Gas-phase Dehydration of Glycerol over Supported Silicotungstic Acids Catalysts

Abstract

The gas-phase dehydration of glycerol to acrolein was carried out over 10 wt % HSiW catalysts supported on different supports, viz gamma-Al2O3, SiO2-Al2O3, TiO2, ZrO2, SiO2, AC, CeO2 and MgO The same reaction was also conducted over each support without HSiW for comparison Several characterization techniques, N-2-physisorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), the temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed oxidation (TPO) with mass spectroscopy and CHNS analysis were employed to characterize the catalysts The glycerol conversion generally increased with increasing amount of acid sites Ceria showed the highest 1-hydroxyacetone selectivity at 315 degrees C among the various metal oxides The supported HSiW catalyst showed superior catalytic activity to that of the corresponding support Among the supported HSiW catalysts, HSiW/ZrO2 and HSiW/SiO2-Al2O3 showed the highest acrolein selectivity In the case of HSiW/ZrO2, the initial catalytic activity was recovered after the removal of the accumulated carbon species at 550 degrees C in the presence of oxygen