Deconstruction of Lignocellulose Recalcitrance by Organosolv Fractionating Pretreatment for Enzymatic Hydrolysis

Lignocellulosic biomass is a potential feedstock to produce the second-generation cellulosic ethanol and high-value-added chemicals. In order to increase the enzymatic digestibility of lignocellulosic biomass for efficient bioconversion, various pretreatment approaches have been studied. Among them, organosolv pretreatment is promising owing to its ability to achieve a biomass fractionation in one-pot process with efficient enhancement of the enzymatic digestibility. In this chapter, the research progress in recent years regarding different types of organosolv fractionating pretreatment methods (e.g., alcohol-based, organic acid-based, ketone-based, etc.) has been discussed, in terms of process operation, mechanism for improving enzymatic digestibility, and the lignin reactions during pretreatment. Organosolv fractionating pretreatment not only improves the enzymatic efficiency of the biomass but also shows great potential to achieve a full utilization of the main components. However, most existing organosolv-based biorefineries are just in pilot or demonstration scale mainly due to the high operation cost and energy consumption. To improve the economic feasibility of the organosolv pretreatment, more products with high value added should also be developed in the future.