Effect of MnO2 morphology on its catalytic performance in lean methane combustion

MnO₂ with nanocubes and nanorods were synthesized by a hydrothermal process, and their structures and catalytic performances in methane combustion were investigated. The activity results show that methane conversion over nanocubic MnO₂ is more than 90% at 350 °C, which is much higher than that of MnO₂ nanorods. N₂ physisorption, XPS and H₂-TPR results demonstrate that the superior catalytic performance of nanocubic MnO₂ is associated with its higher BET surface area, smaller crystalline size, more surface oxygen vacancies and better low-temperature reducibility. In situ DRFIFTS results demonstrate that the carboxylates species are the main intermediate species in methane oxidation.