Selective dehydration of glycerol to acrolein over mesoporous WO3-KIT-6: effects of mesoporosity and acidity

Abstract

The catalytic performance of tungsten oxide, WO3-KIT-6 in the selective dehydration of glycerol to acrolein was studied. The chemical and structural properties of the catalysts were examined by X-ray diffraction (XRD), nitrogen adsorption-desorption (BET) isotherms, temperature-programmed ammonia (TPD-NH3) desorption, and X-ray photoelectron spectroscopy (XPS), SEM, TGA, Raman and pyridine adsorption FTIR. Catalysts synthesized by the hydrolytic sol-gel (HSG) method showed quantitative conversion of glycerol and acrolein selectivity. The medium-strength surface acidity of the catalyst and mesoporosity played a crucial role in the dehydration of glycerol to acrolein. The maximum stable acrolein selectivity of 55% at 98% glycerol conversion was obtained over 25 wt%W-KIT-6(100) (7.9 nm average pore size) catalyst having the highest concentration of medium-strength acid sites. The effects of mesopore sizes and the selective dehydration of glycerol were elucidated. The catalyst with the largest mesopores diameter displayed higher reactivity, longer lifetime, and improved selectivity.