Catalytic performance of acid catalysts for sorbitol dehydration to isosorbide

Abstract

This research studied dehydration of sorbitol in aqueous solution to isosorbide over heterogeneous catalysts (Amberlyst-15, Purolite CT269, and H-beta) and a homogeneous catalyst (sulfuric acid). The dehydration of sorbitol was carried out in a high-pressure reactor under a nitrogen gas atmosphere at a fixed initial pressure of 2 MPa. It was found that the Purolite CT269 catalyst gave the highest sorbitol conversion of 100% and an isosorbide selectivity of 42% after 6 h at 453 K. The results showed that an increase in the reaction temperature gave rise to sorbitol conversion. However, the solid - compound was formed during the reaction at high temperature by polymerization of the product. The high acidity could catalyze the dehydration process; however, strong acid such as sulfuric acid gave low selectivity to isosorbide. Thus, the acidity of the catalyst plays a vital role in catalytic performance for the sorbitol dehydration to isosorbide.