Efficient and Subsequent Production of 2,5-dimethylfuran (DMF) from Fructose and 5-Hydroxymethyl furfural (HMF) Using Acid-Functionalized Mesoporous Silica Nanocatalysts

Due to strong demand for green and economical alternatives to traditional fossil fuels, this study is focused on the production of 2,5-dimethylfuran (DMF) converted from fructose or 5-hydroxymethylfurfural (HMF). In many biomass-derived liquid fuels, 2,5-dimethylfuran (DMF) is the most attractive one because of its excellent properties such as high energy density, efficient distribution, easier storage, and higher safety coefficient.
In this study, we synthesized several acid-functionalized mesoporous silica nanoparticles (MSNs) as solid heterogeneous catalysts because of several advantages of MSNs including high surface area and easy surface functionalization. Three acid-functionalized MSNs (i.e. sulfonic acid, carboxylic acid and phosphoric acid for S-MSN, C-MSN and P-MSN, respectively) were synthesized and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms and so on. It was found that S-MSN and C-MSN exhibited the highest efficiency for fructose-to-HMF and HMF-to-DMF, respectively, conversion in tetrahydrofuran (THF) system under mild conditions (75 °C, 15 hr). Therefore, we utilized these two catalysts to achieve efficient and subsequent fructose-to-HMF-to-DMF conversion with highest DMF yield of 69 mol%. The pathway of the HMF-to-DMF conversion was systematically studies. The acid-functionalized MSN materials synthesized in this study have shown potential applications as efficient catalysts for biomass conversion.