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

In this paper, the Co 3 O 4 catalysts prepared by the liquid phase precipitation method were investigated with respect to their activity and stability in CO oxidation reaction. The Co 3 O 4 catalysts were comparatively investigated by thermal gravimetry analysis (TG-DTG), X-ray powder diffraction (XRD), N 2 adsorption, CO titration and O 2 -temperature program desorption (O 2 -TPD). The results of XRD show that all the catalysts exist as a pure Co 3 O 4 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 Co 3 O 4 catalysts possess active oxygen species. The total amount of active oxygen species and the specific surface area decrease with increasing calcination temperature. The O 2 -TPD results indicate that O 2 − and O − are the possible active oxygen species.