An aluminum-grafted SBA-15-catalyzed conversion of glucose to 5-hydroxymethylfurfural

Environmentally friendly processes for preparing catalysts and converting glucose into 5-hydroxymethylfurfural (HMF) were studied under water-based conditions. A series of aluminum-grafted SBA-15 mesoporous silica with Si/Al molar ratios of 1.5–20 was prepared by tuning aluminum precursors, solvents, and the pH values in grafting. Among them, the 3Al-S15-w-pH 8 catalyst with high acid capacity and mixed acid sites of Lewis and Brønsted acids was fabricated by adjusting the pH value of the water-soluble aluminum precursor to 8 in a water medium. Thus, it converted 87% of glucose at 160 °C for 5 h in the water medium with 33% HMF selectivity. Moreover, the used 3Al-S15-w-pH 8 catalyst was easily regenerated by calcination in air, which was further used for converting glucose to HMF without losing its performance. Our findings provide new ideas for environmentally friendly catalyst preparation and biomass conversion methods, which can be readily applied to catalysis and bio-refining processes.