Direct Production of 2,5-Dimethylfuran with High Yield from Fructose over a Carbon-Based Solid Acid-Coated CuCo Bimetallic Catalyst

A carbon-based solid acid, which functionalized with p-toluenesulfonic acid (TsOH), an encapsulated non-noble CuCo multifunctional heterogeneous catalyst was for the first time developed and used to catalyze the one-pot direct conversion of fructose into 2,5-dimethylfuran (2,5-DMF) without purification of 5-hydroxymethylfurfural (5-HMF) from the reaction solutions. Fructose was first transformed into intermediate 5-HMF over the outer shell carbon-based solid acid sites via dehydration, and subsequently 5-HMF was further converted to produce 2,5-DMF over the non-noble metal active sites in the core. As high as 71.1 mol % yield of 2,5-DMF was achieved in tetrahydrofuran at 220 °C and 3 MPa H2 for 10 h, which is higher than the yield reported for the direct conversion of fructose to 2,5-DMF. Besides, the carbon-based solid acid-coated CuCo catalyst could be reused up to five times.