Download or read book Iron modified mesoporous silica as efficient heterogeneous lewis acid catalysts written by Wan Xu and published by . This book was released on 2018 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les catalyseurs hétérogènes acides de Lewis ont principalement attiré beaucoup d'attention à cause de leurs applications dans de nombreux processus chimiques tels que le raffinage de pétrole. De plus, la facilité de séparer avec la phase liquide, et peu de déchets dangereux générés dans les processus répondent aux exigences de la chimie verte. Par conséquent, il est nécessaire de concevoir les catalyseurs acides de Lewis de façon simple, efficace, et peu couteux. Pour ce faire, la silice mésoporeuse peut agir comme support potentiel pour ce type de catalyseurs hétérogènes. La silice mésoporeuse possède les propriétés physiques et chimiques adaptées tel que la surface spécifique élevés, le volume de pore grand, la taille des pores accordable et ajustable, et la facilité de fonctionnalisation de la surface. Par conséquent, l'objectif de cette thèse est d'explorer un procédé de synthèse facile pour préparer 'un catalyseur d'acide de Lewis hétérogène efficace en utilisant la silice mésoporeuse ordonnée fonctionnalisé par des métaux peu couteux. Pour cela, les silices mésoporeuses du type MCM-41, et SBA-15 ont été choisis comme supports de catalyseur. Par la suite, Fe- MCM-41 et Fe-SBA-15 ont été correctement synthétisé en utilisant un procédé polyvalent. Le traitement de l'ammoniac au cours de la synthèse a été trouvé être un moyen efficace d'augmenter la teneur en fer tout en préservant la dispersion convenable des cations métalliques. Les paramètres physicochimiques de la silice mésoporeuse finale contenant du fer ont été obtenus par l'analyse d'adsorption-désorption d'azote à la base température, et l'environnement de la coordination des éléments en fer a été validé par la spectroscopie de UV-Vis réflectance diffusée et la spectroscopie photoélectronique à rayons X. L'acidité de surface a été sondé à l'aide des indicateurs de Hammett. Pour distinguer en outre les sites acides de Lewis sur la surface, l'adsorption de pyridine suivie par FTIR a été mise en oeuvre. Ces catalyseurs préparés ont été criblés dans la réaction d'aldolisation de Mukaiyama, qui est une réaction modèle catalysée par l'acide de Lewis. L'activité catalytique acide de Lewis des matériaux était peaufinées et les produits aldol ont été obtenus avec un bon rendement et la sélectivité. De plus, les catalyseurs hétérogènes sont très stables et peuvent être réutilisés au moins neuf fois en conservant l'activité catalytique.
Download or read book Synthesis of Functionalised Mesoporous Silica for Capture and Transformation of Carbon Dioxide written by Maria Zakharova and published by . This book was released on 2017 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nowadays over 80% of the chemical industry is based on heterogeneous catalytic processes supplying us with energy, aliments, medicines, crop protection, and new commodities. Even though catalysis remains a strategic field of chemistry, the level of understanding of heterogeneous catalysis is still quite limited, especially when compared to that of homogeneous catalysis. In the present work, we try to expand the knowledge of heterogeneous catalytic systems based on functionalized hybrid mesoporous silica and probe them in different green chemistry processes, especially in relation to the capture and transformation of CO2. For CO2 capture, the well-known concept of frustrated Lewis pairs is translated on the surface of mesoporous silica, resulting in the synthesis of stable heterogenized Lewis acid-base pairs. Firstly, the synthesis of Al-, Ti-, Zr-SBA-15 mesoporous silica carrying very strong Lewis acidic character through the reaction of surface silanol groups with homogeneous metallic complexes is presented. The ability of these materials to catalyse the direct amidation of electron-poor and bulky amines supports the presence of highly active Lewis acidic metallic centers and their water-tolerance. Furthermore, the development of solid supported frustrated Lewis pairs (sFLPs) using Al-, Ti-, Zr-SBA-15 mesoporous silica is discussed. A series of conventional Lewis bases, such as diethylenetriamine, diphenylphosphine derivatives, triethylamine, and tetramethylpiperidine are grafted or impregnated on the surface of Ti-, Al-, Zr-SBA-15 to generate air-stable solid-supported Lewis acid-base pairs. The preservation of both Lewis acidic and basic properties after the solid Lewis acid-base pairs are formed is examined. Study of their interactions with CO2 is performed using solid state NMR spectroscopy and CO2 adsorption experiments, which provides a new insight in their applicability as solid CO2 adsorbents. A correlation between the solid supported Lewis acid-base pair strength and the affinity to CO2 is proposed based on the calculation of isosteric heat of adsorption. For CO2 transformation, the study of confinement effect in silica nanopores and its application in catalytic cycloaddition of carbon dioxide to epoxides is presented. The synthesis of hybrid mesoporous adsorbents of CO2 on the base of MCM-41 and SBA-15 silica is performed and the criteria for an efficient catalytic system are defined and optimised, providing a novel and very efficient heterogeneous catalyst, capable of performing the transformation of carbon dioxide at room temperature under an atmospheric pressure without any chemical pre-activation of starting materials.
