The selective and nonselective oxidation of propane was investigated using a range of metal oxide catalysts. Total oxidation of propane was studied using Nb and W supported on Pd/Ti02- The addition of Nb or W to Pd/TiO<sub> 2</sub> promoted the activity of the catalyst to give 100% conversion by 450°C. The only reaction product observed was carbon dioxide. The addition of Nb and W significantly changed the nature of the palladium and oxygen mobility, from XPS studies. Niobium and tungsten exhibited the highest activity with a 6% loading with the best catalyst being 0.5%Pd/6%Nb<sub>2</sub>O<sub>5</sub>/TiO<sub> 2</sub>. Oxidative dehydrogenation of propane was studied using vanadium on a ceria support and also with cobalt, iron and manganese oxides. Ceria on its own was very active for the total oxidation of propane, under the conditions used for oxidative dehydrogenation, but the sole reaction product was carbon dioxide. The addition of vanadium switched the activity of the ceria to give appreciable selectivity to propene of around 90%. The formation of a mixed cerium vanadium phase was of the most interest for future work where conditions could be optimised to give improved yields. Cobalt, iron and manganese oxides were prepared by grinding the corresponding nitrate with ammonium bicarbonate and their activity tested in propane oxidative dehydrogenation. The yields of propene were higher than the V/CeO<sub>2</sub> catalysts with the most active oxide being cobalt with a yield of 3.8%. The activity of cobalt was attributed to a small crystallite size, high reducibility and high ratio of O/Co. Methanol oxidation was also investigated using the cobalt, iron and manganese oxides. The main reaction product was formaldehyde and the highest yield, of 23%, was obtained for the manganese oxide. The activity was attributed to a high O/Mn ratio of 3.03 and an optimal particle size of 54nm.
Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:584941 |
Date | January 2010 |
Creators | Gilmour, Marie Naomi |
Publisher | Cardiff University |
Source Sets | Ethos UK |
Detected Language | English |
Type | Electronic Thesis or Dissertation |
Source | http://orca.cf.ac.uk/54964/ |
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