Transformation of wheat straw polysaccharides under dynamic conditions of subcritical autohydrolysis

摘要

Transformation of wheat straw polysaccharides under dynamic conditions of subcritical autohydrolysis has been examined at a pressure of 30 MPa in a temperature range of 150-290A degrees C. The dependence of the yield of gaseous, liquid, and solid products on the process temperature has been studied. The formation of liquid products occurs mainly due to the hydrolysis of pentosans and partially of cellulose in a range of 150-200A degrees C. The main components of liquid products are oligo- and monosaccharides. Xylose and arabinose comprise more than 65% of monosaccharides. A temperature rise in a range of 200-290A degrees C is accompanied by a decrease in medium pH, cellulose hydrolysis, and intensive gasification. Glucose predominates in monosaccharides of liquid products isolated at 270A degrees C; a portion of pentoses does not exceed 25% of the total of monosaccharides. The maximal yield of sugars is observed at 200A degrees C and then decreases from 29.6 to 5.3% per straw oven-dry weight at 270A degrees C. A decrease in reactivity of straw cellulose treated at 200A degrees C to enzymatic hydrolysis has been found.