Preparation and high catalytic performance of Co3O4–MnO2 for the combustion of o-xylene

Abstract

The xCo3O4–MnO2 (x = 2.6, 8.8, and 13.3 wt%) catalysts were prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and acid treatment methods. Physicochemical properties of the samples were characterized by means of various techniques. Catalytic performance of the xCo3O4–MnO2 samples was evaluated for the combustion of o-xylene. It is shown that the as-prepared samples possessed a cubic crystal structure and a surface area of 51.9–63.9 m2/g. The 8.8Co3O4–MnO2 sample possessed the highest adsorbed oxygen species concentration and the best low-temperature reducibility, and hence performing the best: the T10%, T50%, and T90% (temperatures required for achieving o-xylene conversion of 10, 50, and 90%, respectively) were 231, 251, and 273 °C at a space velocity of 100,000 mL/(g h). The apparent activation energies obtained over the xCo3O4–MnO2 catalysts for o-xylene combustion were 72–82 kJ/mol. The effects of space velocity, water vapor, and carbon dioxide on the catalytic activity of the 8.8Co3O4–MnO2 sample were also examined, and the partial deactivation due to water vapor and carbon dioxide introduction was reversible. It is concluded that the good catalytic performance of 8.8Co3O4–MnO2 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Co3O4 and MnO2.