Abstract for presentation at Chemeca 2007

Biomass extracts, particularly sugars and other useful derivatives, from biomass hydrolysis are important products for further conversion to the production of biofuels. This paper reviews the current status and up-to-date progress of various biomass hydrolysis technologies, including acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis and hydrolysis using hot-compressed water. Advantages, disadvantages, typical operation conditions, products properties and applicability of these hydrolysis technologies are summarised and compared.

Enzymatic and acid hydrolysis processes are the main technologies being used for biomass conversion. There are still drawbacks of both technologies in treating lignocellulosic biomass. While the high crystalline structure of cellulose present in lignocelluloses inhibits access of the cellulase enzymes to the cellulose, acid hydrolysis requires corrosion-resistant materials and acid recovery recycle. Recently, hot-compressed water (super- and sub-critical) has been studied for the hydrolysis of cellulose and other highly polymeric materials. Water can be utilised as both solvent and reactant simultaneously. It can potentially be alternatives to corrosive acids and toxic solvents. This review summarises the decomposition mechanisms and hydrolysis products of model components of biomass, including cellulose and hemicellulose, as well as various biomass materials, under various conditions of hot compressed water. Key factors determining biomass hydrolysis in hot-compressed water are concluded. Future research for improving the sugar recovery is discussed.