Degree Type

Dissertation

Date of Award

1992

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Bernard C. Gerstein

Abstract

Solid-state NMR has been used to study the interaction of ethylene with oxygen in the absence of promoters and moderators over silica-supported silver catalysts. Experiments using nitrous oxide and oxygen as the oxidants have been carried out over Ag/SiO[subscript]2 catalysts at temperature ranging from 298 to 613 K. Standard cross-polarization with magic angle spinning (CP/MAS), CP/MAS with dipolar dephasing, and single-pulse experiments have been applied to identify carbon containing species that are formed on the surface of catalyst at various temperatures. Ethylene, acetic acid, carbon dioxide, ethane and an alkoxy species have been identified. Under the above experimental conditions, no ethylene oxide is detected by NMR. In pursuit of a better understanding of the chemistry taking place on the catalyst, silica-supported silver catalysts as well as pure silica were dosed with labeled ethylene, carbon dioxide and ethylene oxide. It was found that under conditions employed in this study, ethylene oxide reacts with both metal and silica support and thus can not be observed as the reaction product. Ethylene oxide, however, has been observed after the saturation of silica surface with unlabeled ethylene oxide prior to ethylene oxidation.;In conjunction with this project, the author has designed and constructed a multiport high vacuum glass apparatus which was used for sample preparation prior to the NMR experiments as well as chemisorption measurements and a single-coil double resonance probe.

DOI

https://doi.org/10.31274/rtd-180813-12557

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Sadreddin Hosseini

Language

en

Proquest ID

AAI9234817

File Format

application/pdf

File Size

123 pages

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