Performance of doped Pt/TiO2 (W6+) catalysts for combustion of volatile organic compounds (VOCs)

The oxidation of benzene and ethylacetate, present in trace amounts in air, over Pt supported on gamma-Al2O3, SiO2, TiO2 and TiO2 (W6+) carriers has been studied. It was found that doping of the TiO2 support with W6+ cations has a positive effect on the activity of Pt catalysts for benzene and ethylacetate oxidation. A maximum in activity enhancement has been observed at a W6+ content of 0.45 at% in the TiO2 support. The Pt/TiO2 (0.45 at% W6+) catalyst is over two orders of magnitude more active than the Pt/gamma-Al2O3 catalyst in the case of ethylacetate oxidation and an order of magnitude more active in the case of benzene oxidation. Doping of TiO2 with W6+ cations enhances its activity for ethylacetate degradation towards smaller organic intermediates, such as ethanol, acetic acid and ethylene, and it also affects product distribution. The enhanced activity of the Pt/TiO2 (W6+) catalysts is attributed to complementary bifunctional steps occuring on sites offered by Pt metal and by the support. During oxidation of benzene-ethylacetate-water mixtures, benzene oxidation is strongly suppressed in the presence of ethylacetate, while water acts as an inhibitor for both volatile organic compounds (VOC) oxidations. (C) 1998 Elsevier Science B.V.