Hydrothermal liquefaction for producing liquid fuels and chemicals from biomass-derived platform compounds: a review

Biomass offers a promising alternative for producing biofuels and chemicals through hydrothermal liquefaction, a process known for its ability to convert complex organic materials into valuable liquid products. Optimizing hydrothermal liquefaction for large-scale application involves understanding the underlying mechanisms and addressing key scientific and technical issues. We review hydrothermal liquefaction of biomass-derived chemicals, focusing on the breakdown and depolymerization of cellulose, hemicellulose, lignin, lipids, and proteins under hydrothermal conditions. We examine critical parameters such as reaction temperature, pressure, solvent selection, and catalyst choice, and their impact on product yield and quality. Catalytic routes transform key intermediates, such as 5-hydroxymethylfurfural and levulinic acid, into high-value liquid fuels and chemicals, offering significant potential for sustainable fuel production. Recent advances in process optimization are discussed.