Origin of the high activity and stability of Co(3)O(4) 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.