Forecasting selectivity of Au-based partial oxidation catalysts via temperature programmed desorption studies on the Au(111) model catalyst

buir.advisorÖzensoy, Emrah
dc.contributor.authorShah, Syed Asad Ali
dc.departmentDepartment of Chemistryen_US
dc.descriptionIncludes bibliographical references (leaves 81-86).en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionThesis (M.S.): Bilkent University, The Department of Chemistry and the Graduate School of Engineering and Science of Bilkent University, 2014.en_US
dc.description.abstractGold-based heterogeneous catalysts have attracted significant attention due to their selective partial oxidation capabilities which are comparable to that of the industrial homogeneous benchmark catalysts. In the current study, a planar Au(111) single crystal model catalyst surface was utilized to understand the behavior of different organic compounds (alcohols, aldehydes, esters etc.) in conjunction to the partial oxidation reactions. Stability of different organic compounds were investigated on the Clean Au(III) surface. The stability of a particular organic compound on the Au(III) model catalyst surface was found to be closely related to the variety of generated products. Surface sensitive analytical techniques such as Temperature Programmed Desorption (TPD) and Low Energy Electron Diffraction (LEED) were used to investigate the interaction of organic compounds with the clean Au(111) single crystal surfaces under ultrahigh vacuum (UHV) conditions. Organic compounds were dosed onto atomically clean Au(III) surfaces at the liquid nitrogen temperature. All organic compounds desorbed non-dissociatively on the clean Au(111) surface. All organic compounds reveal monolayer and multilayer desorption signals but in the case of aldehydes, desorption is quite different, as they lead to polymerization on the surface with high desorption temperatures. Zeroth order desorption kinetics was observed for multilayers, while 1st order desorption was seen for the monolayer. In most cases, the multilayer feature can be observed with two distinct desorption peaks associated with amorphous and crystalline phases. In this work, it is confirmed that majority of the studied compounds have relatively low adsorption energies on Au(111). The species with lower desorption energies on Au(111) tend to undergo partial oxidation rather than total oxidation. Thus, desorption energy appears as an important descriptor for predicting the extent of oxidation in partial/total oxidation in oxidative coupling reactions.en_US
dc.description.statementofresponsibilityby Shah, Syed Asad Ali.en_US
dc.format.extent86 leaves : charts, plates.en_US
dc.publisherBilkent Universityen_US
dc.subject.lccQD505 .S53 2014en_US
dc.titleForecasting selectivity of Au-based partial oxidation catalysts via temperature programmed desorption studies on the Au(111) model catalysten_US
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