An Anderson-type polyoxometalate triggers aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) is an environmentally sustainable, economically feasible, but substantially challenging conversion owing to the high energy barrier of O 2 activation. Herein, we report a catalyst with Mo 5+ connected to the oxygen vacancies (Mo 5+ -□) in Anderson-type polyoxometalate (POM) [(C 18 H 37 ) 2 N(CH 3 ) 2 ] 6 Mo 7 O 24 for oxidizing HMF to DFF. The resultant catalyst with high Mo 5+ content presents superior HMF oxidation performance, delivering a > 99% DFF selectivity with complete HMF conversion. Mechanistic studies and density functional theory (DFT) calculations reveal that the Mo 5+ -□ species in the catalyst facilitate O 2 activation and HMF oxidation. Moreover, the catalyst exhibits outstanding catalytic stability during the aerobic oxidation of HMF to DFF.