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Author: Sayantani Das Publisher: ISBN: Category : Mesoporous materials Languages : en Pages : 183
Book Description
Novel multifunctional mesoporous and nanostructured catalysts containing two or more different types of judiciously chosen functional / catalytic groups were developed and their unique and cooperative catalytic activities in various useful organic reactions were explored. First, mesoporous silica material containing tertiary amine/silanol groups was synthesized by simple postgrafting synthetic method. The material was found to exhibit efficient cooperative acid/base bifunctional catalytic activity towards Michael addition reactions between trans-¿ø-nitrostyrene and various active methylene compounds such as malononitrile, acetylacetone and dimethylmalonate. Besides serving as a solid base catalyst, such organoamine-functionalized mesoporous silica materials can be utilized as effective support materials for catalytically active organometallic complexes. This was demonstrated by immobilizing ethylenediamine onto mesoporous silica via postgrafting synthetic method and then complexing Fe(III) onto the supported ethylenediamine groups. This yielded a bifunctional Fe(III)/silanol-based heterogeneous catalyst that showed efficient catalytic activity towards epoxide ring opening reactions. Next, the potential of these types of organic-functionalized mesoporous silicas for immobilization of metallic nanoparticle catalysts was investigated. Specifically, mercaptopropyl-functionalized mesoporous silica was synthesized and the material was then supported with ultrasmall Aun nanoclusters. The catalytic properties of the resulting materials in styrene oxidation were studied. Furthermore, the effect of the removal of the thiol groups from around the surfaces of the gold nanoclusters on catalytic activities of the mesoporous silica-supported nanoparticles was investigated. As mesoporous silica have some limitations of crowding in their pores and poor mass transport for reactants when they are functionalized with larger groups such as nanoparticles, a new strategy was developed, where such catalytic groups were immobilized on the outer surface of silica microspheres. These supported nanoparticle catalytic groups on the silica nanospheres were further coated with a porous silica shell in order to overcome their possible aggregation, sintering and loss of catalytic activities. The resulting nanomaterials, dubbed produced SiO2-Au-pSiO2 core-shell-shell microspheres, were then used as efficient and recyclable nanocatalysts for styrene epoxidation. This strategy was further extended to core-shell-shell microspheres containing the metal (e.g., Pd) nanoparticles within G4 PAMAM dendrimers that are supported on silica nanosphere cores and coated by nanoporous silica shells. These nanomaterials, denoted as SiO2-Pd/PAMAM-pSiO2 core-shell-shell microspheres, were shown to serve not only as efficient and recyclable catalysts but also as selective catalysts for specific functional groups in hydrogenation reaction of various substrates.
Author: Sayantani Das Publisher: ISBN: Category : Mesoporous materials Languages : en Pages : 183
Book Description
Novel multifunctional mesoporous and nanostructured catalysts containing two or more different types of judiciously chosen functional / catalytic groups were developed and their unique and cooperative catalytic activities in various useful organic reactions were explored. First, mesoporous silica material containing tertiary amine/silanol groups was synthesized by simple postgrafting synthetic method. The material was found to exhibit efficient cooperative acid/base bifunctional catalytic activity towards Michael addition reactions between trans-¿ø-nitrostyrene and various active methylene compounds such as malononitrile, acetylacetone and dimethylmalonate. Besides serving as a solid base catalyst, such organoamine-functionalized mesoporous silica materials can be utilized as effective support materials for catalytically active organometallic complexes. This was demonstrated by immobilizing ethylenediamine onto mesoporous silica via postgrafting synthetic method and then complexing Fe(III) onto the supported ethylenediamine groups. This yielded a bifunctional Fe(III)/silanol-based heterogeneous catalyst that showed efficient catalytic activity towards epoxide ring opening reactions. Next, the potential of these types of organic-functionalized mesoporous silicas for immobilization of metallic nanoparticle catalysts was investigated. Specifically, mercaptopropyl-functionalized mesoporous silica was synthesized and the material was then supported with ultrasmall Aun nanoclusters. The catalytic properties of the resulting materials in styrene oxidation were studied. Furthermore, the effect of the removal of the thiol groups from around the surfaces of the gold nanoclusters on catalytic activities of the mesoporous silica-supported nanoparticles was investigated. As mesoporous silica have some limitations of crowding in their pores and poor mass transport for reactants when they are functionalized with larger groups such as nanoparticles, a new strategy was developed, where such catalytic groups were immobilized on the outer surface of silica microspheres. These supported nanoparticle catalytic groups on the silica nanospheres were further coated with a porous silica shell in order to overcome their possible aggregation, sintering and loss of catalytic activities. The resulting nanomaterials, dubbed produced SiO2-Au-pSiO2 core-shell-shell microspheres, were then used as efficient and recyclable nanocatalysts for styrene epoxidation. This strategy was further extended to core-shell-shell microspheres containing the metal (e.g., Pd) nanoparticles within G4 PAMAM dendrimers that are supported on silica nanosphere cores and coated by nanoporous silica shells. These nanomaterials, denoted as SiO2-Pd/PAMAM-pSiO2 core-shell-shell microspheres, were shown to serve not only as efficient and recyclable catalysts but also as selective catalysts for specific functional groups in hydrogenation reaction of various substrates.
