A binary catalytic system of sulfonated metal–organic frameworks and deep eutectic solvents towards highly efficient synthesis of 5-hydroxymethylfurfural from fructose

The green synthesis of 5-hydroxymethylfurfural (HMF) from biomass feedstocks is a crucial step for the development of sustainable fuels, resins and plastics. Here, a novel binary catalytic system was developed with metal–organic frameworks (MOFs) and deep eutectic solvents (DESs), which synergically exhibited a superior fructose dehydration efficiency with a HMF yield of 98.5% within 40 min. The replacement from terephthalic acid to 2,5-furandicarboxylic acid as the organic ligand in MOFs catalysts altered the coordination microenvironment of metal nodes, resulting in remarkably enhanced fructose conversion rates. The formation of hierarchical porous structures and moderated Brønsted acid sites in sulfonated MOFs further promoted the HMF production. Notably, HMF could be readily separated from the MOFs-DESs system and the MOF catalyst maintained stable performance after six recycles. Theoretical calculations clarified a positive correlation between the hydrogen bond interaction (between fructose and DESs components) energy and reaction efficiency. This study provided a new strategy to couple hierarchical solid acid catalysts with functional solvents binary towards effective and sustainable upgrading of biomass-derived molecules.