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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
In this paper, we investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. Finally, the results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
In this paper, we investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. Finally, the results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.
Author: Publisher: ISBN: Category : Languages : en Pages : 17
Book Description
Ex situ catalytic fast pyrolysis (CFP) is a promising route for producing fungible biofuels; however, this process requires bifunctional catalysts that favor C-O bond cleavage, activate hydrogen at near atmospheric pressure and high temperature (350-500 °C), and are stable under high-steam, low hydrogen-to-carbon environments. Recently, early transition-metal carbides have been reported to selectively cleave C-O bonds of alcohols, aldehydes, and oxygenated aromatics, yet there is limited understanding of the metal carbide surface chemistry under reaction conditions and the identity of the active sites for deoxygenation. In this study, we evaluated molybdenum carbide (Mo2C) for the deoxygenation of acetic acid, an abundant component of biomass pyrolysis vapors, under ex situ CFP conditions, and we probed the Mo2C surface chemistry, identity of the active sites, and deoxygenation pathways using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations.
Author: Anna Rini Sekar Darujati Publisher: ISBN: Category : Catalysts Languages : en Pages : 0
Book Description
The oxidation stability of a low surface area Mo2C catalyst has been studied in the presence of gases associated with the steam and dry (CO2) reforming of methane, at temperatures up to 850°C and pressures to 8 bar. The oxidation onset temperatures were found to be about 600°C when the carbide was exposed to either steam or CO2. There appears to be two distinct mechanisms for Mo2C oxidation: direct oxidation at low temperatures and thermal decomposition followed by oxidation of the Mo metal at temperatures above 750°C. Although onset temperatures were similar, CO2 was a stronger oxidant than steam at the higher temperatures. Both H2 and CO were found to inhibit oxidation and the effect can be explained by their influence on the prevailing kinetics. Trace concentrations of methane were found to completely stabilize the carbide from steam oxidation but significantly higher concentrations were required to stabilize it from CO2 oxidation and this is attributed to the higher rates of CO2 oxidation relative to carburization rates. The effect of pressure on the onset temperature of CO2 oxidation of the carbide was found to be negligible, even when inhibited by CO.
Author: Mark Crocker Publisher: John Wiley & Sons ISBN: 3527344667 Category : Technology & Engineering Languages : en Pages : 634
Book Description
A comprehensive reference to the use of innovative catalysts and processes to turn biomass into value-added chemicals Chemical Catalysts for Biomass Upgrading offers detailed descriptions of catalysts and catalytic processes employed in the synthesis of chemicals and fuels from the most abundant and important biomass types. The contributors?noted experts on the topic?focus on the application of catalysts to the pyrolysis of whole biomass and to the upgrading of bio-oils. The authors discuss catalytic approaches to the processing of biomass-derived oxygenates, as exemplified by sugars, via reactions such as reforming, hydrogenation, oxidation, and condensation reactions. Additionally, the book provides an overview of catalysts for lignin valorization via oxidative and reductive methods and considers the conversion of fats and oils to fuels and terminal olefins by means of esterification/transesterification, hydrodeoxygenation, and decarboxylation/decarbonylation processes. The authors also provide an overview of conversion processes based on terpenes and chitin, two emerging feedstocks with a rich chemistry, and summarize some of the emerging trends in the field. This important book: -Provides a comprehensive review of innovative catalysts, catalytic processes, and catalyst design -Offers a guide to one of the most promising ways to find useful alternatives for fossil fuel resources -Includes information on the most abundant and important types of biomass feedstocks -Examines fields such as catalytic cracking, pyrolysis, depolymerization, and many more Written for catalytic chemists, process engineers, environmental chemists, bioengineers, organic chemists, and polymer chemists, Chemical Catalysts for Biomass Upgrading presents deep insights on the most important aspects of biomass upgrading and their various types.
