Mesoporous TiO2-based photocatalysts for UV and visible light gas-phase toluene degradation

UV and visible light photocatalytic removal of concentrated toluene (110 ppm) in the gas phase was performed in an annular flow-reactor on mesoporous anatase TiO2 supported WO3 photocatalysts. Depending on the template, hexagonal and cubic mesoporous TiO2 thin layers were obtained by dip-coating of an anatase sol onto slides of soda lime–silica glass, which was then mechanically removed. The coupling of low contents of WO3 (4 wt.%) with mesoporous anatase TiO2 led to high photocatalytic efficiency both using UV and visible light activation. The highly positive effect of WO3 on the toluene removal efficiency was attributed to a one-way and a two-way coupling phenomena depending on the photocatalyst nature and on the activation source. The hypothesis of a confinement effect of the reactants inside the mesoporous structure, based on an increase in their partial pressure on the active sites, was put forward to explain the high photocatalytic performances obtained under UV and visible light activation.