Partial oxidation of methane to methanol over M_xO_y/ZSM-5 (Mn, Fe, Co, and Ni) hierarchical transition metal oxide catalysts

The selective oxidation of methane to methanol is a key challenge in catalysis. The catalytic activities of nickel, cobalt, iron, and manganese oxides supported by hierarchical ZSM-5 zeolites for the partial oxidation of methane to methanol were studied. Hierarchical ZSM-5 was synthesized using a double-template method, in which tetrapropylammonium hydroxide was used as an MF1 structure-directing agent and PDDA-M was used as a mesopore-directing agent. The synthesized hierarchical ZSM-5 was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy with energy dispersive spectroscopy. M_xO_y/ZSM-5 catalysts were prepared using a wet impregnation method and were also extensively characterized. The catalytic test was performed at 423 K in a batch reactor with a CH₄. to N₂ ratio of 0.5:2 and 0.5 g of M_xO_y/ZSM-5 catalyst for 2 h. The hierarchical Fe₂O₃/ZSM-5 catalyst showed the highest yield of methanol, whereas Mn₃O₄./ZSM-5 tended to produce formic acid.