Efficient production of isosorbide from sorbitol dehydration over mesoporous carbon-based acid catalyst

Isosorbide, a renewable platform molecule from biomass-derived sorbitol cyclodehydration has attracted much attention over the years. The high yield production of isosorbide from sorbitol by an efficient heterogeneous catalyst under mild conditions is still a tough challenge. Herein, a mesoporous carbon-based acid MC-PhSO3H was prepared without assistant of additional templates via grafting benzenesulfonic acid groups to carbonized calcium citrate, and used as a recyclable catalyst to catalyze the dehydration of sorbitol to isosorbide under the solvent-free condition. The MC-PhSO3H exhibited highly efficient catalytic ability in isosorbide production with the yield of 82.7% at relatively mild reaction temperature of 160 degrees C within 1.5 h, which was superior to that of homogeneous H2SO4 and typical strong solid acid SO42-/ZrO2. The various characterization techniques such as N-2 adsorption-desorption, NH3-TPD, pyridine-infrared spectroscopy and sulfur elemental analysis revealed that the good catalytic performance of MC-PhSO3H was determined by its mesoporous structure with large surface area and pore volume, suitable hydrophilicity/hydrophobicity character, as well as high density of strong Bronsted acid sites. More importantly, MC-PhSO3H could be readily recovered and reused for five consecutive cycles.