12-Tungstophosphoric acid/boric acid as synergetic catalysts for the conversion of glucose into 5-hydroxymethylfurfural in ionic liquid

An efficient process for the conversion of glucose into 5-hydroxymethylfurfural (HMF) with environmentally friendly and cheap catalysts was studied in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). Among the catalysts employed, the combination of 12-tungstophosphoric acid (12-TPA)/boric acid (B(OH)(3)) in the experiments resulted in the highest yield of HMF. The effects of various reaction parameters on HMF yields were also investigated. An HMF yield of 51.9% was achieved at 140 degrees C for 40 min. In addition, a small amount of water in this reaction system had little effect on the HMF yields. After the extraction of HMF, [BMIM]Cl and 12-TPA/B(OH)(3) could be reused and exhibited stable activities after five successive runs. More interestingly, like [BMIM]Cl, tetraethyl ammonium chloride (TEAC) could be favorable to HMF formation and was also used as an effective solvent for the conversion of glucose into HMF. (C) 2012 Elsevier Ltd. All rights reserved.