Unprecedented glucose production using auto-catalytic hydrothermal hydrolysis of lignocellulosic biomass with no catalyst addition

We propose a novel and simple glucose production method involving autocatalytic hydrothermal hydrolysis of biomass without catalyst additives. This method consists of air-oxidation at a relatively lower temperature than that of the conventional method and subsequent hydrothermal hydrolysis. Japanese cedar (indigestible softwood) was initially air–oxidized by heating at 180–200 °C for 3 h. This induced the decomposition of a small portion of cellulose in the cedar sample, although 93.4% of cellulose remained at 200 °C. The functional acidic groups (phenol, lactonic, and carboxy groups) specifically increased during the initial air–oxidation. Following this, the acidic groups autocatalytically accelerated hydrothermal cellulose hydrolysis, resulting in a maximum glucose yield of 139.6 mg/g raw material at a severity factor (R0) of 3.2 × 104. Keywords: Cellulose hydrolysis, Oxidation, Glucose production, Hot compressed water, Hydrothermal treatment