Synthesis of 5-hydroxymethylfurfural from glucose over carbon-based acid-base bifunctional catalyst

Carbon-based acid-base bifunctional catalyst was synthesized by the functionalization of activated carbon (AC) with 3-mercaptopropyl trimethoxysilane, 3-aminopropyl trimethoxysilane, and H2SO4 via sulfhydrylation, ammonifiation, and sulfonation successively. The as-prepared catalyst of NH2-AC-SO3H was characterized by infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and Brunauer-Emmet-Teller specific area analysis, and it was further used for producing fuel precursor 5-hydroxymethylfurfural (5-HMF) from glucose. The influences of the catalyst type, ratio of acid-base groups, catalyst amount, reaction temperature, and reaction time were investigated. It was found that NH2-AC-SO3H revealed excellent activity, and the yield of 5-HMF reached 71.8% under the optimized reaction conditions with a 1.3:1 mass ratio of NH2-AC-SO3H to glucose at 140 degrees C for 6 h in gamma-valerolactone. The reusability of NH2-AC-SO3H was also performed, and only slight decreases in the conversion of glucose and the yield of 5-HMF were observed, still giving 65.3% yield of 5-HMF after 4 runs.