Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Diformylfuran over SBA-15 Supported Ruthenium Catalysts

In this study, the mesporous SBA-15 was prepared and used to graft biimidazole groups, which were used to anchor Ru3+ to give rise to a new ruthenium catalyst (SBA-15-Biimidazole-Ru). The structure of the SBA-15-Biimidazole-Ru catalyst was well characterized and used for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF). Several important parameters were studied and found that the reaction solvent and oxygen pressure showed a crucial role in the activity of the as-prepared SBA-15-Biimidazole-Ru catalyst. HMF conversion of 96.9% and DFF yield of 88.7% were achieved after 11 h at 110 degrees C under 15 bar oxygen pressure. One important characteristic of the SBA-15-Biimidazole-Ru catalyst is that it was very stable without loss of its catalytic activity during the recycling experiments, which was due to the strong interaction between the Ru3+ and the Biimidazole groups on the surface of SBA-15. Finally, the direct conversion of fructose into DFF was also performed by the use of Amberlyst 15 and SBA-15-Biimidazole-Ru as two binary catalysts. The dehydration of fructose over Amberlyst 15 catalyst and the subsequent oxidation of HMF over SBA-15-Biimidazole-Ru catalyst afforded DFF with an overall yield of 72.4%.