Download or read book Conversion of Oxygenates from Biomass derived Compounds Over Supported Metal Catalysts written by Surapas Sitthisa and published by . This book was released on 2012 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design of Supported Metal Catalysts for Aqueous phase Conversion of Biomass derived Oxygenates written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Nanoporous Catalysts for Biomass Conversion written by Feng-Shou Xiao and published by John Wiley & Sons. This book was released on 2017-09-07 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Bifunctional Catalysts for Upgrading of Biomass derived Oxygenates written by and published by . This book was released on 2016 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Biomass Processing over Gold Catalysts written by Olga A. Simakova and published by Springer Science & Business Media. This book was released on 2013-07-13 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book describes the valorization of biomass-derived compounds over gold catalysts. Since biomass is a rich renewable feedstock for diverse platform molecules, including those currently derived from petroleum, the interest in various transformation routes has become intense. Catalytic conversion of biomass is one of the main approaches to improving the economic viability of biorefineries. In addition, Gold catalysts were found to have outstanding activity and selectivity in many key reactions. This book collects information about transformations of the most promising and important compounds derived from cellulose, hemicelluloses, and woody biomass extractives. Since gold catalysts possess high stability under oxidative conditions, selective oxidation reactions were discussed more thoroughly than other critical reactions such as partial hydrogenation, acetalization, and isomerization. The influence of reaction conditions, the role of the catalyst, and the advantages and disadvantages of using gold are presented for all of the reactions mentioned above. This book provides an overview of the recent research results focusing on application of gold catalysts for synthesis of valuable chemicals using renewable feedstocks.

Download or read book Chemical Catalysts for Biomass Upgrading written by Mark Crocker and published by John Wiley & Sons. This book was released on 2020-03-09 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Fundamental Studies of the Reforming of Oxygenated Compounds Over Supported Metal Catalysts written by and published by . This book was released on 2016 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Catalytic Conversion of Biomass derived Compounds to Fuels and Chemicals written by Ron Christopher Runnebaum and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the potential routes for production of fuels and chemicals from lignocellulosic biomass, fast pyrolysis accompanied by or followed by catalytic upgrading offers excellent potential because the number of conversion steps is small and the processing may be cost effective. Lignin-derived bio-oils can be converted into fuels and aromatic chemicals, with a key processing challenge being the removal of oxygen. The literature of bio-oils conversion is largely lacking in fundamental chemistry, which limits the usefulness of the available data for predicting catalyst performance. To determine a quantitative reaction network, we designed and constructed four identical tubular flow reactor systems with flexibility to produce data at high and at low conversions and with ability to identify and quantify even trace products by GC-MS and GC-FID. Higher conversion data are necessary to determine trace products formed in the conversions of the individual reactants and enable reaction networks that are more detailed than any previously published to be elucidated. Low conversion data are required to determine quantitative kinetics of reactions that lead to the most abundant products. These reactor systems also enabled mass balance closures of greater than 95%. Reaction networks were elucidated to account for the reactions of a group of compounds prototypical of lignin and compounds derived from it, incorporating the representative functional groups, such as aromatic rings and ether linkages--the compounds are anisole, 4-methylanisole, and furan. These reactants are converted in the presence of catalysts representative of important catalyst classes, including solid acid (HY zeolite), supported metal (platinum on [gamma]-Al2O3, Pt/[gamma]-Al2O3), and bifunctional (platinum of SiO2-Al2O3, Pt/SiO2-Al2O3) catalysts. The results show that one of the dominant classes of reactions observed with anisole and 4-methylanisole is transalkylation. When the catalyst was HY zeolite, transalkylation was the only kinetically significant reaction class. Hydrogenation, dehydrogenation, hydrogenolysis (C--O bond cleavage reactions that did not remove oxygen from the organic reactant), and hydrodeoxygenation (C--O bond cleavage reactions that removed oxygen from the organic reactant) were also observed in the conversion of each reactant (anisole, 4-methylanisole, and furan) with the supported-platinum catalysts. The data determine quantitative conversions and selectivities of the products that were formed in relatively high yields at conversions

