CO oxidation on planar Au/TiO2 model catalysts: Deactivation and the influence of water

The CO oxidation behaviour of planar Au/TiO2 model catalysts was studied by a combination of kinetic measurements and in-situ IR measurements under realistic pressure and temperature conditions (p = 20 mbar, T = 80 °C). During reaction in a CO/O2 mixture, the model catalysts deactivated significantly. Adding small amounts of H2O (1000 ppm) to the reactive CO/O2 gas mixture, the catalyst activity increased markedly, by at least one order of magnitude. Furthermore, in-situ IR measurements show a decrease of the amount of adsorbed by-products of the CO oxidation, and a change of the predominant by-product from surface carbonate to surface formate. Possible reasons for the deactivation are discussed and the effect of H2O addition is compared to results of similar studies on more realistic dispersed catalysts.