The gas-phase photocatalytic mineralization of benzene on porous titania-based catalysts

Abstract

Photocatalytic degradation of benzene in oxygen-containing gaseous feed streams was investigated using titania and platinized (0.1 wt.-%) titania photocatalysts. The titania catalyst was synthesized using sol-gel techniques. Results of this study indicate that, when using this particular photocatalyst, benzene was oxidized to carbon dioxide and water without forming any detectable organic reaction products in the reactor effluent, although only some of the benzene reacted. Both the overall conversion of benzene and its mineralization were improved by platinizing the titania. When the titania catalyst was platinized, both photocatalytic and thermocatalytic reactions were promoted. Rates of photocatalytic reactions were significantly enhanced at reaction temperatures between 70 and 90°C, while at temperatures above 90°C the rates of thermocatalytic oxidation reactions were noticeably increased. It proved possible to obtain the continuous and essentially complete mineralization of benzene by using the platinized titania catalyst and optimizing such parameters as the reaction temperature, space time, and the concentrations of oxygen and water vapor in the feed stream.