Characteristics of Hydrochars Derived from Glucose, Protein, and Cellulose by Hydrothermal Carbonization Treatment

Abstract

With hydrothermal carbonization (HTC) treatment, wet biomass can be rapidly converted into hydrochar product with high-carbon content and calorific value. The current study employed glucose, protein, and cellulose as raw materials to investigate the effects of reaction temperature and residence time on characteristics of hydrochars. Results showed that the optimal reaction temperatures for glucose, protein, and cellulose were 240 °C, 190 °C and 220 °C, respectively. The optimal residence times were 4 h, 3 h and 4 h respectively, under which carbon microspheres with smooth surface and uniform particle size tended to form. The increased temperature promoted decomposition of bio-oil in the hydrothermal system and improved the quality of carbon microspheres, but much higher temperature deformed the surface of the carbon microspheres. Appropriate residence time ensured full growth of carbon microspheres but excessive residence time made the formed carbon microspheres to crosslink with each other, causing roughness to the surface. In addition, comparison of the specific surface area showed that the cellulose carbon microspheres exhibited an absolute advantage.