Adsorption and reaction of CO on CuO-CeO2 catalysts prepared by the combustion method

Temperature-programmed techniques were employed to investigate the interaction of CO with CuO-CeO2 prepared by the urea-nitrates combustion method. These catalysts exhibited high and stable CO oxidation activity at relatively low reaction temperatures (< 150 degrees C). The CO adsorption capacity and catalytic activity of the catalysts was analogous to the concentration of easily-reduced copper oxide surface species. TPD and TPSR results can be explained by a dual scheme of CO adsorption: (i) on oxidized sites, which get reduced with simultaneous formation of surface CO2 and (ii) on reduced sites created by the former interaction. 10-20% of adsorbed CO desorbs molecularly in the absence of gas-phase O-2, but reacts totally towards CO2 in the presence of gas-phase O-2. Inhibition by CO2 observed under steady-state CO oxidation conditions is due to CO2 adsorption as found by CO2-TPD.