Vanadium oxide modified H-beta zeolite for the synthesis of polyoxymethylene dimethyl ethers from dimethyl ether direct oxidation

•VOx/H-beta catalysts were prepared at different calcination temperatures.•VOx offered suitable redox sites and tailored the acid properties effectively.•High B/L ratio was beneficial for the DMMx formation.•More strong acid sites promoted the C-O chain growth to synthesize DMM2-3.