Synthesis and characterization of modified silica-zirconia mixed oxide catalysts PDF Download
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Author: Daniel J. Rosenberg
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages :
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Author: Daniel J. Rosenberg
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages :
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Author: Andrew Justin Binder
Publisher:
ISBN:
Category : Carbon monoxide
Languages : en
Pages : 156
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Heterogeneous catalysts are responsible for billions of dollars of industrial output and have a profound, if often understated, effect on our everyday lives. New catalyst technologies and methods to enhance existing catalysts are essential to meeting consumer demands and overcoming environmental concerns. This dissertation focuses on the development of catalysts for low temperature carbon monoxide oxidation. CO [carbon monoxide] oxidation is often used as a probe reaction to test overall oxidation activity of a given catalyst and is an important reaction in the elimination of toxic pollutants from automotive exhaust streams. The work included here presents three new heterogeneous catalysts developed over the last 4 years in our group. The first type Au/SiO2 [gold/silica] catalyst synthesized using a new method for the deposition of Au nanoparticles onto SiO2 via a nitrogen-containing polymer, C3N4 [carbon nitride]. C3N4-modification of SiO2 allows us to ignore unfavorable electrostatic effects that hinder standard Au deposition onto this support. While removal of the C3N4 is necessary for good CO oxidation, this new method is an improvement over the standard deposition-precipitation procedure for supports with low isoelectric point that enables the successful deposition of Au nanoparticles onto SiO2. The second type includes precious metal catalysts deposited on an “inert” silica support but promoted by the addition of an “active” metal oxide. Here we present a Au/FeOx̳/SiO2 [gold/iron oxide/silica] and a Pd/ZrO2/SiO2 [palladium/zirconia/silica] catalyst which show increased activity and stability effects due to the presence of the metal oxide promoter. They are synthesized by a C3N4-deposition and sol-gel methods, respectively. These catalysts were also tested in simulated automotive exhaust streams. The results show that inhibition effects play a major role in the activity of these catalysts. The third type of catalyst is a mixed oxide catalyst, CuO-Co3O4-CeO2 [copper oxide-cobalt oxide-cerium oxide], developed with the goal of overcoming the inhibition effects seen in the previous precious metal catalysts. The catalyst was synthesized by co-precipitation method and shows exceptional activity for CO oxidation under simulated exhaust conditions. Also noteworthy is the observation that this catalyst also shows a lack of inhibition by a common exhaust component, propene.
Author: Carla Eponina Hori
Publisher:
ISBN:
Category :
Languages : en
Pages : 312
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Author:
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ISBN:
Category :
Languages : en
Pages :
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Silica nanoparticles and zirconia coated silica nanoparticles were prepared by Stober method.and various subsequent methods. The nanoparticles obtained were characterized by XRD, SEM, EDAX and IR analytical techniques. The XRD study of pure ZrO2 shows well crystalline characteristics with the presence of 100% monoclinic phase. The coated nanoparticles are found to be amorphous in nature. SEM study indicate the particles to possess disorder morphology with the particle are attached to each other through grain boundary to form agglomerated structure. The zirconia coated silica nanoparticles were used as a efficient catalyst for the synthesis of Bis(indolyl) methane under solvent free condition. The Bis(indolyl) methane were obtained with high yield and purity.
