Catalytic Performance of Acid Catalysts for Sorbitol Dehydration to Isosorbide

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.