Conversion of glucose into 5-hydroxymethylfurfural catalyzed by chromium(III) Schiff base complexes and acidic ionic liquids immobilized on mesoporous silica

A series of novel catalysts were prepared by immobilizing chromium(III) Schiff base complexes and acidic ionic liquids onto the surface of MCM-41, and characterized by FT-IR, TG, XRD, SEM, TEM, NH3-TPD, ICP-OES and N2 sorption studies. The catalytic activity of the prepared solid catalysts was investigated for the conversion of biomass (mainly including glucose, fructose and inulin) in the presence of DMSO. The dependencies of catalytic activity on reaction parameters such as temperature, reaction time and solvent were investigated and the reaction conditions were optimized. A HMF yield of 43.5% was achieved from glucose using Cr(salen)-IM-HSO4-MCM-41 as the catalyst in DMSO at 140 °C for 4 h. Furthermore, the catalyst also demonstrated good activity, and as high as 83.5% HMF was directly obtained from fructose, and the HMF yield reached 80.2% when inulin was selected as the substrate. The immobilized catalysts developed in this study present improved performance over other solid catalysts, and they have been efficiently and easily recycled at least five times without significant loss of activity in glucose conversion and HMF yield.