Download or read book Micro Mesoporous Metallosilicates written by Peng Wu and published by John Wiley & Sons. This book was released on 2024-05-28 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro-Mesoporous Metallosilicates Up-to-date and in-depth text bridging the technology gap between fundamental research and industry-scale applications of porous materials for catalysis Micro-Mesoporous Metallosilicates: Synthesis, Characterization, and Catalytic Applications comprehensively introduces the chemistry and catalytic technologies of metallosilicates, an important family of microporous crystalline zeolite and heteroatom-containing mesoporous materials, with a primary focus on design synthesis, characterization, theoretical studies, and catalytic applications of titanosilicates, tin-silicates, germanosilicates and Ti-mesosilica, and more. The text covers recent advances in the synthesis of titanosilicates, including hydrothermal synthesis, dry-gel conversion, fluoride-assisted synthesis, and post-synthesis methods, along with the synthesis of metallosilicates with two-dimensional lamellar structures and their structural modifications as well as applications in selective oxidation reactions. The text also discusses synthesis of germanosilicates with specially designed organic structure-directing agents, synthesis and catalytic applications of heteroatom-containing mesoporous silica, and dendritic mesoporous silica nanoparticles with unique wrinkled center-radial structures. Overall, every important porous metallosilicate and its synthesis, characterization, pore engineering, catalytic application, and industrial technique and process are covered. Specific sample topics discussed in Micro-Mesoporous Metallosilicates include: Chemical post-modifications of titanosilicates, in terms of the effects on transfer, adsorption/desorption, and surface reactions X-Ray based techniques, ultraviolet-visible-near infrared spectroscopy, Raman spectroscopy, and solid-state NMR spectroscopy Theoretical calculation as an effective tool and supplement to understand the catalytic active center, structural character, and Brønsted/Lewis acidity Titanosilicates in the liquid-phase epoxidation reaction of propylene and propylene chloride to corresponding epoxides Effects of particle sizes, oxidation state, and location sites of Au nanoparticles, and epoxidation performance of Ti-containing materials Delivering cutting-edge research and bridging the technology gap between fundamental research and industrial applications, Micro-Mesoporous Metallosilicates is a valuable resource for chemists, materials scientists, chemical engineers, and experienced researchers in related fields.
Download or read book Microporous and Mesoporous Solid Catalysts written by Eric G. Derouane and published by John Wiley & Sons. This book was released on 2006-08-14 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series offers practical help for advanced undergraduate, graduate and postgraduate students, as well as experienced chemists in industry and academia working with catalysts in organic and organometallic synthesis. It features tested and validated procedures, authoritative reviews on classes of catalysts, and assessments of all types of catalysts. Micro- and Mesoporous Solid Catalysts describes the use of zeolites and mesoporous solids as catalysts for the production of fine and specialty chemicals. Specific tips and hints are provided and some typical procedures are described in detail In addition to discussing the pros and cons, several major organic transformations are examined including aromatic substitutions, heterocyclic ring formation, amines synthesis, oligomerisation, oxidation and hydroxylation, and other regioselective and stereoselective reactions Features tutorial introductory chapters, including tips and hints for achieving successful organic transformations Important reactions are featured together with recommendations to resolve potential problems.
