Catalytic Conversion of Concentrated Glucose to Ethylene Glycol with Semicontinuous Reaction System

Catalytic conversion of biomass to bulk valuable chemicals is of great significance for humanity, alleviating the dependence on fossil energy resources. Herein, the catalytic conversion of concentrated glucose to ethylene glycol (EG) was studied with dual-functional catalysts in a semicontinuous reaction system. Among a variety of tungsten-based catalysts, AMT-Ru/AC gave the highest EG yield of 60.0% as the mole ratio of W to Ru active sites was in an optimal range of 5-8. Higher temperatures (over 200 degrees C) and lower concentration of reactant are beneficial to the EG production. The reaction kinetic study disclosed that the reaction selectivity dependent on temperature should be attributed to the big discrepancy in the activation energies between glycol aldehyde (GA, precursor of EG) and EG formation, while the selectivity sensitive to feedstock concentration should be primarily due to the GA side reactions which follow a higher order kinetics (pseudo second order) than the GA hydrogenation to EG (first order). The semicontinuous reaction system well controlled the reactants at low concentrations by a differential effect on the feedstock but realized the product concentration integral to the proceeding of the reaction. In this way, EG was effectively produced from concentrated glucose with high selectivity. Also, this reaction system was found to be suitable for the catalytic conversion of fructose to EG and propylene glycol. The present work provided a valuable strategy for the catalytic conversion of active biomass such as glucose and fructose to glycols, particularly for their practical applications on a large scale.