Zirconium phosphate combined with Ru/C as a highly efficient catalyst for the direct transformation of cellulose to C6 alditols

Abstract

The selective transformation of cellulose to C₆ alditols provides a feasible route towards the sustainable synthesis of chemicals and fuels. Herein, the catalytic performance of amorphous zirconium phosphate (ZPA) combined with 5 wt% Ru/C was evaluated in the direct conversion of cellulose to C₆ alditols (sorbitol and mannitol) under hydrothermal conditions. The yield of C₆ alditols reached 63.5% and 85.5% with microcrystalline cellulose and ball-milled cellulose as the feedstock, respectively. This hybrid catalyst was developed to convert concentrated cellulose to obtain C₆ alditols with a high concentration of 68.8 mg mL⁻¹ in the final products. The high yield of C₆ alditols from cellulose was ascribed to the fact that ZPA favoured the adsorption of cellulose and promoted its depolymerization to cellobiose and glucose, which was hydrogenated immediately to C₆ alditols over Ru/C. The weak adsorption of C₆ alditols over ZPA inhibited the dehydration of C₆ alditols to sorbitan. Furthermore, ZPA exhibited excellent hydrothermal stability and could be reused for several runs.