Download or read book Mesoporous Zeolites written by Javier García-Martínez and published by John Wiley & Sons. This book was released on 2015-05-26 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by a top-level team of both academic and industrial researchers in the field, this is an up-to-date review of mesoporous zeolites. The leading experts cover novel preparation methods that allow for a purpose-oriented fine-tuning of zeolite properties, as well as the related materials, discussing the specific characterization methods and the applications in close relation to each individual preparation approach. The result is a self-contained treatment of the different classes of mesoporous zeolites. With its academic insights and practical relevance this is a comprehensive handbook for researchers in the field and related areas, as well as for developers from the chemical industry.
Download or read book Characterization of a Silica supported Iron Lewis Acid Catalyst written by Daniel J. Casper and published by . This book was released on 2002 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modern Organic Synthesis written by George S. Zweifel and published by John Wiley & Sons. This book was released on 2017-03-13 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges the gap between sophomore and advanced / graduate level organic chemistry courses, providing students with a necessary background to begin research in either an industry or academic environment. • Covers key concepts that include retrosynthesis, conformational analysis, and functional group transformations as well as presents the latest developments in organometallic chemistry and C–C bond formation • Uses a concise and easy-to-read style, with many illustrated examples • Updates material, examples, and references from the first edition • Adds coverage of organocatalysts and organometallic reagents
Download or read book Green Chemistry and Catalysis written by R. A. Sheldon and published by John Wiley & Sons. This book was released on 2007-06-27 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first book to focus on catalytic processes from the viewpoint of green chemistry presents every important aspect: · Numerous catalytic reductions and oxidations methods · Solid-acid and solid-base catalysis · C-C bond formation reactions · Biocatalysis · Asymmetric catalysis · Novel reaction media like e.g. ionic liquids, supercritical CO2 · Renewable raw materials Written by Roger A. Sheldon -- without doubt one of the leaders in the field with much experience in academia and industry -- and his co-workers, the result is a unified whole, an indispensable source for every scientist looking to improve catalytic reactions, whether in the college or company lab.
Download or read book Highly Efficient and Shape Selective Solid Acid Catalysts Based on Mesoporous Silica written by Yong Wang and published by . This book was released on 1998 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Green Sustainable Process for Chemical and Environmental Engineering and Science written by Rajender Boddula and published by Elsevier. This book was released on 2020-06-19 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Green Sustainable Process for Chemical and Environmental Engineering and Science: Sonochemical Organic Synthesis focuses on purification and extraction of organic, biological, and medicinal compounds using sonochemistry. It provides readers with an understanding of green ultrasound-assisted chemical synthesis for industrial applications. This book systematically explores the application of ultrasound in organic synthesis of all types and includes stereoselectivity, regioselectivity, oxidations, reductions, protection, deprotection, additions, condensation, coupling, C-X bond formation, named reactions, heterocyclics, biological drugs, and fluoroorganics over conventional techniques. A brief introduction to the parameters which influence the process, solvent-effects, supported reagents and catalysis and the pros and cons to the practical use of sonochemical protocols in organic synthesis are also discussed. This book provides overview on the applications of sonochemical technology for the sustainable and environmentally friendly development of synthetic methodologies for organic and pharmaceutical chemistry. Sonochemical Organic Synthesis is an essential resource on green chemistry technologies for academic researchers, R&D professionals, and students working in modern organic chemistry and medicinal chemistry. - Offers a broad overview of ultrasonics-assisted green organic synthesis - Discusses sonochemical technology for green organic synthesis and biological medicinal importance - Gives detailed accounts of numerous industrial applications, including polymers, pharmaceutical, fluoroorganics, biofuel, carbon, and more - Includes a description of significant factors and challenges in ultrasonics-assisted green organic synthesis - Lists recent developments in the use of sonochemical technology in organic chemist
