Developing a Continuous Process for Isosorbide Production from Renewable Sources

Abstract

Increasing demand for isosorbide has led to the search for sustainable and efficient methods for its production from sorbitol, a biomass-derived platform molecule. However, sorbitol dehydration to isosorbide is currently performed with mineral acids, resulting in safety and toxicity issues. Although some progress has been made towards replacement of liquid acids with heterogeneous catalysts, continuous systems with good stability, selectivity and productivity remain scarce. Herein, sorbitol dehydration to isosorbide is efficiently performed in a continuous, liquid-phase plug flow reactor, utilising an acidic zeolite (H-β (38)) as solid catalyst. H-β (38) is shown to catalyse the reaction without loss of activity for 55 hours on stream, achieving an isosorbide productivity of 9670 gisosorbide/kgcatalyst. This value is 4 times greater than any other continuous process reported in literature to date, even though the reaction was terminated prior to any loss of activity being detected. Diagnostic kinetic studies reveal improved operational conditions, and characterisation of the post-reaction catalyst is provided.