An investigation of trichloroethylene photocatalytic oxidation on mesoporous titania-silica aerogel catalysts

Abstract: Freestanding blocks of mesoporous, titania-silica aerogel catalyst were prepared and tested for gas phase photocatalytic oxidation of trichloroethylene (TCE) in a new photoreactor where the reactant gases flow through the aerogel block. The intimate contact between the reactants and catalyst resulted in a higher conversion. TS01 aerogel was prepared by ethanol supercritical drying, and contained nanometer-sized crystalline domains of anatase TiO2 (i.e., Tih name="sbnd" />Ti sites) within an amorphous Sih name="sbnd" />Ti and Sih name="sbnd" />Si network. The TS02 aerogel prepared by CO2 supercritical drying remained amorphous even after high temperature treatment, and analysis indicated that the Tih name="sbnd" />Si is the predominant site on this catalyst. The reaction results indicated that only the TS01 aerogel containing anatase TiO2 was active, but the formation of dichloroacetaldehyde on the amorphous Sih name="sbnd" />Si sites led to a rapid catalyst deactivation. However, a stable catalyst was obtained after these sites were passivated by ozone pretreatment under ultraviolet (UV) irradiation. The TS01 aerogel catalysts exhibited an average conversion of 30% and a quantum yield of 0.27 at a TCE concentration of 56ppm, feed flow rate of 40sccm and UV irradiation of 710μWcm−2. [Copyright &y& Elsevier]