Author: Esteban A. Franceschini Publisher: CRC Press ISBN: 1000378926 Category : Science Languages : en Pages : 323
Book Description
The development of nanomaterials plays a fundamental role in current and future technology applications, particularly nanomaterials that have multiple functionalities. This book provides a broad overview of the effect of nanostructuring in the multifunctionality of different widely studied nanomaterials. This book is divided into four sections constituting a road map that groups materials sharing certain types of nanostructuring, including nanoporous, nanoparticled, 2D laminar nanomaterials, and computational methods for characterizations of nanostructures. This structured approach in nanomaterials research will serve as a valuable reference material for chemists, (bio)engineers, physicists, nanotechnologists, undergraduates, and professors.
Author: Susannah L. Scott Publisher: Springer Science & Business Media ISBN: 0387306412 Category : Science Languages : en Pages : 341
Book Description
With the recent advent of nanotechnology, research and development in the area of nanostructured materials has gained unprecedented prominence. Novel materials with potentially exciting new applications are being discovered at a much higher rate than ever before. Innovative tools to fabricate, manipulate, characterize and evaluate such materials are being developed and expanded. To keep pace with this extremely rapid growth, it is necessary to take a breath from time to time, to critically assess the current knowledge and provide thoughts for future developments. This book represents one of these moments, as a number of prominent scientists in nanostructured materials join forces to provide insightful reviews of their areas of expertise, thus offering an overall picture of the state-- the art of the field. Nanostructured materials designate an increasing number of materials with designed shapes, surfaces, structures, pore systems, etc. Nanostructured materials with modified surfaces include those whose surfaces have been altered via such techniques as grafting and tethering of organic or organometallic species, or through various deposition procedures including electro, electroless and vapor deposition, or simple adsorption. These materials find important applications in catalysis, separation and environmental remediation. Materials with patterned surfaces, which are essential for the optoelectronics industry, constitute another important class of surface-modified nanostructured materials. Other materials are considered nanostructured because of their composition and internal organization.
Author: Marco Piumetti Publisher: Springer Nature ISBN: 303058934X Category : Technology & Engineering Languages : en Pages : 435
Book Description
This book offers an overview of the recent studies and advances in environmental catalysis by nanomaterials, considering both the fundamental and the technological aspects. It offers contributions in different areas of environmental catalysis, including the catalytic and photocatalytic abatement of environmentally hazardous effluents from stationary or mobile sources, the valorization of waste and the production of sustainable energy. In other words, this monograph provides an overview of modern environmental and energy related applications with a particular emphasis to nano-sized catalytic materials. Recent concepts, experimental data and advanced theories are reported in this book to give evidence of the environmental and sustainable applications that can be found in the highly interdisciplinary field of catalysis.
Author: Publisher: ISBN: Category : Languages : en Pages : 43
Book Description
Selective catalysis is a field that has been under intense investigation for the last 100 years. The most widely used method involves catalysts with stereochemical selectivity. In this type of catalysis, the catalyst controls which reactants will be transformed into the desired product. The secret to employing this type of catalysis, though, is to design the proper catalyst, which can be difficult. One may spend as much time developing the catalyst as spent separating the various products achieved. Another method of selective catalysis is now being explored. The method involves utilizing a multifunctional mesoporous silica catalyst with a gate-keeping capability. Properly functionalized mesoporous materials with well-defined pore morphology and surface properties can provide an ideal three-dimensional environment for anchoring various homogeneous catalysts. These materials can circumvent the multi-sited two-dimensional nature most heterogeneous systems have without adversely impacting the reactant diffusivity. These single-site nanostructured catalysts with ordered geometrical structure are advantageous in achieving high selectivity and reactivity. Mesoporous materials can be prepared to include pores lined homogeneously with tethered catalysts via co-condensation. Additionally, these materials can be reacted with another (RO)3SiZ̃ group by using the traditional grafting method; this group is anchored predominantly at the entrances to the pores rather than inside the pores. Thus, if these Z̃ groups are chosen properly, they can select certain molecules to enter the pores and be converted to products (Scheme 1). In such multifunctional catalysts, the selectivity depends on the discrimination of the gatekeeper. Gate-keeping MCM-41 materials are at the forefront of catalytic substances.
