Nanobelt-arrayed vanadium oxide hierarchical microspheres as catalysts for selective oxidation of 5-hydroxymethylfurfural toward 2,5-diformylfuran

Abstract

Nanobelt-arrayed vanadium oxide hierarchical microspheres were synthesized to catalyze selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran with the high conversion and selectivity of 93.7% and 95.4%, respectively. This prominent performance can be attributed to the major exposure of (010) facet with highest hydrogen adsorption capability of vanadyl group (VO) sites and the highly oriented morphology for reactant contact and residence time control. Density functional theory calculation of the hydrogen adsorption capabilities on different facets and different chemical environmental sites has been utilized to explain the influence of different facets and lattice oxygen sites on 5-hydroxymethylfurfural oxidation performance based on hydrogen adsorption and αH-C bond cleavage steps. Isotopic studies verified the reaction mechanism and kinetic studies derived the first order reaction rate equation dependent on the 5-hydroxymethylfurfural concentration. These results suggested the crucial roles of (0 1 0) facets and the VO sites in O-H and αH-C bonds cleavage of 5-hydroxymethylfurfural before the reduction product V-OH species further dehydrogenation by molecular oxygen.