Origin of the High Activity and Stability of Co3O4 in Low-temperature CO Oxidation

In this paper, the Co3O4 catalysts prepared by the liquid phase precipitation method were investigated with respect to their activity and stability in CO oxidation reaction. The Co3O4 catalysts were comparatively investigated by thermal gravimetry analysis (TG-DTG), X-ray powder diffraction (XRD), N2 adsorption, CO titration and O2-temperature program desorption (O2-TPD). The results of XRD show that all the catalysts exist as a pure Co3O4 phase with the spinel structure. The high catalytic activity observed at ambient temperature is followed by a gradual decrease. The CO titration experiments show that the Co3O4 catalysts possess active oxygen species. The total amount of active oxygen species and the specific surface area decrease with increasing calcination temperature. The O2-TPD results indicate that O2− and O− are the possible active oxygen species.