3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Direct methane transformation into higher hydrocarbons and oxy-products(1996) Eskendirov, IgorIn present thesis the results of a study of the combined action of a solid catalyst and a gas-phase inintiator, hydrogen peroxide, in the methane partial oxidation and oxidative coupling reactions are presented. [Abbreviated Abstract. Open document to view full version]Item An ethanol conversion study over titania supported catalysts(1992) Chen, Yao-KuanThe ethanol conversion to hydrocarbons over acidic catalysts proceeds with high activity and selectivity and has hence generated considerable interest. In this thesis an investigation of the use of a range of supports, loaded with metals as potential catalysts for the ethanol transformation reaction, is reported. In particular, Ti02 was investigated as a support and the addition of a secondary component to the catalyst was examined with respect to product selectivities. [Abbreviated Abstract. Open document to view full version]Item An invesigation of the physical and chemical changes occuring in a Fischer-Tropsch fixed bed catalyst during hydrocarbon synthesis(1990) Duvenhage, Dawid JakobusDeactivation studies; making use of fixed bed reactors, wet chemical analysis, surface area, pore volume determinations and X-ray diffraction—, scanning electron microscope— and secondary ion mass spectrometry techniques; were performed on a low temperature iron Fischer—Tropsch catalyst. It was revealed that this catalyst is mainly deactivated by sulphur poisoning, oxidation of the catalytic reactive phases, sintering of the iron crystallites and to a lesser extent deactivation through fouling of the catalytic surface by carbonaceous deposits. It was found that the top entry section of the catalyst bed deactivated relatively fast, the bottom exit section also deactivated, but not as fast as the top section The central portion of the catalyst bed was least affected. Sulphur contaminants in the feed gas, even though present in only minute quantities, results in a loss of catalyst performance of the top section of the catalyst bed, while water, produced as a product from the Fischer—Tropsch reaction, oxidized and sintered the catalyst over the bottom section of the catalyst bed.