Ordered mesoporous MCo2O4 (M = Cu, Zn and Ni) spinel catalysts with high catalytic performance for methane combustion

Ordered mesoporous MCo₂O₄ (M = Cu, Zn and Ni) spinel catalysts were synthesized via nano-replication method using mesoporous silica KIT-6 as the hard template. They were applied to methane combustion, in comparison with bulk MCo₂O₄ spinel catalysts prepared by co-precipitation method. A combined N₂ adsorption-desorption, XRD and TEM results clearly confirm that mesoporous MCo₂O₄ (m-MCo₂O₄) spinel catalysts contain ordered mesostructure, resulting in the higher BET surface area and pore volume than bulk ones (b-MCo₂O₄). Moreover, the former catalysts demonstrate the better thermal stability as indicated by larger amount of MCo₂O₄ phase and smaller size of crystallite domain after calcination at 550 °C. Therefore, such excellent properties rationalize that the m-MCo₂O₄ spinel catalysts reveal higher catalytic activity for methane combustion than bulk counterparts. When it comes to the catalytic performance of the meso catalysts for methane combustion, the m-CuCo₂O₄ spinel catalyst has superior performance, which is related to the high normalized amount of Co³⁺ cations on the surface, as evidenced by XPS.