Author: Kasey Jean Strosahl Publisher: ISBN: Category : Languages : en Pages : 78
Book Description
The unique properties of bifunctionalized MCM-41 prove it to be a valuable tool in the catalytic field. The primary functional group (i.e. acid/base, metal center) enables the reaction to proceed as the typical homogeneous reaction would; however, the secondary group places restrictions upon the catalytic reaction. The secondary group acts as a gatekeeper, only allowing the appropriate reactants to diffuse into the material's mesopores. In this work, hydrophobic pentafluorophenyl groups are co-condensed as secondary groups onto the inner surface of the pores. These secondary groups increase the hydrophobicity of the mesopores. By utilizing an aqueous solvent, then, one can control which reactants diffuse into the pores to interact with the catalyst. Herein, a Sharpless-type reaction between an organic azide and a terminal acetylene is effectively catalyzed using a copper/pentafluorophenyl MCM-41 material. The reaction's success depends upon the solvent employed-water versus benzene; therefore, the reaction is an example of how one can manipulate a catalytic reaction's yield by varying the reactant/solvent properties. Another reaction scheme is described where a molecule containing both hydrophobic and hydrophilic tails can be forced into a certain conformation by the hydrophobic MCM -41 in an aqueous solution to produce a syn elimination to a cis olefin. This method allows one to control the regiochemistry of the catalytic reaction. Numerous other types of reactions, including stereospecific reactions, could also be catalyzed using this same idea if modified to correspond with the appropriate characteristics.
Author: An-Hui Lu Publisher: Royal Society of Chemistry ISBN: 0854041885 Category : Science Languages : en Pages : 279
Book Description
Nanostructured materials with tailored properties are regarded as a fundamental element in the development of future science and technology. Research is still ongoing into the nanosized construction elements required to create functional solids. The recently developed technique, nanocasting, has great advantage over others in terms of the synthesis of special nanostructured materials by the careful choice of suitable elements and nanoengineering steps. This new book summarizes the recent developments in nanocasting, including the principles of nanocasting, syntheses of novel nanostructured materials, characterization methods, detailed synthetic recipes and further possible development in this area. The book focuses on the synthesis of porous solids from the viewpoint of methodology and introduces the science of nanocasting from fundamental principles to their use in synthesis of various materials. It starts by outlining the principles of nanocasting, requirements to the templates and precursors and the tools needed to probe matter at the nanoscale level. It describes how to synthesize nano structured porous solids with defined characteristics and finally discusses the functionalization and application of porous solids. Special attention is given to new developments in this field and future perspectives. A useful appendix covering the detailed synthetic recipes of various templates including porous silica, porous carbon and colloidal spheres is included which will be invaluable to researchers wanting to follow and reproduce nanocast materials. Topics covered in the book include: * inorganic chemistry * organic chemistry * solution chemistry * sol-gel and interface science * acid-base equilibria * electrochemistry * biochemistry * confined synthesis The book gives readers not only an overview of nanocasting technology, but also sufficient information and knowledge for those wanting to prepare various nanostructured materials without needing to search the available literature.
Author: Bing Zhou Publisher: Springer Science & Business Media ISBN: 9780306483233 Category : Science Languages : en Pages : 416
Book Description
This book is mainly based on the first and second symposia on Nanotechnology in Catalysis held in 2001 and 2002, but it also includes several contributions not presented in the symposia to round out the scope of the subject. The contents are the most up to date developments made by researchers all over the world in the catalysis field in this fascinating nanotechnology era. It reflects some of the frontier areas of nanoscience and nanotechnology in fabricating and characterizing catalysts and carrying out studies to prove their superior selectivity and activity. The field of application of nanotechnology for the development of catalysts for green chemistry is likely to grow rapidly during the next decade. This book hopes to contribute to the evolution of nanotechnology in that direction.
Author: Bert Sels Publisher: John Wiley & Sons ISBN: 352769983X Category : Technology & Engineering Languages : en Pages : 1500
Book Description
Reflecting the R&D efforts in the field that have resulted in a plethora of novel applications over the past decade, this handbook gives a comprehensive overview of the tangible benefits of nanotechnology in catalysis. By bridging fundamental research and industrial development, it provides a unique perspective on this scientifically and economically important field. While the first three parts are devoted to preparation and characterization of nanocatalysts, the final three provide in-depth insights into their applications in the fine chemicals industry, the energy industry, and for environmental protection, with expert authors reporting on real-life applications that are on the brink of commercialization. Timely reading for catalytic chemists, materials scientists, chemists in industry, and process engineers.
Author: Sayantani Das
Author: Sayantani Das
Author: Esteban A. Franceschini
Author: Susannah L. Scott
Author: Marco Piumetti
Author: 
Author: Kasey Jean Strosahl
Author: An-Hui Lu
Author: Bing Zhou
Author: Lorenz Bock
Author: Bert Sels