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Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Increases in the cost of fossil fuels along with growing concerns for greenhouse gas emissions are prompting the search for renewable sources of liquid fuel and chemicals. Biomass has been considered as the only realistic and sustainable source of renewable organic carbon for the foreseeable future. Heterogeneous catalysis has played an important role in the development of efficient chemical processes to convert biomass to fuels and chemicals. In this respect, the design of inexpensive active and stable heterogeneous catalysts is important to develop new and improved processes for the conversion of biomass. This dissertation focuses on aqueous-phase hydrodeoxygenation (APHDO) and aqueous-phase hydrogenation (APH) as model reactions to design improved supported metal catalysts for the conversion of biomass-derived feedstocks. Both APHDO and APH are crucial in converting biomass-derived compounds into liquid fuels and chemicals. In this dissertation, the activity of a number of monometallic and bimetallic catalysts is compared for APH of carbonyl compounds which is an important reaction in APHDO. Bimetallic Pd-Fe is the most active catalyst among the tested catalysts for APH of C=O and C=C bonds. APHDO of sorbitol was performed with the bimetallic Pd-Fe supported on zirconium phosphate (Zr-P). Zr-P was chosen as the support due to its high Brønsted to Lewis acid ratio and stability in the aqueous phase. The Pd1Fe3/Zr-P catalyst is up to 14 times more active than monometallic Pd/Zr-P and Pt/Zr-P catalysts. Moreover, the Pd1Fe3/Zr-P catalyst produces more C4-C6 products by promoting the conversion of sorbitan and isosorbide and more C1-C3 products by promoting C-C bond cleavage (dehydrogenation/retro-aldol condensation) of sorbitol. Another critical issue of designing heterogeneous catalysts for aqueous-phase reactions is stability of the catalysts. A method for stabilizing base-metal particles of a Co/TiO2 catalyst is developed using atomic layer deposition (ALD) of TiO2 film onto the surface of the Co/TiO2 catalyst. The ALD TiO2 coated Co/TiO2 catalyst was tested for APH reactions in a continuous flow reactor and characterized using chemisorption, surface area analysis, electron microscopy, X-ray diffraction, and small-angle X-ray scattering. Through these techniques, it is shown that the ALD TiO2 coating protects the cobalt particles against leaching and sintering under aqueous conditions. High-temperature treatments of a Co/TiO2 catalyst cause migration of partially reduced TiO2 onto cobalt particles caused by strong metal-support interaction (SMSI) between cobalt and TiO2. The SMSI effect in the Co/TiO2 catalyst is elucidated using in situ Raman spectroscopy and electron microscopy. By the SMSI effect, cobalt particles of the Co/TiO2 catalyst are decorated by TiOx (x 2) species. The TiOx decoration stabilizes the cobalt particles in a similar way to ALD TiO2 overcoating. The SMSI effect also creates a bifunctional catalytic site in the Co/TiO2 which facilitates a furanyl ring-opening reaction. The high-temperature treated Co/TiO2 catalyst had 95 % yield for APH of carbonyl compounds to their corresponding alcohols. The two methods for stabilizing cobalt catalysts introduced in this dissertation, ALD and SMSI, may enable the replacement of expensive novel-metal catalysts with inexpensive base-metal catalysts for aqueous-phase conversion of biomass-derived feedstocks.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Increases in the cost of fossil fuels along with growing concerns for greenhouse gas emissions are prompting the search for renewable sources of liquid fuel and chemicals. Biomass has been considered as the only realistic and sustainable source of renewable organic carbon for the foreseeable future. Heterogeneous catalysis has played an important role in the development of efficient chemical processes to convert biomass to fuels and chemicals. In this respect, the design of inexpensive active and stable heterogeneous catalysts is important to develop new and improved processes for the conversion of biomass. This dissertation focuses on aqueous-phase hydrodeoxygenation (APHDO) and aqueous-phase hydrogenation (APH) as model reactions to design improved supported metal catalysts for the conversion of biomass-derived feedstocks. Both APHDO and APH are crucial in converting biomass-derived compounds into liquid fuels and chemicals. In this dissertation, the activity of a number of monometallic and bimetallic catalysts is compared for APH of carbonyl compounds which is an important