Download or read book Catalysis for Clean Energy and Environmental Sustainability written by K. K. Pant and published by Springer Nature. This book was released on 2021-05-13 with total page 933 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is part of a two-volume work that offers a unique blend of information on realistic evaluations of catalyst-based synthesis processes using green chemistry principles and the environmental sustainability applications of such processes for biomass conversion, refining, and petrochemical production. The volumes provide a comprehensive resource of state-of-the-art technologies and green chemistry methodologies from researchers, academics, and chemical and manufacturing industrial scientists. The work will be of interest to professors, researchers, and practitioners in clean energy catalysis, green chemistry, chemical engineering and manufacturing, and environmental sustainability. This volume focuses on the potentials, recent advances, and future prospects of catalysis for biomass conversion and value-added chemicals production via green catalytic routes. Readers are presented with a mechanistic framework assessing the development of product selective catalytic processes for biomass and biomass-derived feedstock conversion. The book offers a unique combination of contributions from experts working on both lab-scale and industrial catalytic processes and provides insight into the use of various catalytic materials (e.g., mineral acids, heteropolyacid, metal catalysts, zeolites, metal oxides) for clean energy production and environmental sustainability.

Download or read book Catalytic Conversion of Lignin derived Compounds to Fuels and Chemicals written by Tarit Nimmanwudipong and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The environmental problems caused by the production and usage of non-renewable fossil fuels has encouraged scientists to conduct research on alternative fuels. Lignocellolusic biomass is considered one of the most promising resources of alternative liquid fuels as well as renewable chemicals. Among several potential routes for biomass conversion, fast pyrolysis and subsequent catalytic upgrading has gained interest widely. Although the combination involves minimum numbers of steps, the cost of resultant fuels and chemicals is not yet low. Therefore, research is needed for better understanding of the process. This study considered the potential use of "bio-oils", product from fast pyrolysis of lignin, the under-utilized part of lignocellulose, as possible aromatic chemical and fuel feedstock source with the key challenge being the removal of excessive oxygen. The literature of catalytic upgrading of lignin-derived bio-oils is still lacking fundamental chemistry. Detailed and quantitative information about the products, the important reaction pathways, and kinetics is limited, but vital as basis for predicting catalyst choices and designing processes. Thus, our goal was to provide such information and to begin unraveling the chemistry of conversion of oxygenate molecules characteristic of lignin-derived bio-oils--and specifically to understand crucial catalytic oxygen-removal reactions. We investigated the conversion of prototypical compounds that represent important components in lignin-derived bio-oils. The reactions were catalyzed by a solid acid (HY zeolite) and supported metals (Pt/[gamma]-Al2O3), which are typical in petroleum and petrochemical industries. This dissertation addresses catalytic reactions of guaiacol, cyclohexanone, and eugenol. For the first time in this field, our data determine quantitative conversion, selectivity of the products, and approximate kinetics of the primary products in the reactions with Pt/[gamma]-Al2O3. The results show that four major reaction classes including transalkylation, hydrogenation, hydrogenolysis, and hydrodeoxygenation were dominant. Without H2 as a reactant and a metal function in the catalyst, transalkylation was the only important reaction class as observed in the conversion catalyzed by acidic HY zeolite. Higher H2 partial pressure led to higher selectivity of oxygen removal products in the conversion catalyzed by Pt/[gamma]-Al2O3. The data identify the role of catalyst functions and imply that a supported-metal catalyst and high pressure H2 will be necessary for oxygen removal of compounds found in lignin-derived bio-oils. Catalyst deactivation was usually observed in the conversion with HY zeolite and Pt/[gamma]-Al2O3. The earlier results indicate that acid sites of the catalysts were associated with the formation of carbonaceous materials on those catalysts. Therefore, the conversion of guaiacol catalyzed by basic supported platinum (Pt/MgO) was investigated. The data show that Pt/MgO deactivated less rapidly compared to other catalysts. The corresponding selectivity to oxygen removal products was nearly doubled the value observed from the reactions catalyzed by Pt/[gamma]-Al2O3, demonstrating potential value of basic support for selective HDO process. In summary, results obtained from this research lead to better understanding of catalytic conversion of lignin-derived compounds. Extrapolation of these understanding will help predicting catalyst performance in the upgrading of bio-oils and ultimately designing suitable catalysts and optimizing operating conditions for the conversion of lignin to fuels and chemicals.

