Preferential oxidation of CO in H2-rich stream over CuO/Ce1−xTixO2 catalysts

Abstract

CuO/Ce1−xTixO2 prepared by sol–gel impregnation was used as catalysts for the preferential oxidation (PROX) of CO in H2-rich stream. The effects of support composition, catalyst calcination temperature as well as the presence of H2O and CO2 in the reaction stream on the catalytic performance of CuO/Ce1−xTixO2 were investigated. The results indicated that the catalyst CuO/Ce0.8Ti0.2O2 exhibits the highest activity and the optimal temperature for the catalyst calcination is 500°C. The presence of H2O and CO2 in the reaction stream has a negative effect on the catalytic activity and stability of CuO/Ce0.8Ti0.2O2. The negative effect of CO2 on the catalyst stability is stronger than that of H2O, suggesting that the accumulation of carbonate species may be the main reason for catalyst deactivation. The characterization by means of XRD, HRTEM, and H2-TPR indicated that the doping of TiO2 in CeO2 enhances the surface area of the composite oxide support, decreases its particle size, and promotes the dispersion of active copper species. The strong interaction between TiO2 and CeO2 in the support as well as the interfacial interaction between CuO and the support may also contribute to the high catalytic activity of CuO/Ce0.8Ti0.2O2.