reaction in APHDO. Bimetallic Pd-Fe is the most active catalyst among the tested catalysts for APH of C=O and C=C bonds. APHDO of sorbitol was performed with the bimetallic Pd-Fe supported on zirconium phosphate (Zr-P). Zr-P was chosen as the support due to its high Brønsted to Lewis acid ratio and stability in the aqueous phase. The Pd1Fe3/Zr-P catalyst is up to 14 times more active than monometallic Pd/Zr-P and Pt/Zr-P catalysts. Moreover, the Pd1Fe3/Zr-P catalyst produces more C4-C6 products by promoting the conversion of sorbitan and isosorbide and more C1-C3 products by promoting C-C bond cleavage (dehydrogenation/retro-aldol condensation) of sorbitol. Another critical issue of designing heterogeneous catalysts for aqueous-phase reactions is stability of the catalysts. A method for stabilizing base-metal particles of a Co/TiO2 catalyst is developed using atomic layer deposition (ALD) of TiO2 film onto the surface of the Co/TiO2 catalyst. The ALD TiO2 coated Co/TiO2 catalyst was tested for APH reactions in a continuous flow reactor and characterized using chemisorption, surface area analysis, electron microscopy, X-ray diffraction, and small-angle X-ray scattering. Through these techniques, it is shown that the ALD TiO2 coating protects the cobalt particles against leaching and sintering under aqueous conditions. High-temperature treatments of a Co/TiO2 catalyst cause migration of partially reduced TiO2 onto cobalt particles caused by strong metal-support interaction (SMSI) between cobalt and TiO2. The SMSI effect in the Co/TiO2 catalyst is elucidated using in situ Raman spectroscopy and electron microscopy. By the SMSI effect, cobalt particles of the Co/TiO2 catalyst are decorated by TiOx (x 2) species. The TiOx decoration stabilizes the cobalt particles in a similar way to ALD TiO2 overcoating. The SMSI effect also creates a bifunctional catalytic site in the Co/TiO2 which facilitates a furanyl ring-opening reaction. The high-temperature treated Co/TiO2 catalyst had 95 % yield for APH of carbonyl compounds to their corresponding alcohols. The two methods for stabilizing cobalt catalysts introduced in this dissertation, ALD and SMSI, may enable the replacement of expensive novel-metal catalysts with inexpensive base-metal catalysts for aqueous-phase conversion of biomass-derived feedstocks.
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: Feng-Shou Xiao Publisher: John Wiley & Sons ISBN: 1119128099 Category : Science Languages : en Pages : 336
Book Description
A comprehensive introduction to the design, synthesis, characterization, and catalytic properties of nanoporous catalysts for the biomass conversion With the specter of peak oil demand looming on the horizon, and mounting concerns over the environmental impact of greenhouse gas emissions, biomass has taken on a prominent role as a sustainable alternative fuel source. One critical aspect of the biomass challenge is the development of novel catalytic materials for effective and controllable biomass conversion. Edited by two scientists recognized internationally for their pioneering work in the field, this book focuses on nanoporous catalysts, the most promising class of catalytic materials for the conversion of biomass into fuel and other products. Although various catalysts have been used in the conversion of biomass-derived feedstocks, nanoporous catalysts exhibit high catalytic activities and/or unique product selectivities due to their large surface area, open nanopores, and highly dispersed active sites. This book covers an array of nanoporous catalysts currently in use for biomass conversion, including resins, metal oxides, carbons, mesoporous silicates, polydivinylbenzene, and zeolites. The authors summarize the design, synthesis, characterization and catalytic properties of these nanoporous catalysts for biomass conversions, discussing the features of these catalysts and considering future opportunities for developing more efficient catalysts. Topics covered include: Resins for biomass conversion Supported metal oxides/sulfides for biomass oxidation and hydrogenation Nanoporous metal oxides Ordered mesoporous silica-based catalysts Sulfonated carbon catalysts Porous polydivinylbenzene Aluminosilicate zeolites for bio-oil upgrading Rice straw Hydrogenation for sugar conversion Lignin depolymerization Timely, authoritative, and comprehensive, Nanoporous Catalysts for Biomass Conversion is a valuable working resource for academic researchers, industrial scientists and graduate students working in the fields of biomass conversion, catalysis, materials science, green and sustainable chemistry, and chemical/process engineering.
