Selective CO oxidation over silver cobalt composite oxide catalysts

Abstract

            The removal of CO containing in the reformed gas to ppm level has been extensively studied via selective CO oxidation method. This method is useful for fuel cell applications because the trace amount of CO containing in the reformed gas poisons the Pt anode at the electrode of PEM fuel cells. This leads to the lowers of the fuel cell efficiency. In this study, the activity of silver cobalt composite oxides as a catalyst to CO oxidation and selective CO oxidation in the simulated reformed gas were reported. It was found that the molar ratios of silver to cobalt of 1 to 3 and 1 to 5 were very active to CO oxidation at low temperatures (<50oC). These catalysts to selective CO oxidation were further investigated. The optimal O2 concentration that added into the gas stream was 3%. It was also found that the presence of H2O increased CO conversion but slightly changed selectivity to CO oxidation. Finally, the stability and the deactivation process were tested. It was shown that this catalyst was deactivated when methane formation occurred. The deactivation is an irreversible process due to carbon deposition.