Combustion of lean methane over Co3O4 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 Co3O4 catalysts were prepared via a precipitation method by using four different cobalt precursors: Co(C2H3O2)(2), Co(NO3)(2), CoCl2, and CoSO4. 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 Co3O4-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 Co3O4-Ac was associated with its higher Co2+ concentration, more surface active oxygen species and better reducibility. In addition, the activity of the Co3O4-S catalyst reduced significantly due to the residual impurity SO42-, which could reduce the concentration of surface adsorbed active oxygen species and inhibit oxygen migration.