Preparation of furfural from xylose catalyzed by difunctional carbon-based solid acid

A bifunctional carbon-based solid acid catalyst was prepared by sulfonation of sulfuric acid to using gelatin and phytic acid (PA) as carbon sources and doping with FeCl₃·6H₂O and ZnCl₂, which was used to efficiently catalyze the preparation of furfural from xylose. The catalysts prepared at different carbonization temperatures were characterized by SEM, BET, FT-IR and STEM-EDS techniques, and the physicochemical properties of the catalysts were revealed. The effects of carbonization temperature of the catalyst, molar ratio of FeCl₃·6H₂O to ZnCl₂, reaction temperature, reaction time, volume ratio of γ-valerolactone (GVL) to H₂O and catalyst dosage on the conversion of xylose to furfural (FF) were investigated. The results showed that the catalytic activity of CNPS600-Fe₄-Zn₂ was higher when the carbonization temperature was 600 ℃. The xylose conversion rate was 99.6%, and the molar yield of FF reached 85.8% when the reaction was carried out at 170 ℃ for 120 min using 0.03 g CNPS600-Fe₄-Zn₂ (the molar ratio of FeCl₃·6H₂O to ZnCl₂ was 4∶2) as catalyst, 3 mL GVL/H₂O (the volume ratio of was 9∶1) as solvent and 0.06 g xylose as raw material. In addition, the cyclic performance of the catalyst was tested. The FF molar yield and xylose conversion rate remained above 80% after 5 cycles, indicating that the catalyst had higher catalytic activity and better hydrothermal stability.