Hydrothermal Liquefaction of Biomass

Abstract Thermochemical methods are efficient routes for conversion of biomass. Among them, hydrothermal liquefaction is the most promising method as it can convert feedstocks (lignocellulosic biomass and algae) with very high moisture content into bio-oil and platform chemicals without energy-intensive pretreatment. In order to better understand the underlying reaction mechanisms and major experimental variables during hydrothermal liquefaction, this chapter describes the basic understanding of physical and chemical properties of subcritical water, hydrothermal liquefaction studies of individual biomass components as well as whole biomass, and their reaction paths and products. The role of process variables, including biomass composition, temperature, residence times, heating rate, particles size, solvent, catalyst, reactor configuration, and so on, that are important for the bio-oil yield and product quality is discussed in the chapter.