Effects of the support on bifunctional one-step synthesis of methylal via methanol oxidation catalysed by Fe–Mo-based bifunctional catalysts

In the one-step preparation of methylal from methanol, achieving high methanol conversion and high methylal yield is a huge challenge. To address this problem, in this study a new Fe–Mo-based catalyst was designed, and the effect of the type and amount of the support on catalytic activity was explored. The results showed that Mo:Fe(2)/HZSM-5(80 + 80), in which HZSM-5(80 + 80) was the catalytic support, had excellent catalytic performance, with the yield of methylal reaching 81.33%, much higher than other reported results of this process. Through XPS, NH₃-TPD and PY-FTIR analyses it was found that the formation of Mo⁵⁺ promoted coordination of the two terminal oxygens with the Mo double bond in the Fe₂(MoO₄)₃ octahedron, and the higher the B/L acid site ratio, the better the catalytic activity and the higher the selectivity of the target product. The apparent activation energy also further proved that Mo:Fe(2)/HZSM-5(80 + 80) was highly suitable for the one-step production of methylal from methanol.