Gas-phase photo-oxidation of toluene using nanometer-size TiO2 catalysts

A modified sol-gel process was used to prepare nanostructured TiO2 catalyst s of controlled particle size (i.e. 6, 11, 16 and 20 nm). The influence of the TiO2 particle size in the gas phase photocatalytic oxidation of toluene was investigated under both dry and humid conditions. The main products of reaction were carbon dioxide and water, although small amounts of benzalde hyde were also detected. The smaller particle size (i.e. 6 fim) lead to hig her conversion and complete mineralization of toluene into CO2 and H2O. Bot h electronic and structural effects (i.e. size and ensemble effects) are re sponsible for the excellent performance of 6 nm TiO2 catalyst for toluene p hoto-degradation. The structural differences between 6 nm TiO2 and larger c atalysts were analyzed using EPR spectroscopy. (C) 2001 Elsevier Science B. V. All rights reserved.