VOx molecular level grafted g-C3N4 for highly selective oxidation of methanol to dimethoxymethane

Abstract

A composite material VOx/g-C3N4 was prepared and its composition and structure was characterized by FT-IR, XRD, SEM, TEM and XPS. The results showed that VOx was grafted on g-C3N4 surface with molecularlevel dispersion via V or O atoms interacting with the characteristic groups on g-C3N4 surface. The highly dispersed VOx/g-C3N4 exhibited effectively catalytic activity and high selectivity for oxidation of methanol into methoxymethane (DMM), giving 44.9 mol/(molV·h) TOF and 95.2% selectivity of DMM. The dependence of catalytic activity on the surface properties and preparation procedure of the catalyst, reaction conditions and kinetics, and the stability of the catalyst were explored. Also, the in situ DRIFTS spectra of methanol adsorption on the VOx/g-C3N4 surface and effect of O2 on the adsorption, as well as the reaction mechanism were discussed.