Effect of Temperature on Tarry Material Production of Glucose in Supercritical Water Gasification

Abstract

Our group studied the effects of temperature on the tarry material production of glucose under both subcritical and supercritical water conditions. The glucose solution (1.5 wt%) was gasified in a tubular reactor at 25 MPa pressure. The reaction temperature ranged from 300 to 450 °C. Gas products, char particles, and liquid products were observed, and the product yields were determined as a function of temperature. Tarry material was only produced under the subcritical water condition (300 and 350 °C) and was drastically changed or suppressed under the supercritical condition. To explain this, we speculated that the difference in water properties from the subcritical to the supercritical region altered the reaction mechanism. We also determined the kinetic parameters of glucose decomposition pathways by assuming the first-order reaction. The rate constant of overall glucose decomposition conformed to the Arrhenius behavior. The individual rate constant of glucose decomposition in subcritical temperature increased as the temperature rose but decreased in the supercritical condition. Different reaction mechanisms took place under two distinctly different regimes.