Hydration of ethene over W–P mixed metal oxide catalysts

Abstract

W–P mixed metal oxide catalysts are active and selective for the gas-phase hydration of ethene to ethanol. The activity and selectivity of this catalytic reaction depend on the W/P atomic ratio. However, ethene conversion slightly decreases at higher W/(W + P) atomic ratio. The selectivity for ethanol increases with the W/P atomic ratio and reaches the highest value (92%) at W0.81P0.19Ox. The W0.81P0.19Ox catalyst is less active than the conventional H3PO4/SiO2 catalyst, but the activity is maintained for a long time without the supply of any catalyst components. The reaction temperature does not affect substantially the rate of ethene hydration over the W0.81P0.19Ox catalyst. The H2O/ethene molar ratio of 0.4 is the most appropriate for both reaction rate and selectivity. The active species of W–P mixed metal oxide are amorphous. But there is Keggin structure of W–P oxide species (PW12O40 3−) in the presence of steam. And the species are the active sites for the hydration of ethene, confirmed by in situ Raman spectroscopy.