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 O ₂ ^? and O^? are the possible active oxygen species.