One-Step Approach to 2,5-Diformylfuran from Fructose over Molybdenum Oxides Supported on Carbon Spheres

An effective one-pot process of synthesizing 2,5-diformylfuran (DFF) directly from fructose was accomplished over carbon sphere (CS)-supported molybdenum oxides (MoOx/CS) catalysts. The MoOx/CS catalyst was first prepared by a glucose hydrothermal carbonization method and subsequently annealed under different atmospheres. The annealing treatment under air at 275 °C afforded abundant mesopores over the CS and exposed more active sites. Kinetics studies suggested that 5-hydroxymethylfurfural (HMF) was the key intermediate; acid and oxide sites were active toward the dehydration of fructose and aerobic oxidation of HMF to DFF, respectively. A relatively faster dehydration rate compared to oxidation rate was critical for the dehydration of fructose to HMF instead of decomposing fructose under oxidative conditions. Under the optimized reaction conditions, nearly 78% yield of DFF at 100% conversion of fructose was obtained in dimethyl sulfoxide under atmospheric pressure of oxygen at 160 °C within 2 h.