Download or read book Design of Catalytic Domains Within Organosulfonic Acid functionalized Mesoporous Silica written by Isa Kipkoech Mbaraka and published by . This book was released on 2005 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic-inorganic hybrid mesoporous silicas were synthesized via nonionic supramolecular assembly using the co-condensation synthesis technique with the intention of understanding the catalytic domain as well as developing strategies to control the catalytic functionalities at the molecular level. Esterification of free fatty acids in natural oils and fats was used to probe the catalytic activity of the synthesized acid-modified mesoporous catalysts. Application of solid acid catalysts in such reaction systems can possibly simplify the manufacturing process, reducing production costs, as well as eliminate environmental hazards posed by toxic wastes generated in homogeneous catalyzed reactions. The catalytic performance of the functionalized mesoporous silicas was significantly influenced by the median pore diameter of the catalyst, which was tuned using different surfactants. Incorporation of hydrophobic groups into the organic-inorganic acid catalyst enhanced the catalytic conversion of the fatty acids, although the catalytic performance of the resulting catalyst strongly depended on the incorporation technique as well as the size of the hydrophobic organic groups. Decreasing the spatial positioning of the sulfonic acid groups on the pore surface of mesostructured material increased the acid strength of the resulting acid catalyst. This study demonstrated that the catalytic properties of the functionalized mesoporous catalyst were complex and reaction kinetics studies alone could overlook other important factors, such as solution effects, site collaboration, and hydrophobicity of the catalytic domain, that could affect the ultimate performance of the acid solid catalyst. The work demonstrates the potential of intentionally designing the catalytic environment of the organic-inorganic hybrid mesoporous materials at the molecular level.
Download or read book Advanced Functional Solid Catalysts for Biomass Valorization written by Chaudhery Mustansar Hussain and published by Elsevier. This book was released on 2020-06-14 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Functional Solid Catalysts for Biomass Valorization presents the basic concepts in catalysis (homogeneous, heterogeneous, and enzymatic) and the properties of various kinds of heterogeneous solid catalysts, including their structure, porosity, particle size, BET surface area, acid-base, and redox properties. Useful information about biorefineries, types of biomass feedstocks, their structures and properties as well as about several potential catalytic routes for biomass upgrading to useful fuels and chemicals is provided in this book. Importantly, this book covers the most recent developments toward functionalization of various solid catalysts, optimization of catalysts' properties, developing cascade catalytic strategies, exploring reaction kinetics/mechanisms, and evaluating catalysts' stability/reusability during biomass upgrading. Current challenges and opportunities for the future biorefineries as well as for the design of advanced functional solid catalysts are critically discussed. Describes catalysis as a promising technology for the development of eco-friendly and economically viable strategies for several important energy and environmental applications. Covers heterogeneous solid catalysts because of their versatile benefits in terms of catalysts' synthesis, production cost, stability, and reusability as compared to homogeneous liquid catalysts. Provides promising strategies for the design of new catalytic materials, such as carbon materials, metal-organic frameworks, zeolites, and mesoporous silicas. Describes functional solid catalysts for developing one-pot cascade processes for efficient biomass valorization and other vital chemical transformations.
Download or read book Metal Oxides in Heterogeneous Catalysis written by Jacques C. Vedrine and published by Elsevier. This book was released on 2018-01-11 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxides in Heterogeneous Catalysis is an overview of the past, present and future of heterogeneous catalysis using metal oxides catalysts. The book presents the historical, theoretical, and practical aspects of metal oxide-based heterogeneous catalysis. Metal Oxides in Heterogeneous Catalysis deals with fundamental information on heterogeneous catalysis, including reaction mechanisms and kinetics approaches.There is also a focus on the classification of metal oxides used as catalysts, preparation methods and touches on zeolites, mesoporous materials and Metal-organic frameworks (MOFs) in catalysis. It will touch on acid or base-type reactions, selective (partial) and total oxidation reactions, and enzymatic type reactions The book also touches heavily on the biomass applications of metal oxide catalysts and environmentally related/depollution reactions such as COVs elimination, DeNOx, and DeSOx. Finally, the book also deals with future trends and prospects in metal oxide-based heterogeneous catalysis. - Presents case studies in each chapter that provide a focus on the industrial applications - Includes fundamentals, key theories and practical applications of metal oxide-based heterogeneous catalysis in one comprehensive resource - Edited, and contributed, by leading experts who provide perspectives on synthesis, characterization and applications