Download or read book Reaction and Characterization Studies of the Conversion of Biomass derived Carbohydrates on Supported Metal Catalysts written by Edward Leonidovich Kunkes and published by . This book was released on 2009 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalytic Conversion of Biomass derived Compounds Into Specialty Chemicals and Diesel Fuel Precursor Molecules written by Paolo Andres Cuello Penaloza and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomass offers a plethora of opportunities to obtain useful and unique products in a sustainable way, be it chemicals with specialty applications, or molecules that can be blended into our everyday fuels, potentially improving their desired properties. In this work, we study two processes involving the conversion of biomass-derived feedstocks into specialty chemicals and diesel fuel precursors using suitable solid catalysts for each application. In Chapters 2 and 3, we delve into the production of hexane-1,2,5,6-tetrol from levoglucosanol, which is ultimately obtained from a cellulose direct derivate, and a potential application as a polymer precursor. In Chapter 2, we obtain kinetic information for the conversion of levoglucosanol into the polyol using a Pt-WOx/TiO2 catalyst at industrially relevant concentrations (10 - 30wt% reactant in water), showing that with this catalyst we can obtain selectively our product of interests, and also preserve over 90% of the reactant stereocenters. We also demonstrate the relative stability of this catalyst compared to what is known in literature, and its regenerability as well. In Chapter 3, we show a potential application for hexane-1,2,5,6-tetrol in the synthesis of tetrol-boronate copolymers when benzenediboronic acids are used. We prove that a facile synthesis is possible at room temperature with various solvents, and demonstrate that the properties of the polymers are impacted by the choice of a solvent, and the diastereomeric excess of the reactant, managing to obtain a first-known case of a chiral polymer when 98% d.e. (S,R)-hexane-1,2,5,6-tetrol is used. In Chapters 4 and 5, we study the selective conversion of ethanol into larger molecules that can be ultimately converted into compounds that can be blended into diesel by different methods when MgAl mixed metal oxide catalysts that have very low loadings of Cu are used. In Chapter 4, we demonstrate that when Cu loadings less than 0.6wt% are used in MgAl catalysts, very high diesel fuel precursor selectivities may be obtained, with the most significant products being larger alcohols and aldehydes, followed by large esters, and relatively minor amounts of ethyl acetate. We proved that changing the properties of the MgAl support does not greatly impact the performance of the catalyst, instead we found that the loading of Cu is the determinant factor in catalyst performance due to Cu acting more as a promoter of MgAl acid-base chemistry than as an actual catalyst for the Guerbet coupling reaction. The presence of Cu in low amounts also enables the selective production of esters with 6 or more carbons over ethyl acetate. The studied catalysts also promoted high product alcohol linearity, and the alcohol selectivity per carbon number fitted the Schultz-Flory distribution, showing that alcohol growth is dictated by chain growth behavior. In Chapter 5, we studied the performance of a single low Cu loading MgAl catalyst at different contact times, performed tests at varying ethanol-to-hydrogen partial pressure ratios, and performed cofeed studied of ethanol with acetaldehyde and ethyl acetate in order to elucidate the reaction network of ethanol oligomerization to larger oxygenates. We found that selectivity to higher alcohols was greater towards alcohols at all conversions, and alcohols exhibit chain-growth at all contact times. We found that ester and ketone selectivity increase with conversion, with their sizes becoming larger with conversion as well. Esters are series products from alcohols and aldehydes. Finally, we demonstrated that higher linear alcohols will be more selective to esters that ethanol, and that branched alcohols feeds may form esters selectively. Finally, in Chapter 6, we cover the conclusions from all the performed studies, and provide an outlook on future research avenues that enable the effective conversion of biomass-derived feedstocks into products of added value using solid catalysts.

