Selective double dehydration of sorbitol to isosorbide using sulfated SnO2 and sulfated SnO2/Hβ as heterogeneous catalyst

Abstract

Liquid phase dehydration of sorbitol in a solvent-free environment is carried out to examine catalytic activities of sulfated tin oxides (STO) and STO/Hβ catalysts. The catalysts were prepared by wet impregnation method and characterized by XRD, FTIR, TEM, N₂ physisorption, NH₃-TPD. Prepared catalysts were examined at different temperatures and various catalysts loading. Under optimized reaction conditions (temperature −220 °C, reaction time −3 h), both STO and STO/Hβ catalysts demonstrated complete conversion of sorbitol, achieving isosorbide selectivity of 66% and 87%, respectively. This may be due to higher surface area and high Bronsted acid sites of catalysts. Catalyst reusability was checked for 4 cycles and it was found that conversion remains intact and only minor change in selectivity of isosorbide was observed.