Synthesis of Zeolitic Vanadotungstate with Trigonal Symmetry for Methane Oxidation to Methanol.

Zeolitic octahedral metal oxide is a potentially good catalyst due to its redox property and microporosity. The structure and chemical composition of a material affect its catalytic activity, therefore tuning these properties is very important. Herein, structure tuning of the zeolitic octahedral metal oxide based on vanadotungstate was studied in detail. The investigation into the formation of the material indicated that tungstate reacts with VOSO4 to form [W4O16]8- cubane units, K+ led to the formation of zeolitic vanadotungstate with cubic symmetry (VT-1), and trimethylamine led to the isomeric material with trigonal symmetry (VT-5). VT-5 was an effective catalyst for the selective oxidation of methane to methanol in water at a low temperature (90 °C), using only molecular oxygen as an oxidant. Methane was effectively converted to methanol with a high selectivity. The microporosity and reduced V site of the material were critical to achieving the high catalytic performance.