Download or read book Kinetics of Catalytic Upgrading Reactions of Biomass derived and Model Oxygenates written by Benginur Demir and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lignocellulosic biomass, as a renewable carbon-neutral resource, can be utilized to sustainably produce versatile chemicals and fuels while eliminating the environmental issues caused by unrestrained use of fossil fuels. Fundamental understanding of reaction mechanisms and kinetics for many catalytic transformations of biomass-derived compounds is required to synthesize a variety of chemical intermediates in the fine chemical, polymer and pharmaceutical industries. This dissertation focuses on the kinetics of catalytic upgrading reactions of biomass-derived and model oxygenates using a combined approach including experimental, characterization and computational methods to design rational solvent systems, novel catalysts and efficient reactors for biorefineries. Chapter 3 and Chapter 4 discuss the fundamentals of catalytic upgrading of biomass-derived carbohydrates, which have high content of oxygenated functional groups. In Chapter 3, we show that the use of polar aprotic solvents in acid-catalyzed biomass conversion reactions such as fructose dehydration to hydroxymethylfurfural leads to improved reaction rates and product selectivities. In Chapter 4, we illustrate that further increases in catalyst performance in polar aprotic solvents can be achieved through the addition of inorganic salts, specifically chlorides, which was explained by the initial and transition state contributions to solvation effects. In Chapter 5 and Chapter 6, we discuss metal-catalyzed hydrogenation of biomass-derived chemicals employing kinetic studies with a model oxygenate. Chapter 5 reports that platinum displays a self-adjusting surface that is active for the hydrogenation of acetone over a wide range of reaction conditions investigated by reaction kinetics measurements under steady-state and transient conditions, electronic structure calculations employing density-functional theory, and microkinetic modeling with Bragg-Williams and Langmuir approximations. Chapter 6 outlines the promotional effects of water addition on the rates of acetone hydrogenation over oxophilic metal catalysts. Chapter 7 and Chapter 8 present the sustainable valorization of lignin streams to propose a depolymerization technique of lignin that can be combined with a current polysaccharide-centric biorefinery process. Chapter 7 focuses on the kinetics and mechanistic studies on lignin hydrogenolysis on Pd/C to continuously manufacture near-theoretical yields of phenolic platform monomers in a flow-through system. Chapter 8 expands upon the process development on continuous lignin hydrogenolysis and provides insights on the reactivity and selectivity of bimetallic catalysts consisting of an easily-reducible metal (i.e., Pt and Pd) and an oxophilic promoter (i.e., Co and Ag) using [beta]-ether lignin model compounds. Finally, this dissertation is concluded with suggestions for future directions.