Download or read book Organically Modified Mesoporous Silica as a Support for Synthesis and Catalysis written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoporous silicates are excellent materials for supported catalysis due to their ease of functionalization, tunable pore size and high surface areas. Mesoporous silicates have been utilized in a variety of applications such as drug delivery scaffolds and catalyst supports. Functionalization of the surface can be achieved by either grafting of alkoxy silanes or co-condensation of the organosilane with the inorganic silica source. My research in this area can be divided into two components. In the first, we address the significant issue of metal contamination after reactions that are catalyzed by transition metals. In the second, we examine the design of new catalysts based on organic/inorganic composites. Ruthenium catalyzed processes such as olefin metathesis or asymmetric hydrogenation, are often underutilized due to the difficulty of removing the ruthenium by-products. Attempts to remove ruthenium involve treating the solution with a scavenging reagent followed by silica chromatography. Often these scavenging agents are expensive phosphines or toxic agents like lead tetra-acetate. SBA-15 functionalized with aminopropyl triethoxysilane displays a high affinity for ruthenium. Furthermore, it can be utilized to remove ruthenium by-products from olefin metathesis or hydrogenation reactions without the need for silica chromatography. We have also prepared sulfur-functionalized mesoporous silicates that have a high affinity for palladium. The materials after loading prove to be active catalysts for a variety of palladium catalyzed processes such as Suzuki-Miyaura and Sonogashira couplings. The catalysts are recyclable with moderate loss of activity and structure, depending on the method of incorporation of the thiol. We have characterized the as-synthesized and used catalysts by nitrogen sorption, TEM, X-ray photoelectron spectroscopy (XPS) and a variety of homogeneity tests were performed on the catalysts. Periodic mesoporous organosilicates (PMOs) are a well known cl.
Download or read book Surface Organometallic Chemistry Molecular Approaches to Surface Catalysis written by Jean-Marie Basset and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface organometallic chemistry is a new field bringing together researchers from organometallic, inorganic, and surface chemistry and catalysis. Topics ranging from reaction mechanisms to catalyst preparation are considered from a molecular basis, according to which the "active site" on a catalyst surface has a supra-molecular character. This. the first book on the subject, is the outcome of a NATO Workshop held in Le Rouret. France, in May. 1986. It is our hope that the following chapters and the concluding summary of recommendations for research may help to provide a definition of surface organometallic chemistry. Besides catalysis. the central theme of the Workshop, four main topics are considered: 1) Reactions of organometallics with surfaces of metal oxides, metals. and zeolites; 2) Molecular models of surfaces, metal oxides, and metals; 3) Molecular approaches to the mechanisms of surface reactions; 4) Synthesis and modification of zeolites and related microporous solids. Most surface organometallic chemistry has been carried out on amorphous high-surf ace-area metal oxides such as silica. alumina. magnesia, and titania. The first chapter. contributed by KNOZINGER. gives a short summary of the structure and reactivity of metal oxide surfaces. Most of our understanding of these surfaces is based on acid base and redox chemistry; this chemistry has developed from X-ray and spectroscopic data, and much has been inferred from the structures and reactivities of adsorbed organic probe molecules. There are major opportunities for extending this understanding by use of well-defined (single crystal) oxide surfaces and organometallic probe molecules.
Download or read book Advances in Organic Synthesis written by Atta-ur-Rahman and published by Bentham Science Publishers. This book was released on 2018-08-01 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Organic Synthesis is a book series devoted to the latest advances in synthetic approaches towards challenging structures. The series presents comprehensive reviews written by eminent authorities on different synthetic approaches to selected target molecules and new methods developed to achieve specific synthetic transformations or optimal product yields. Advances in Organic Synthesis is essential for all organic chemists in academia and the industry who wish to keep abreast of rapid and important developments in the field. This volume presents the following reviews: • Asymmetric hydrogenation of tetrasubstituted olefins • Recent advances in catalytic organic synthesis applications of covalently supported ionic liquids • Recent developments in intramolecular cyclization reactions via carbon-heteroatom (c-x) bond formation • Efficient synthetic protocol and mechanistic study of quinazoline analogues and their biological importance • Synthesis of N,O,S-heterocycles by one-pot reactions of epoxides, aziridines and oxaziridines
