The selective aerobic oxidation of 5-hydroxymethylfurfural to produce 2,5-diformylfuran using nitrogen-doped porous carbons as catalysts

The selective aerobic oxidation of 5-hydroxymehtylfurfural (HMF) to synthesize 2,5-diformylfuran (DFF) using nitrogen-doped porous carbons as catalysts was achieved. The N-doped carbon materials were prepared by pyrolysis of chitosan with K₂CO₃ as an activator at 600 to 900℃. The N-doped porous carbon activated at 700℃ showed the highest catalytic activity in the conversion from HMF to DFF without any co-catalyst, i.e., the 95.3% HMF conversion and 94.6% selectivity of DFF under optimum reaction conditions (120℃, 7.5 h and 2.0 MPa O₂). According to the XPS results graphitic nitrogen on the surface of the catalysts played a critical role in the activation of O₂ to form oxygen radicals that facilitated the oxidative dehydrogenation of HMF.