Some recent advances in hydrolysis of biomass in hot-compressed, water and its comparisons with other hydrolysis methods

Biomass hydrolysis extracts, particularly sugars and other useful derivatives, are important products for further conversion to produce biofuels. The past 2 decades have witnessed significant research and development activities using hot-compressed water for the hydrolysis and conversion of cellulose, hemicellulose, and lignocellulosic biomass materials. This paper summarizes the decomposition mechanisms and hydrolysis products of these materials under various conditions in hot-compressed water. Key factors determining hydrolysis behavior in hot-compressed water are also discussed. Comparisons are made between hydrolysis in hot-compressed water and hydrolysis using other technologies, including acid hydrolysis, alkaline hydrolysis, and enzymatic hydrolysis. Advantages, disadvantages, typical operation conditions, products properties, and applicability are summarized. Key research issues on hydrolysis in hot-compressed water are identified, and future research prospects to further improve the technology are discussed.