CO oxidation over CuO catalysts prepared with different precipitants

CuO catalysts, prepared by the precipitation method using different precipitants such as ammonium hydroxide, sodium hydroxide, sodium carbonate and sodium hydrogen carbonate were applied to CO oxidation. Among the catalysts studied, CuO synthesized with sodium hydrogen carbonate showed the highest activity for CO oxidation. With the water vapor present in the feed gas, the catalytic activity decreased considerably due to reduction in the number of active sites by competitive adsorption between water vapor and CO. The H-2-TPR and CO-TPD results showed that existing Na+ cations and HCO3- and CO32- anions on the CuO surface could weaken the copper-oxygen bond strength and accelerate the mobility of oxygen on the surface or lattice. Finally, the morphology of the CuO crystals was dependent on the precipitants, and the introduction of Na+ cations and various anions resulted in the formation of smaller crystals.