Non-catalytic reaction experiments of D-glucose and D-xylose were carried out at various operating conditions in subcritical water to explore optimum conditions that these monosaccharides can exist stably in subcritical water, and also to know reaction mechanism of these monosaccharides at identical condition, especially at higher feed concentrations. Experiments were conducted at temperatures of 160-280°C, pressures of 10-25 MPa, and a residence time of about 60s with a continuous flow-type reactor. The effect of feed concentration on the stability of the monosaccharides was also investigated. As a result, D-glucose and D-xylose remained about 80% and 50% at 200°C and 240°C respectively. The decomposition products were mainly fructose via tautomerism of D-glucose, 5-HMF by dehydration of D-glucose and D-fructose and 2-furfural from D-xylose via dehydration. At 240°C, organic acids such as lactic acid, glycolic acid and formic acid were produced from both saccharides. The thermal stability of monosaccharides decreased with increased the feed concentration.
展开▼