Author: Publisher: ISBN: Category : Languages : en Pages : 18
Book Description
Deoxygenation is an important reaction in the conversion of biomass-derived oxygenates to fuels and chemicals. A key route for biomass refining involves the production of pyrolysis oil through rapid heating of the raw biomass feedstock. Pyrolysis oil as produced is highly oxygenated, so the feasibility of this approach depends in large part on the ability to selectively deoxygenate pyrolysis oil components to create a stream of high-value finished products. Identification of catalytic materials that are active and selective for deoxygenation of pyrolysis oil components has therefore represented a major research area. One catalyst is rarely capable of performing the different types of elementary reaction steps required to deoxygenate biomass-derived compounds. For this reason, considerable attention has been placed on bifunctional catalysts, where two different active materials are used to provide catalytic sites for diverse reaction steps. Here, we review recent trends in the development of catalysts, with a focus on catalysts for which a bifunctional effect has been proposed. We summarize recent studies of hydrodeoxygenation (HDO) of pyrolysis oil and model compounds for a range of materials, including supported metal and bimetallic catalysts as well as transition-metal oxides, sulfides, carbides, nitrides, and phosphides. Particular emphasis is placed on how catalyst structure can be related to performance via molecular-level mechanisms. Finally, these studies demonstrate the importance of catalyst bifunctionality, with each class of materials requiring hydrogenation and C-O scission sites to perform HDO at reasonable rates.
Author: Publisher: ISBN: Category : Languages : en Pages : 28
Book Description
The main objective of our research has been to elucidate fundamental concepts associated with controlling the activity, selectivity, and stability of bifunctional, metal-based heterogeneous catalysts for tandem reactions, such as liquid-phase conversion of oxygenated hydrocarbons derived from biomass. We have shown that bimetallic catalysts that combine a highly-reducible metal (e.g., platinum) with an oxygen-containing metal promoter (e.g., molybdenum) are promising materials for conversion of oxygenated hydrocarbons because of their high activity for selective cleavage for carbon-oxygen bonds. We have developed methods to stabilize metal nanoparticles against leaching and sintering under liquid-phase reaction conditions by using atomic layer deposition (ALD) to apply oxide overcoat layers. We have used controlled surface reactions to produce bimetallic catalysts with controlled particle size and controlled composition, with an important application being the selective conversion of biomass-derived molecules. The synthesis of catalysts by traditional methods may produce a wide distribution of metal particle sizes and compositions; and thus, results from spectroscopic and reactions kinetics measurements have contributions from a distribution of active sites, making it difficult to assess how the size and composition of the metal particles affect the nature of the surface, the active sites, and the catalytic behavior. Thus, we have developed methods to synthesize bimetallic nanoparticles with controlled particle size and controlled composition to achieve an effective link between characterization and reactivity, and between theory and experiment. We have also used ALD to modify supported metal catalysts by addition of promoters with atomic-level precision, to produce new bifunctional sites for selective catalytic transformations. We have used a variety of techniques to characterize the metal nanoparticles in our catalysts, including scanning transmission electron microcopy (STEM) to measure size and structure, energy dispersive X-ray spectroscopy (EDS) to measure atomic composition, X-ray absorption spectroscopy (XAS) to measure oxidation state and metal coordination, Fourier transform infrared spectroscopy (FTIR) to study adsorbed species, laser Raman spectroscopy to probe metal oxide promoters, and temperature programmed reaction/desorption to study the energetics of adsorption and desorption processes. We have studied our bimetallic catalysts for the selective cleavage of carbon-oxygen bonds, and we have studied the effects of adding metal oxide promoters to supported platinum and gold catalysts for water-gas shift (i.e., the production of hydrogen by reaction of carbon monoxide with water). We anticipate that the knowledge obtained from our studies will allow us to identify promising directions for new catalysts that show high activity, selectivity, and stability for important reactions, such as the conversion of biomass-derived oxygenated hydrocarbons to fuels and chemicals.
