In this thesis, a range of TiO2-based photocatalysts and cobalt-based Fischer-Tropsch (FT) catalysts were developed and synthesised via the one-step Flame Spray Pyrolysis(FSP). The work starts with the demonstration of bare TiO2 nanoparticles synthesis with controlled characteristics such as specific surface areas, crystallite sizes and anatase content. A comparative study was carried out by benchmarking with commercial Degussa P25 TiO2. The FSP TiO2 was shown to be more efficient in mineralising pollutants requiring direct charge transfer such as the saccharides, while P25 was better for mineralising alcoholic and aromatic compounds. Both catalysts were equally as active in mineralising carboxylic acids. Upon identifying the optimal synthesis of bare TiO2, an in situ co-precipitation of highly dispersed Pt on TiO2 was carried out in the flame. Deposition of Pt resulted in enhanced photocatalytic performance as a result of efficient charge trappings. It is highlighted here the inter-relationship between Pt oxidation states and the TiO2photocatalysis of carboxylic acid, alcohol and aromatic compounds. Depending on the mineralisation path adopted by the model organic compounds, they were shown to have direct influence on the Pt oxidation states. These oxidation states in turn affect the mineralisation rates of the organic compounds. Substitutional-doping of TiO2 with Fe(III) with tunable bandgap was also possible by FSP synthesis. The high temperature synthesis coupled with rapid quenching resulted in 5 times higher solubility limit (Fe/Ti = 0.05) than that previously reported in the literature. Under visible light irradiation, FSP-made Fe-TiO2 improved the photocatalytic mineralisation of oxalic acid by more than 6 times, with respect to P25 and FSP TiO2. Furthermore, the photocatalyst was reusable over a number of repetitions with minimal leaching or loss in activity. The last part of the work concerns the development of bare and Ru-doped Co-ZrO2 catalysts, where cobalt was finely dispersed within the zirconia matrix. Doping of Ru enhanced significantly the reducibility of cobalt, reducing even the embedded cobalt beneath the zirconia surface. It also increased the extent of CO-chemisorption and as such, enhanced the FT activity. This is the first time, catalysts of such type is synthesised and tested for FT reaction.
| Identifer | oai:union.ndltd.org:ADTP/243108 |
| Date | January 2007 |
| Creators | Teoh, Wey Yang, Chemical Sciences & Engineering, Faculty of Engineering, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Chemical Sciences and Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Wey Yang Teoh, http://unsworks.unsw.edu.au/copyright |
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