Metal phosphate catalyzed dehydration of sorbitol under hydrothermal conditions

The intention of this work is to develop a heterogeneously catalyzed, environmentally friendly and sustainable process for the production of isosorbide by dehydration of sorbitol. The presence of the heterogeneous catalyst BP in the batch reactor had a great influence on the reaction rate. Trivalent B-, Al-, Fe-, Ce- and La-phosphates catalysts (MeP), as well as quadrivalent Zr-phosphates (ZrP-1 and ZrP-2) were studied in liquid-phase using autoclave reactors under autogenous pressure at different temperatures between 150 and 250 degrees C for different reaction times between 0.5 and 24h. The catalytic activity depends on the acidity of the catalysts, as NH3-TPD technique revealed, on the surface area and the pore diameter determined by N-2 adsorption. Depending on the pH of the reaction medium, water molecules play a significant role in the reaction. A tremendous effect was observed when 100 wt.% sorbitol powder was used instead of aqueous 70 wt.% sorbitol solution as starting material. (C) 2015 Elsevier B.V. All rights reserved.