Photoassisted Catalytic Oxidation of Carbon Monoxide at Room Temperature

The thermal and photoassisted catalytic oxidation of CO at metal oxide supported RuO2·xH2O was studied at room temperature. Contrary to neat RuO2·xH2O the supported catalysts suffer from fast deactivation attributed to strong adsorption of the reaction product carbon dioxide. The latter can be efficiently removed from the catalyst surface at elevated temperatures. In some cases, i.e. for catalysts supported with selected n-type semiconductors (TiO2, SnO2, WO3), efficient CO2 desorption and good, constant catalytic activity was observed upon visible light irradiation. Under such conditions the CO to CO2 conversion observed for RuO2·xH2O/TiO2 was nearly as good and stable as for the unsupported catalyst. It is suggested that light absorption promotes carbon dioxide desorption through positive charging of the catalyst surface.