The oxidation of benzyl alcohol over supported gold, palladium and gold palladium catalysts was studied in a high-pressure stirred autoclave. Reaction conditions such as oxygen pressure and reaction temperature were varied to obtain optimum conditions for catalyst screening. Gold palladium catalysts supported on various oxides were prepared and screened with titania supported catalysts proving to be the most active. Different preparation methodologies were used to prepare titania supported bi-metallic catalysts, co-deposition precipitation methodology was found to give the most active and stable catalyst. Further gold, palladium and gold palladium catalysts were prepared supported on ceria that had been obtained from the calcination of cerium acetylacetate that had been precipitated into a supercritical carbon dioxide antisolvent. These catalysts proved to be significantly more active than those supported on the ceria form the simple calcination of the precursor. Reuse experiments showed that the supercritically prepared ceria precursor catalyst increased in activity with use, despite significant leaching of the metals, an effect not observed for the non-supercritically prepared ceria precursor catalyst. The ceria catalysts prepared by the supercritical antisolvent method displayed very high turn over frequencies for the oxidation of l-octen-3-ol, 2-octen-l-ol and cinnamyl alcohol. Gold and gold palladium catalysts supported on titania and graphite were used for the oxidation of 2,5-dimethyl furan to form hex-3-ene-2,5-dione. The effect of temperature, pressure and radical initiator were investigated and the highest selectivity was achieved at the lowest oxygen pressure. The oxidation of a-pinene to verbenone investigated, the reaction proceeded with highest conversion at high oxygen pressure with catalyst not required for the reaction to proceed. Gold palladium catalysts were used for the oxidation of isophorone and valencene using the optimized conditions established for the a-pinene reaction system. 2,6-lutidene, 2-picoline and 3-picoline were found to be poisons for gold palladium catalysts.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:584613 |
| Date | January 2009 |
| Creators | Miedziak, Peter |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/54878/ |
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