Glucose Decomposition in Water under Supercritical Pressure at 448-498 K

Abstract

The behavior of glucose under hydrothermal conditions is of great interest in the development of processes for supercritical water gasification and the hydrothermal pretreatment of lignocellulosics. Our group examined this behavior in a series of glucose decomposition experiments in water at a pressure of 25 MPa in the temperature range of 448-498 K. The rate parameters of the reactions from glucose to the decomposition products were determined by the least squares method. The reaction order of unity for glucose decomposition was found to be the result of several reactions of various reaction orders proceeding in parallel. The reaction orders for the decompositions of fructose, erythrose, glyceraldehyde, and 1,6-anhydroglucose can be considered unity without large error. By examining the selectivity of glucose conversion reactions, we determined that almost all of the glucose was initially converted into fructose, but at 498 K, 1,6-anhydroglucose and erythrose selectivity matched that of fructose. The kinetic parameters determined in our experiments should be useful for predicting the reaction taking place in the pre-heating section of the supercritical water gasification process and in the hydrothermal pretreatment reactor used for the saccharification of cellulosic materials.