Direct Conversion of Glucose to 5-Hydroxymethylfurfural over H_3PW_12O_40/TEOS Heterogeneous Catalyst

5-Hydroxymethylfurfural (5-HMF) is a valuable bio-based intermediate designed from carbohydrate resources such as glucose (hexose) or fructose. In this work, direct conversion of glucose into 5-HMF was studied by analysing the activity of solid acid catalyst namely silica-supported phosphotungstic acid (H_3PW_12O_40/TEOS) as a heterogeneous catalyst. The reactions were conducted in a three-neck conical flask using dimethyl sulfoxide (DMSO) as reaction solvent under different reaction time (1, 3 and 5 hours) and temperature (100, 115 and 130°C). The effect of phosphotungstic acid loading was also studied in this literature (5, 12.5 and 20% H_3PW_12O_40). Thus, this paper aims to study the optimum reaction time, temperature and H_3PW_12O_40 loading to give the maximum yield of 5-HMF via direct catalytic dehydration process. The prepared catalyst 20% H_3PW_12O_40/TEOS shows promising results by displaying a yield of 5-HMF as high as 62% after 3 hours at 130°C reaction temperature in the presence of DMSO solvent. Since heteropoly acid is highly soluble in DMSO, thus H_3PW_12O_40 supported in TEOS (H_3PW_12O_40/TEOS) is a promising solid catalyst for the conversion of glucose into 5-HMF. The prepared catalyst can also be recovered and recycled easily without significant loss of performance.