau
Publisher: Springer Science & Business Media
ISBN: 3642397093
Category : Technology & Engineering
Languages : en
Pages : 699
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Book Description
Methanol - The Chemical and Energy Feedstock of the Future offers a visionary yet unbiased view of methanol technology. Based on the groundbreaking 1986 publication "Methanol" by Friedrich Asinger, this book includes contributions by more than 40 experts from industry and academia. The authors and editors provide a comprehensive exposition of methanol chemistry and technology which is useful for a wide variety of scientists working in chemistry and energy related industries as well as academic researchers and even decision-makers and organisations concerned with the future of chemical and energy feedstocks.
Author: Jens Hagen
Publisher: John Wiley & Sons
ISBN: 3527331654
Category : Technology & Engineering
Languages : en
Pages : 546
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Book Description
Now in it's 3rd Edition, Industrial Catalysis offers all relevant information on catalytic processes in industry, including many recent examples. Perfectly suited for self-study, it is the ideal companion for scientists who want to get into the field or refresh existing knowledge. The updated edition covers the full range of industrial aspects, from catalyst development and testing to process examples and catalyst recycling. The book is characterized by its practical relevance, expressed by a selection of over 40 examples of catalytic processes in industry. In addition, new chapters on catalytic processes with renewable materials and polymerization catalysis have been included. Existing chapters have been carefully revised and supported by new subchapters, for example, on metathesis reactions, refinery processes, petrochemistry and new reactor concepts. "I found the book accesible, readable and interesting - both as a refresher and as an introduction to new topics - and a convenient first reference on current industrial catalytic practise and processes." Excerpt from a book review for the second edition by P. C. H. Mitchell, Applied Organometallic Chemistry (2007)
