ZrO₂-doped Cu–Pd alloy catalyst for the direct synthesis of 2,5-dimethylfuran from cellulose in sub- and supercritical methanol

The direct conversion of cellulose to targeted chemicals remains challenging owing to its recalcitrant nature and highly oxygenated structure. Herein, we report a strategy to selectively produce 2,5-dimethylfuran (2,5-DMF) and 2,5-hexadione (2,5-HDN) directly from cellulose, with yields of 33.8% and 17.2%, respectively, over multifunctional heterogeneous ZrO₂-doped bimetallic Cu–Pd nanoparticles supported on the HY(5.1) catalyst (CuPdZr/Y) under supercritical methanol (scMeOH) conditions. Acidic and metallic sites on the catalyst are involved in sequential cascade reactions, including solvolysis, dehydration, hydrogenation (HD), and hydrogenolysis (HDO). The preferential adsorption of reaction intermediates on the oxygen vacant sites of ZrO_x located near the metallic sites promoted HD and HDO. H–D exchange reactions revealed that the hydroxyl hydrogens of methanol were the active hydrogen atoms participating in HD and HDO. The yields of 2,5-DMF and 2,5-HDN decreased marginally after the third run, indicating that CuPdZr/Y was highly robust under the scMeOH reaction conditions.