Efficient production of 5-hydroxymethylfurfural from glucose over sulfonated carbon/γ-Al2O3 composite

Sulfonated carbon/γ-Al 2 O 3 composites (AlSC-x, x = 1, 2, 3) were successfully prepared by the three-step method of impregnation-carbonization-sulfonation. The introduction of sulfonated sucrose-based carbon onto nano-γ-Al 2 O 3 enhanced its Brønsted acidity and weakened the original Lewis acidity. The Brønsted/Lewis acidity of the composite catalysts can be regulated by controlling the sulfonated carbon intake. AlSC-1 containing suitable Brønsted/Lewis acidity showed the best catalytic performance for converting glucose to 5-hydroxymethylfurfural (HMF). In monophasic DMSO/H 2 O (2.0/0.2 mL), an HMF yield of 62.3 % was achieved at 160 °C and 4.0 h when 0.02 g of glucose and 0.02 g of AlSC-1 were used. Adding a moderate amount of water into DMSO is crucial to improve HMF selectivity, and the DMSO/H 2 O system exhibited superior performance to other solvent systems, such as pure water, 1,4-dioxane/H 2 O, and GVL/H 2 O. More importantly, the recyclability of AlSC-1 was pretty good. In addition, AlSC-1 also exhibited much better performance than the other composite catalysts, including sulfonated carbon/nano-TiO 2 , sulfonated carbon/nano-ZrO 2 , and sulfonated carbon/nano-SnO 2 .