Depolymerization in Supercritical Water

With the increasing global energy demand and escalating environmental problems, developing efficient and clean waste conversion technologies has become a pressing issue. Supercritical water depolymerization (SCWD), one of the hydrothermal treatment technologies, has garnered significant attention due to its ability to efficiently convert solid waste into high-value products under relatively mild conditions. This chapter reviews the application of SCWD technology in processing biomass, municipal solid waste, low-rank coals, and mixed raw materials. It also evaluates the effect of various reaction parameters (e.g., such as temperature, residence time, catalysts, pressure, co-solvents, and reactor types) on depolymerization products. Different raw materials exhibit distinct reaction characteristics and product distributions in SCWD, and optimizing reaction parameters can significantly enhance conversion efficiency and product quality. As hydrothermal treatments encompass both SCWD and subcritical water depolymerization, the chapter also discusses related applications of subcritical water depolymerization technology. Additionally, the chapter summarizes the downstream processing of crude products generated by SCWD. Overall, SCWD technology holds promise as a key solution to achieve a clean and sustainable resource transformation system.