Author: Robert C. Brown Publisher: John Wiley & Sons ISBN: 1119417570 Category : Science Languages : en Pages : 426
Book Description
A comprehensive examination of the large number of possible pathways for converting biomass into fuels and power through thermochemical processes Bringing together a widely scattered body of information into a single volume, this book provides complete coverage of the many ways that thermochemical processes are used to transform biomass into fuels, chemicals and power. Fully revised and updated, this new edition highlights the substantial progress and recent developments that have been made in this rapidly growing field since publication of the first edition and incorporates up-to-date information in each chapter. Thermochemical Processing of Biomass: Conversion into Fuels, Chemicals and Power, 2nd Edition incorporates two new chapters covering: condensed phased reactions of thermal deconstruction of biomass and life cycle analysis of thermochemical processing systems. It offers a new introductory chapter that provides a more comprehensive overview of thermochemical technologies. The book also features fresh perspectives from new authors covering such evolving areas as solvent liquefaction and hybrid processing. Other chapters cover combustion, gasification, fast pyrolysis, upgrading of syngas and bio-oil to liquid transportation fuels, and the economics of thermochemically producing fuels and power, and more. Features contributions by a distinguished group of European and American researchers offering a broad and unified description of thermochemical processing options for biomass Combines an overview of the current status of thermochemical biomass conversion as well as engineering aspects to appeal to the broadest audience Edited by one of Biofuels Digest’s "Top 100 People" in bioenergy for six consecutive years Thermochemical Processing of Biomass: Conversion into Fuels, Chemicals and Power, 2nd Edition will appeal to all academic researchers, process chemists, and engineers working in the field of biomass conversion to fuels and chemicals. It is also an excellent book for graduate and advanced undergraduate students studying biomass, biofuels, renewable resources, and energy and power generation.
Author: Publisher: ASM International ISBN: 1627080945 Category : Technology & Engineering Languages : en Pages : 426
Book Description
Originally published in 1994, this second edition of Corrosion in the Petrochemical Industry collects peer-reviewed articles written by experts in the field of corrosion that were specifically chosen for this book because of their relevance to the petrochemical industry. This edition expands coverage of the different forms of corrosion, including the effects of metallurgical variables on the corrosion of several alloys. It discusses protection methods, including discussion of corrosion inhibitors and corrosion resistance of aluminum, magnesium, stainless steels, and nickels. It also includes a section devoted specifically to petroleum and petrochemical industry related issues.
Author: Manfred Baerns Publisher: Springer Science & Business Media ISBN: 3662059819 Category : Science Languages : en Pages : 540
Book Description
Written by a team of internationally recognized experts, this book addresses the most important types of catalytic reactions and catalysts as used in industrial practice. Both applied aspects and the essential scientific principles are described. The main topics can be summarized as follows: heterogeneous, homogeneous and biocatalysis, catalyst preparation and characterization, catalytic reaction engineering and kinetics, catalyst deactivation and industrial perspective.
Author: José Luis Pinilla Publisher: MDPI ISBN: 3036510745 Category : Technology & Engineering Languages : en Pages : 134
Book Description
Developing active, selective and energy-efficient heterogeneous catalysts is of paramount importance for the production of high value-added products from energy resources in a more sustainable manner. In this Special Issue of Energies, we provide a showcase of the latest progress in the development of cleaner, more efficient processes for the conversion of these feedstocks into valuable fuels, chemicals and energy. Most of the works collected are focused on the conversion of biomass which clearly reflects the paramount importance that the biorefinery concept will play in the years to come.
Author: Edwin A. Peraza Hernandez Publisher: Springer ISBN: 3319918664 Category : Technology & Engineering Languages : en Pages : 478
Book Description
Origami structures have the ability to be easily fabricated from planar forms, enable the deployment of large structures from small volumes, and are potentially reconfigurable. These characteristics have led to an increased interest in theoretical and computational origami among engineers from across the world. In this book, the principles of origami, active materials, and solid mechanics are combined to present a full theory for origami structures. The focus is on origami structures morphed via active material actuation and formed from sheets of finite thickness. The detailed theoretical derivations and examples make this an ideal book for engineers and advanced students who aim to use origami principles to develop new applications in their field.
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Author: Jon Paul Zbasnik
Author: Anna Rini Sekar Darujati
Author: Mark Crocker
Author: Robert C. Brown
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Author: Manfred Baerns
Author: José Luis Pinilla
Author: Edwin A. Peraza Hernandez