Highly Selective Biphasic System for the Cyclic Transformation of Glucose into 2,5-Bis(hydroxymethyl)furan via Tandem Catalysis

Direct production of biomass-derived 2,5-bis(hydroxymethyl)furan (BHMF) from raw hexoses, especially glucose, is extremely desirable but challenging owing to the multistep reactions composed of isomerization, dehydration, and hydrogenation as well as inevitable side reactions to form humins involved. In this context, we developed a highly selective, energy-saving, and environmentally friendly approach to producing BHMF through the cyclic conversion of glucose in a water/ethyl acetate (EtAc) biphasic medium, in which ZIF-67, H₂SO₄, and CoNC-600 are used for catalyzing isomerization, dehydration, and hydrogenation, respectively. Under the optimized conditions, ∼40% glucose was converted to form BHMF with a desired carbon balance greater than 92% in the single cycle, where the unconverted glucose solution can be reacted in the next cycle. After the reaction, EtAc can be easily recycled by vacuum distillation at a low temperature and simultaneously afford solid BHMF with a purity of ∼90%. Moreover, s-CoNC-600 prepared from the spent ZIF-67 was still highly active and stable for the hydrogenation of HMF into BHMF. This work proposed an integrated and promising strategy for improving the selectivity of BHMF using low-cost glucose as the substrate, showing a great referential value for the industrial utilization of lignocellulosic biomass resources.