Author: A. V. Bridgwater Publisher: Cpl Press ISBN: Category : Science Languages : en Pages : 208
Book Description
This edited and updated version of the final report of the IEA Bioenergy Pyrolysis Task, is useful both to newcomers to the subject area and those already involved in research, development, and implementation.
Author: Davide Ravelli Publisher: John Wiley & Sons ISBN: 3527825037 Category : Science Languages : en Pages : 434
Book Description
Explore the potential of biomass-based chemicals with this comprehensive new reference from leading voices in the field With the depletion of fossil raw materials a readily ascertainable inevitability, the exploitation of biomass-based renewable derivatives becomes ever more practical and realistic. In Biomass Valorization: Sustainable Methods for the Production of Chemicals, accomplished researchers and authors Davide Ravelli and Chiara Samori deliver a thorough compilation of state-of-the-art techniques and most advanced strategies used to convert biomass into useful building blocks and commodity chemicals. Each chapter in this collection of insightful papers begins by detailing the core components of the described technology, along with a fulsome description of its advantages and limitations, before moving on to a discussion of recent advancements in the field. The discussions are grouped by the processed biomass, such as terrestrial biomass, aquatic biomass, and biomass-deriving waste. Readers will also benefit from the inclusion of: A thorough introduction to the role of biomass in the production of chemicals An exploration of biomass processing via acid, base and metal catalysis, as well as biocatalysis A practical discussion of biomass processing via pyrolysis and thermochemical-biological hybrid processes A concise treatment of biomass processing assisted by ultrasound and via electrochemical, photochemical and mechanochemical means Perfect for chemical engineers, catalytic chemists, biotechnologists, and polymer chemists, Biomass Valorization: Sustainable Methods for the Production of Chemicals will also earn a place in the libraries of environmental chemists and professionals working with organometallics and natural products chemists.
Author: Marcel Schlaf Publisher: Springer ISBN: 981287769X Category : Technology & Engineering Languages : en Pages : 206
Book Description
Volume II presents the latest advances in catalytic hydrodeoxygenation and other transformations of some cellulosic platform chemicals to high value-added products. It presents the theoretical evaluation of the energetics and catalytic species involved in potential pathways of catalyzed carbohydrate conversion, pathways leading to the formation of humin-based by-products, and thermal pathways in deriving chemicals from lignin pyrolysis and hydrodeoxygenation. Catalytic gasification of biomass under extreme thermal conditions as an extension of pyrolysis is also discussed. Marcel Schlaf, PhD, is a Professor at the Department of Chemistry, University of Guelph, Canada. Z. Conrad Zhang, PhD, is a Professor at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, China.
Author: John Regalbuto Publisher: CRC Press ISBN: 1420006509 Category : Science Languages : en Pages : 490
Book Description
This text explores the optimization of catalytic materials through traditional and novel methods of catalyst preparation, characterization, and monitoring for oxides, supported metals, zeolites, and heteropolyacids. It focuses on the synthesis of bulk materials and of heterogeneous materials, particularly at the nanoscale. The final chapters examine pretreatment, drying, finishing effects, and future applications involving catalyst preparation and the technological advances necessary for continued progress. Topics also include heat and mass transfer limitations, computation methods for predicting properties, and catalyst monitoring on laboratory and industrial scales.
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Author: Surapas Sitthisa
Author: Mark Crocker
Author: Feng-Shou Xiao
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Author: A. V. Bridgwater
Author: Davide Ravelli
Author: Marcel Schlaf
Author: John Regalbuto