Kinetics for the Subcritical Treatment of Glucose Solution at Various Concentrations

Abstract

Kinetic analysis was performed for the isomerization of glucose and side reactions (decomposition) in subcritical water with low-to-high saccharide concentrations (0.001–0.40 kg/kg-water). An aqueous solution of glucose was treated under subcritical conditions at 200 °C for 30–400 s using a tubular reactor. Isomerization of glucose to fructose predominantly occurred when the glucose concentration was low, while isomerization to mannose scarcely occurred. Decomposition of glucose to byproducts was promoted with increasing glucose concentration, while the isomerization was suppressed. Selectivity of fructose and mannose for the isomerization became lower at higher glucose concentrations and with longer reaction times. Kinetic analysis of the reaction indicated that the decomposition step of fructose most greatly affected the selectivity of fructose during the subcritical water treatment of glucose.