Photocatalytic oxidation of butyl acetate in vapor phase on TiO 2, Pt/TiO 2 and WO 3/TiO 2 catalysts

Abstract

The photocatalytic degradation of butyl acetate in the gas phase was investigated in a fixed-bed continuous annular reactor using a titanium dioxide semiconductor, Pt/TiO 2 and WO 3/TiO 2 catalysts. Platinum was deposited on the titanium by adsorption of PtCl 6 2− anions, and WO 3/TiO 2 was prepared by a conventional impregnation method using an aqueous solution of ammonium paratungstate. Different samples, with different nominal weight loadings in Pt and WO 3, were tested. For each catalyst sample studied, air containing butyl acetate and water vapors in various molar ratios was fed at 200 cm 3/min to the photoreactor. The roles of the reaction temperature and of H 2O in the photocatalytic oxidation of butyl acetate and the influence of the content of TiO 2, Pt, and WO 3 were investigated. Although an initial decay in photocatalytic activity was observed, partly issued from an initial deactivation, total mineralization was achieved under all experimental conditions. For relative water humidity between 50 and 75% and for adequate TiO 2 covering ratios, the photocatalytic activity of TiO 2 toward the photocatalytic degradation of butyl acetate can be greatly improved by the addition of WO 3, mainly due to a prevention of the initial deactivation and of photogenerated charge recombination. This optimized photocatalyst is very stable on stream and no regeneration treatments are needed. The influence of Pt and WO 3 on photocatalytic activity are discussed with regard to chemical and electronic modifications of TiO 2.