Download or read book Reaction Pathways and Mechanisms in Thermocatalytic Biomass Conversion II written by Marcel Schlaf and published by Springer. This book was released on 2015-10-30 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Conversion of Biomass derived Oxygenated Compounds to Hydrocarbon Fuels and Commodity Chemicals Using Solid Acid Catalysts written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the inevitable depletion of fossil fuel reserves, the development and utilization of renewable resources carry tremendous strategic significance in sustaining society's ever-growing needs for energy and materials in the long run. Amongst all forms of renewable energy resources, biomass assumes the unique position of being the only renewable source of carbon, from which liquid transportation fuels and organic chemicals are produced. The present thesis studies the catalytic conversion of key oxygenated platform molecules derived from the cellulose fraction of lignocellulosic biomass using solid acid catalysts to produce hydrocarbon fuels and commodity chemicals. A catalytic route was first developed to convert an aqueous stream of gamma-valerolactone (GVL) over two solid acid catalysts into liquid alkenes with potential application as jet or diesel fuel precursors. In this process, GVL was nearly quantitatively decarboxylated into a stream of butene, which allowed for the use of well-established olefin oligomerization chemistry to produce C8+ hydrocarbons with overall yields over 60%. Kinetic studies on the inter-conversion between GVL and pentenoic acids and their decarboxylation led to the development of a computerized model that satisfactorily captures experimental trends and thus can serve as a useful tool in reactor design and process optimization. Experimental evidences obtained at short space times revealed that 1-butene was the primary decarboyxlation product. Based on this observation, solid Lewis acid catalysts were used to achieve selective production of 1-butene via GVL decarboxylation by effectively suppressing isomerization of the terminal olefin. Alternatively, GVL was converted into pentanoic acid by consecutive ring opening and hydrogenation over a bifunctional palladium-niobia catalyst. Pentanoic acid was further upgraded via ketonization reaction to form nonanone for use as diesel precursors. Therein, commercial niobia was found to crystallize and lose its surface area under hydrothermal conditions. Two niobia-silica composite materials were synthesized which showed significant improvement in hydrothermal stability. Finally, a highly selective process was developed to convert furanics, including 2,5-dimethylfuran, 2-methylfuran and furan into p-xylene, toluene and benzene, respectively, through Diels-Alder type cycloaddition with ethylene followed by dehydration. Tungstated zirconia was identified as a highly efficient catalyst for this reaction due to its high Brønsted acidity.

Download or read book Catalytic Processes for The Valorisation of Biomass Derived Molecules written by Francesco Mauriello and published by MDPI. This book was released on 2019-11-22 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decades, inedible lignocellulosic biomasses have attracted significant attention for being abundant resources that are not in competition with agricultural land or food production and, therefore, can be used as starting renewable material for the production of a wide variety of platform chemicals. The three main components of lignocellulosic biomasses are cellulose, hemicellulose and lignin, complex biopolymers that can be converted into a pool of platform molecules including sugars, polyols, alchols, ketons, ethers, acids and aromatics. Various technologies have been explored for their one-pot conversion into chemicals, fuels and materials. However, in order to develop new catalytic processes for the selective production of desired products, a complete understanding of the molecular aspects of the basic chemistry and reactivity of biomass derived molecules is still crucial. This Special Issue reports on recent progress and advances in the catalytic valorization of cellulose, hemicellulose and lignin model molecules promoted by novel heterogeneous systems for the production of energy, fuels and chemicals.

Download or read book Controlling Reactivity in the Conversion of Biomass derived Levoglucosenone to Renewable Chemicals Over Metal and Acid Catalysts written by Siddarth Hari Krishna and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have investigated the catalytic conversion of biomass-derived intermediates to a variety of renewable chemicals over metal and acid catalysts, with an emphasis on the platform molecule levoglucosenone. Lignocellulosic biomass and sugars are sustainable sources of carbon which can be converted, through selective C-O cleavage and hydrogenation reactions, to precursors to high-value chemicals such as polymers and non-toxic solvents. Metal catalysts facilitate hydrogenation of C=C and C=O bonds; acid catalysts facilitate C-O cleavage reactions; and bifunctional metal-acid catalysts facilitate these reactions in tandem. As biomass-derived feedstocks are highly functionalized, controlling the selectivity to desired products is a critical component of economically viable conversion processes. Reaction pathways were elucidated using a combination of techniques including analysis of products formed over time, variation of reaction conditions, variation of active site properties, investigation of stereochemistry, and isotopic labeling. Reactions studied include the acid-catalyzed isomerization of levoglucosenone to 5-hydroxymethylfurfural; the metal-catalyzed hydrogenation to Cyrene and levoglucosanol; hydrogenolysis of levoglucosanol to tetrahydrofurandimethanol; hydrogenolysis of levoglucosanol to 1,2,5,6-hexanetetrol; and conversion of methyl glycosides to hexane-tetrols and hexane-triols. We demonstrated how a fundamental understanding of the catalytic chemistry leads to the ability to tune selectivity towards desired products, thereby providing directions for the rational design of processes to produce valuable chemicals from biomass.