Characterization of Silica Supported Chromium Oxide Catalysts Used for the Oxidation of Chlorinated Hydrocarbons PDF Download
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Author: John F. Spero
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 364
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Author: John F. Spero
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 364
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Author: Wade H. Shafer
Publisher: Springer Science & Business Media
ISBN: 1461524539
Category : Science
Languages : en
Pages : 391
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Book Description
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the though that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemi nation. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 37 (thesis year 1992) a total of 12,549 thesis titles from 25 Canadian and 153 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 37 reports theses submitted in 1992, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
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: Nuwan Dileepa De Silva
Publisher:
ISBN:
Category :
Languages : en
Pages : 130
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The dissertation describes research work on development of bimetallic heterogeneous catalysts for oxidation of organic compounds. Binuclear metal complexes are an interesting class of compounds due to their catalytic activity. The approach involves anchoring a triketone ligand to Cab-O-Sil via a linker. Specifically, silica gel was allowed to react with p-chloromethylphenyltrimethoxysilane followed by coupling with deprotonated triketone compounds. The viability of this approach was verified by performing the benzylation reaction of triketones with benzyl halides under basic conditions. The benzylation of 2,4,6-heptanetrione and 1,5-diphenyl-1,3,5-pentanetrione is achieved with benzyl bromide using n-tetrabutylammonium fluoride as base. These benzylation reaction conditions were used to attach the triketones to the surface-attached linker. Once the ligand is attached to the silica gel, the catalyst is formed by coordinating two copper(II) ions from solution to the deprotonated triketone. The coordination of copper(II) ions to the triketone was monitored using UV-vis spectroscopy. The modified silica gel is characterized by diffuse reflectance infrared Fourier spectroscopy (DRIFTS), and thermal gravimetric analysis (TGA) at the different stages of catalyst formation. All techniques indicated significant attachment of linker and triketone to the support. The oxidation of 3,5-di-tert-butyl catechol (DTBC) and benzyl alcohol was carried out under aerobic conditions using these catalysts. The kinetics of the DTBC oxidation and benzyl alcohol oxidation was studied using bimetallic and monometallic catalytic systems. The copper complexes of the triketone ligands were also evaluated as catalysts for the oxidation of DTBC. New bimetallic metal complexes with triketone ligands having a benzyl group were synthesized and characterized by high resolution mass spectroscopy and IR spectroscopy. In addition to a detailed description of the synthesis and characterization of new triketone compounds, and the heterogeneous catalyst systems, a comparison of the kinetics of the oxidation of DTBC using these catalysts will be discussed.
Author: W. H. Shafer
Publisher: Springer Science & Business Media
ISBN: 9780306447112
Category : Education
Languages : en
Pages : 410
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Book Description
Volume 37 (thesis year 1992) reports a total of 12,549 thesis titles from 25 Canadian and 153 US universities (theses submitted in previous years but only now reported are indicated by the thesis year shown in parenthesis). The organization, like that of past years, consists of thesis titles arrange
Author: Sanmei Xu
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 118
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Author: Karl C. Stein
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 1200
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Author: Rebecca Anne Shiels
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages :
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Catalysis is an important field of study in chemical engineering and chemistry due to its application in a vast number of chemical transformations. Traditionally, catalysts have been developed as homogeneous molecular species or as heterogeneous insoluble materials. While homogeneous catalysts are typically very active and selective, they are difficult to recover. Conversely, heterogeneous catalysts are easy to recover and reuse, but they generally are less selective. To address these issues, the immobilization of homogeneous catalyst analogs onto solid supports has been a subject of research for the past few decades. Nonetheless, the effects of immobilization are still not completely predictable, and so continued effort is required to develop new immobilized catalysts as well as to develop a better understanding of how different parameters affect catalytic behavior. This dissertation presents the synthesis, characterization, and evaluation of new immobilized catalysts for different applications. First, a solid base catalyst supported on silica was developed and studied in the synthesis of cyclic carbonates from epoxides and carbon dioxide. Next, polymer and silica supported vanadium Schiff base catalysts were developed and evaluated for use in the oxidative kinetic resolution of alpha-hydroxy esters, an enantioselective reaction. Lastly, salen catalyst analogs with amine reactive functional groups were synthesized and characterized for grafting onto aminosilicas with different degrees of amine group isolation. The grafted catalysts were then tested to determine how catalyst spacing on the surface affects their behavior. Throughout the presentation of these results, comparisons are made amongst the new supported catalysts and relevant existing catalysts to discern general trends which could be applied to a wider range of immobilized catalysts. Finally, research opportunities for further improvements in these areas are suggested.
Author: Alyssa Marie Love
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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The structure of metal oxide sites on supported metal oxide catalysts has a significant impact on the performance of the catalyst. For example, silica-supported vanadium oxide-a catalyst widely studied for the oxidative dehydrogenation of propane (ODHP) to propene-has a higher selectivity towards propene when the catalyst surface is comprised of primarily dispersed VOx surface species. Conversely, as the loading of vanadium oxide is increased beyond the monolayer coverage threshold, three-dimensional V2O5 particles begin to form which lower the catalyst selectivity towards propene (at higher propane conversions) in favor of COx combustion products. For this catalytic application and for other supported metal oxides, understanding the variables that maximize the dispersion of two-dimensional metal oxide species on a support surface is invaluable information to improve the preparation of these catalysts. This thesis describes the synthesis and detailed characterization of supported oxide catalysts for the oxidative dehydrogenation of catalysts. In this work, vapor-phase grafting techniques were used to investigate the chemical reactions that occur during the synthesis of silica-supported vanadium oxide ODH catalysts. By depositing the neat vanadium precursor, VO(OiPr)3, onto silica dehydrated at 700 degrees C (called V/SiO2(700)), the complexity of variables in the synthesis was significantly decreased (compared to incipient wetness). Key anchoring and restructuring reactions during the formation of vanadium oxide sites on silica were characterized with a combination of infrared (IR), Raman, solid-state nuclear magnetic resonance (NMR), and X-Ray absorption spectroscopic studies, in addition to thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS), inductively coupled plasma (ICP) elemental analysis, etc. Afterwards, key synthesis variables (i.e., isopropanol solvent, H-bonded silanols and Na+ ions on the support surface) were incorporated into this grafting system to develop a more comprehensive model for the dispersion of vanadium oxide under wet impregnation conditions. Efforts to improve Raman sensitivity towards metal oxide surface sites with shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) are also addressed in this work. The methodology and characterization approach presented for the study of supported vanadium oxide catalysts was also applied to the study of promising new ODHP catalysts, including hexagonal boron nitride and silica-supported boron oxide catalysts.
Author: Pankajkumar P. Sancheti
Publisher:
ISBN:
Category : Biodiesel fuels
Languages : en
Pages : 266
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