(536a) S Doped TiO2 for Photocatalytic Oxidation of CO in Visible Region Synthesized By Novel One Step Liquid Flame Spray Pyrolysis (LFSP): Kinetics and Mechanism

Inturi, S. N. R., University of Cincinnati
Smirniotis, P., University of Cincinnati
A novel single step Liquid Spray pyrolysis (LFSP) method is used to synthesize a series of S-TiO2 catalyst of nanosized crystals with dimensional homogeneity and high monodispersity. A series of S-TiO2 catalyst of nanosized crystals with high monodispersity and dimensional homogeneity are synthesized by using the novel single step Liquid Spray pyrolysis (LFSP) method. Different quantities of S was incorporated into TiO2 catalyst, which is beneficial to the generation of the successive energy bands inside the TiO2 band gap. Our XPS results indicate that the S doping concentration could reach to 8 wt% owing to the homogeneous doping in the mesoporous TiO2 catalysts. The S doped TiO2 catalyst exhibit such excellent characteristics as high specific area, relatively small particle size, pure anatase phase and excellent UV-vis absorption capacity in the range of 400-800 nm, which are all beneficial to the photocatalytic oxidation of CO under the visible light irradiation. The photo conversion of CO to CO2 is quantitative in the presence of O2. The photocatalytic CO oxidation rates and the amounts of S deposited on TiO2 surface show a close correlation. The CO photooxidation is strongly inhibited in the absence of O2 or in the presence of alternative oxidants such as N2O and H2O. The addition of water vapor little affects the CO photooxidation kinetics in the presence of O2. Hydroxyl radicals do not seem to play a significant role in CO photooxidation on S-TiO2. The photocatalytic oxidation kinetics was investigated in detail as a function of S loading, coated TiO2 mass, CO concentration, O2 concentration, light intensity, additives, and humidity.