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dc.contributor.advisorRichards, Ryan
dc.contributor.authorWang, Xue
dc.date.accessioned2007-01-03T05:35:06Z
dc.date.accessioned2022-02-09T08:51:41Z
dc.date.available2007-01-03T05:35:06Z
dc.date.available2022-02-09T08:51:41Z
dc.date.issued2013
dc.identifierT 7203
dc.identifier.urihttps://hdl.handle.net/11124/79358
dc.description2013 Spring.
dc.descriptionIncludes illustrations (some color).
dc.descriptionIncludes bibliographical references.
dc.description.abstractNanoscale metals or metal oxides with high surface area to volume ratios have been widely used as catalysts for various chemical reactions. A major challenge to utilize metal nanocatalysts commercially is their tendency to sinter under working reaction conditions. To overcome this, much research is being done to anchor metal nanocatalysts on various supports to prevent their agglomeration. Mesoporous silica, SBA-15 is an attractive support material candidate because of its high surface area, stable structure and chemical inertness. Scientists have anchored metal nanocatalysts onto the pore of SBA-15 and observed some improvement in the stability. However, the interactions between the nanocatalysts and SBA-15 are relatively weak and sintering still occurs resulting in a loss of activity. In order to impart enhanced robustness, a new type of stable metal/SBA-15 nanocomposite has been prepared by intercalating metal nanoparticles into the walls of mesoporous silica SBA-15 by a unique synthetic strategy using metal coordinating agents such as bis[3-(triethoxysilyl) propyl]-tetrasulfide (TESPTS). In this dissertation, systemic research on the preparation parameters and extension to other metals will be presented. The structure changes caused by addition of TESPTS to the preparation of mesoporous silica were investigated. The relationship between increasing amounts of TESPTS and the structural change was obtained. Afterwards, a new type of PdMS catalyst with Pd intercalated in the walls of SBA-15 was synthesized for the first time using a modified preparation pathway. These materials were characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy and inductively coupled plasma. The PdMS system was utilized as an active and robust catalyst for Heck reactions. Notably, after the catalytic reaction, the PdMS catalysts maintained its reactivity and size without undergoing any agglomeration due to the stable nanocomposite structure. Carbon disulfide (CS2) was used to poison the catalyst to determine the relative number of active sites for the reduction of 4-nitrophenol. Moreover, the novel PdMS catalyst is recyclable and shows excellent stability after exposure to elevated temperatures. Additional, tentative PtMS and AgMS are synthesized based on the PdMS protocol. Besides, shape-controlled Pd nanocrystals are prepared aiming at to be intercalated into the wall of mesoporous silica and used as catalysts with certain selectivity.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2010-2019 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subject.lcshNanotechnology
dc.subject.lcshNanoparticles
dc.subject.lcshMetallic oxides
dc.subject.lcshCatalysts
dc.subject.lcshMesoporous materials
dc.titleSynthesis, characterization and catalytic application of nanoscale metal and metal oxide heterogeneous catalysts
dc.typeText
dc.contributor.committeememberCiobanu, Cristian V.
dc.contributor.committeememberWilliams, S. Kim R.
dc.contributor.committeememberPosewitz, Matthew C.
dc.contributor.committeememberTrewyn, Brian
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineChemistry and Geochemistry
thesis.degree.grantorColorado School of Mines


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