Insights into the Primary Decomposition Mechanism of Cellobiose under Hydrothermal Conditions

Abstract

This paper reports a systematic investigation on the primary decomposition mechanism and kinetics of cellobiose under hydrothermal conditions at 200–275 °C and a wide initial concentration range of 10–10,000 mg L–1. Isomerization of cellobiose to cellobiulose (glucosyl-fructose) and glucosyl-mannose dominates the primary reactions of cellobiose decomposition, contributing to 71–93% of cellobiose decomposition depending on reaction conditions. In contrast, cellobiose hydrolysis to glucose makes only limited contributions (6–27% depending on reaction conditions) to the primary decomposition of cellobiose. This indicates that hydroxyl ions have a more significant effect to catalyze the isomerization reactions to produce cellobiulose and glucosyl-mannose. The catalytic effect of hydronium ions is weak probably because of the high affinity of hydronium ions for water molecules, which reduces the availability of hydronium ions for catalyzing the hydrolysis reaction. At increased temperatures, the affinity of hy...