Direct oxidative transformation of glycerol to acrylic acid over Nb-based complex metal oxide catalysts

•W–V–Nb–O complex metal oxides having a structure like that of orthorhombic Mo3VOx were synthesized by hydrothermal method.•The materials were an efficient catalyst for the gas-phase direct oxidative transformation of glycerol to acrylic acid.•The catalytic performance was further improved by the surface modification with phosphoric acid, achieving ca. 60% one path yield of acrylic acid.