Direct Synthesis of 2,5-Diformylfuran from Carbohydrates Using High-Silica MOR Zeolite-Supported Isolated Vanadium Species

Directly transforming carbohydrates into high value-added chemicals provides an economic and sustainable path for the utilization of the renewable biomass resource. Herein, we fabricated an efficient catalytic system for the straightforward conversion of various carbohydrates into 2,5-diformylfuran (DFF) by using vanadium oxide supported on high-silica mordenite (MOR) zeolites in the presence of hydrochloric acid. The synthesis of high-silica MOR zeolites was achieved in a template-free dense system featuring energy savings and environmental friendliness, delivering the SiO₂/Al₂O₃ ratio up to 80. The conversion of fructose into DFF reached a high yield of 96.0% in a one-pot and one-step reaction by oxidation with atmospheric O₂ (balloon), with facile recovery and good reusability of the catalyst. Good yields were also obtained in the direct synthesis of DFF from other carbohydrates including glucose, sucrose, inulin, raffinose, maltose, and starch. The high performance relied on the unique high-silica MOR skeleton, which (1) endowed the highly dispersed V species mainly in the form of isolated tetrahedrally coordinated [V₂O₈]^6- species as the active oxidative sites and (2) provided satisfactory acidity for the formation of intermediate 5-hydroxymethylfurfural (HMF) and sufficient resistance to corrosion under an acid environment for good stability.