Combustion of lean methane over Co(3)O(4) catalysts prepared with different cobalt precursors

To investigate the effect of catalyst precursors on physicochemical properties and activity of lean methane catalytic combustion, a series of Co(3)O(4) catalysts were prepared via a precipitation method by using four different cobalt precursors: Co(C(2)H(3)O(2))(2), Co(NO(3))(2), CoCl(2), and CoSO(4). The catalysts were characterized by BET, XRD, SEM, Raman, XPS, XRF, O(2)-TPD and H(2)-TPR techniques. It was found that the different types of cobalt precursor had remarkable effects on the surface area, particle size, reducibility and catalytic performance. In contrast, the Co(3)O(4)-Ac catalyst showed a relatively small surface area, but its activity and stability were the highest. XPS, Raman, O(2)-TPD and H(2)-TPR results demonstrated that the superior catalytic performance of Co(3)O(4)-Ac was associated with its higher Co(2+) concentration, more surface active oxygen species and better reducibility. In addition, the activity of the Co(3)O(4)-S catalyst reduced significantly due to the residual impurity SO(4)(2−), which could reduce the concentration of surface adsorbed active oxygen species and inhibit oxygen migration.