Catalytical conversion of fructose and glucose into 5-hydroxymethylfurfural in hot compressed water by microwave heating

Production of 5-hydroxymethylfurfural (5-HMF) from glucose and fructose catalyzed by TiO2 and ZrO2 under microwave irradiation was studied. For the case of TiO2 used in the fructose reaction, 5-HMF yield was 38.1% for a fructose conversion of 83.6% for 5 min reaction time. A 5-HMF yield of 30.5% for a fructose conversion of 65% was obtained for 5 min reaction time in the presence of ZrO2. The ZrO2 was found to promote isomerization of glucose to fructose, in which the selectivity of fructose from glucose became higher than 60% for about 50% glucose conversion for a reaction time of 1 min. Under the conditions (5 ml of 2 wt% fructose solution, 0.05 g of TiO2, 200 degrees C, and 3 min), fructose conversion and HMF yields by microwave heating (73% and 35%, respectively) were higher than those by sand bath heating (27% and 12%, respectively). (C) 2008 Elsevier B.V. All rights reserved.