Role of Pd and Cu in gas-phase alcohols photocatalytic degradation with doped TiO2

Propan-1-ol and butan-1-ol photo-degradation with TiO2 (bare-TiO2) and TiO2 doped with Pd or Cu has been studied in a gaseous continuous flow system. Exhaust gases have been analysed by means of GC and FTIR. During propan-1-ol and butan-1-ol degradations, catalysts were not deactivated. Nevertheless, important differences in concentrations and distributions of intermediates were obtained, depending on the catalyst studied. These alcohols interactions with TiO2 surface give alcoholates. However, their interactions with Pd-TiO2 and Cu-TiO2 do not yield alcoholates. Doped catalysts have progressively grown dark during the experiments, especially when N-2 atmospheres were used. This colour change may be given by the reduction of metal oxides deposited on the catalyst surface. These different photocatalytic behaviours may be explained by means of the alcoholate interaction with the catalysts surfaces, their ability to scavenge photogenerated electrons and react with radicals formed from propan-1-ol and butan-1-ol. (C) 2005 Elsevier B.V. All rights reserved.