Vapor-phase dehydration of several 1,2-alkanediols, such as 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol and 1,2-pentanediol, to produce corresponding aldehydes was investigated over silica-supported WO3 catalyst, which was prepared by impregnation method and then calcined at 320 degrees C. Higher than 90% yield of aldehydes could be achieved over WO3/SiO2 catalyst at 250 degrees C with a feed of 20% aqueous 1,2-alkanediol solution. Both Bronsted and Lewis acid sites exist on WO3/SiO2 catalyst, while Bronsted acid sites are proposed to be the active species for the formation of aldehyde. High concentrations of H2O were effective for inhibiting the intermolecular reaction and improving the selectivity to aldehydes. The dehydration of different 1,2-alkanediols was compared under different reaction conditions. The reactivity of 1,2-ethanediol was low and the product distribution was several comparing with those of the other 1,2-alkanediols. Cyclic acetal, which was generated by the cyclodehydration of the produced aldehyde with another 1,2-alkanediol, was a main by-product, and the formation of acetal was affected by both the temperature and the carbon-chain length of the 1,2-alkanediols. (C) 2016 Elsevier B.V. All rights reserved.