Influence of pretreatment conditions on low-temperature carbon monoxide oxidation over CeO2/Co3O4 catalysts Original Research Article

The modification of ceria (CeO2) on high surface area cobaltic oxide (Co3O4) and the promotion effect of CO oxidation via different pretreatment conditions were studied. The high-valence cobalt oxide was prepared first by precipitation-oxidation in ice bath, followed by reduction at 230 °C to get pure and high surface area cobaltic oxide (assigned as R230, SBET = 100 m2 g−1). Further, the Ce20/R230 catalyst was prepared by impregnation with cerium nitrate (20% cerium loading). Pretreatment of Ce20/R230 catalyst was divided into two methods: reduction (under 200 and 400 °C) and calcination (under 350 and 550 °C). The catalysts were characterized by X-ray diffraction (XRD), infrared (IR), and diffuse reflectance spectroscopy (DRS), and temperature-programmed reduction (TPR) and by nitrogen adsorption at −196 °C. The results showed that pretreatment under low-temperatures obtained both larger surface area and better activity. The Ce20/R230-H200 catalyst exhibited the highest surface area (SBET = 109 m2 g−1) and the best catalytic activity in CO oxidation with T50 (50% conversion) at 88 °C among series of catalysts due to the combined effect of cobaltic oxide and ceria. The optimized pretreatment of CeO2/Co3O4 catalysts can clearly enhance the catalytic activity.