Author: Yue Zhang
Publisher:
ISBN: 9781361310243
Category :
Languages : en
Pages :
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This dissertation, "Synthesis and Characterization of Zirconia Based Solid Acid Catalysts for Biodiesel Production" by Yue, Zhang, 张悦, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Biodiesel is a promising renewable alternative fuel to fossil energy. For the biodiesel production from low-cost feedstock, a pretreatment step is essential, which is the esterification of free fatty acids (e.g. oleic acid) in the feedstock in order to avoid soap formation and minimize catalyst deactivation. Sulfuric acid modified zirconia (H2SO4-ZrO2) is known as an effective heterogeneous catalyst for esterification. However, due to rapid 〖SO〗_4 DEGREES(2-) leaching, its reusability is low and its practical use is thus largely hindered. Zirconia supported on silica (ZrO2-SiO2) serves as a kind of non-sulfated zirconia catalyst against the leaching of the active species. Moreover, the silica support offers a large surface area and excellent thermal stability, which can accommodate a number of active zirconia species. Furthermore, there are Zr-O-Si bondings at the contact area between ZrO2 and SiO2, which might result in the formation of a new strong acid species and induce an increase of the zirconia acidity accordingly. Herein, two types of ZrO2-SiO2 catalysts were prepared, by using the reverse microemulsion method and sol-gel-hydrothermal method, denoted as ZrO2-SiO2-ME and ZrO2-SiO2-SG, respectively. The as synthesized ZrO2-SiO2 were characterized by TEM, SEM, EDX, XRD, BET and IR. ZrO2-SiO2-ME demonstrated a good dispersion of ZrO2 nanoparticles, encapsulating in the monodispersed SiO2 host matrix, while ZrO2-SiO2-SG possessed the SiO2 support with a mesoporous structure, with an average pore size of 7 nm and a surface area of 418 m2/g. The catalysts both exhibited excellent catalytic activity and stable performance in the esterification of oleic acid. Besides non-sulfated zirconia, sulfated zirconia catalysts other than traditional H2SO4-ZrO2 were also developed as solid acid catalysts for biodiesel production. Two sulfur-containing strong acids, chlorosulfonic acid (HClSO3) and (NH4)2SO4, were employed to acidify ZrO2, and two sulfated zirconia catalysts were prepared accordingly, namely HClSO3-ZrO2 and S-ZrO2. They were characterized by SEM, EDX, XRD, BET, IR, TGA and NH3-TPD. Comparing with H2SO4-ZrO2, HClSO3-ZrO2 and S-ZrO2 contained higher sulfur content and more acid sites. More importantly, both HClSO3-ZrO2 and S-ZrO2 demonstrated high catalytic activity and excellent durability in the esterification of oleic acid. It is known that consecutive esterification and transesterification reactions are suitable for direct biodiesel production and acetylation of glycerol enables the conversion of this biodiesel byproduct to a biofuel additive. Therefore, all the above mentioned catalysts were examined to compare their catalytic abilities in these reactions. Among the four catalysts, HClSO3-ZrO2 exhibited the highest catalytic activity in both reactions under optimal conditions. The thesis work here described the preparation and characterization of four types of ZrO2-based solid acid catalysts. Their catalytic activities were thoroughly investigated upon the several essential steps in biodiesel production. In addition, the synthesis condition-activity relation was studied and the synthesis and reaction conditions were delicately tuned. DOI: 10.5353/th_b4985882 Subjects: Catalysts - Synthesis Zirconium oxide Biodiesel fuels
Author: R. Maggi
Publisher: Elsevier
ISBN: 0080539459
Category : Technology & Engineering
Languages : en
Pages : 1007
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The proceedings of the VIIth International Symposium on the Scientific Bases for the Preparation of Heterogeneous Catalysts, are in line with the general scope of this series of events. Emphasis in all Symposia has been on the scientific aspects of the preparation of new and industrial catalysts, or on new methods of preparation, rather than on the catalytic reactions in which such solids are ultimately used. In the present context, the catalytic event itself has only been considered as another, though often decisive, method of catalyst characterization.
Author: Peng Wu
Publisher: John Wiley & Sons
ISBN: 3527350942
Category : Technology & Engineering
Languages : en
Pages : 501
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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.
Author: Craig Fergusson
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages :
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Author: Dr T. E Mohan Kumar
Publisher: Krishna Publication House
ISBN: 9390627389
Category : Antiques & Collectibles
Languages : en
Pages :
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Author: Serena Esposito
Publisher: Springer Nature
ISBN: 3031207238
Category : Technology & Engineering
Languages : en
Pages : 78
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This book discusses the synthesis of catalytic materials with improved and tailored functionalities via the sol-gel method. Beginning with a general outline of traditional sol-gel chemistry, the book gradually explores surrounding topics, such as the formation of porous structures, while guiding the overall discussion toward the synthesis of heterogeneous catalysts and focusing throughout on the structure-activity relationship in catalytic materials. Featuring several case studies covering major current industrial applications, the book is an ideal guide for researchers looking to tailor catalytic materials for a specific catalytic process and thus exploiting the versatility of the “traditional” sol-gel method.
