| Summary: | 碩士 === 國立中正大學 === 化學工程研究所 === 93 === Wet air oxidation (WAO) is a liquid-phase reaction between organic material in water and oxygen. The WAO process is used around the world to treat industrial wastewaters, at higher temperatures (473-623K), and at pressures from 5 to 23 MPa. The efficiency of aqueous phase oxidation can be largely improved by the use of catalysts. Active carbons are normally used as catalyst supported for WAO because of their high adsorption capacity of organic compound, high acid resistance, and easily tailored surface properties. However, catalytic oxidative combustion of active carbon by metal clusters deposited on carbon will change the surface property thereby motivate metal aggregation resulting in a quick catalyst deactivation. In order to remedy the drawbacks, TiO2 were grafted on active carbon to suppress metal aggregation by anchoring the metal clusters on TiO2. Ti(OEt)4 were chosen as TiO2 precursor. The Ti precursors were grafted on the active carbon via dehydration condensation reaction. Further thermal treatment in inert gas environment decomposes the Ti ligands and TiO2 tetrahedral entities were formed on the surface. The resulting material was characterized by FT-IR, TPO and TGA and the results indicated that the grafted TiO2 couldn't increase the extent of anti-oxidation. On the other hand, the carbon supports burning rate was speeded up catalytically by the grafted TiO2. Because of this limitation, the reaction catalyzed by Pt/ TiO2-C catalysts was suggested to be carried out at moderate reaction temperature, namely, less than 200 C. Under such circumstance, the Pt/ TiO2-C presents much superior catalytic performance than do Pt/C catalysts. TEM and EXFAS indicated that Pt clusters on TiO2-C keep the similar morphology after reaction in contrast to the growth of Pt clusters being observed for the Pt/C samples. The effective suppression of Pt aggregation may be caused by anchoring of Pt clusters on the TiO2 .
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