Changes in lignin properties during liquid hot water pretreatment and its role on enzymatic hydrolysis

摘要

As ‘second generation biofuels’, large efforts have been dedicated to the ethanol production from lignocellulosic biomass as a virtually sustainable material. However, the lignocellulose-to-bioethanol conversion has shown the difficulties in the efficient enzymatic hydrolysis of cellulose due to its recalcitrant and complex structure. Pretreatment is a necessary step to break down and disrupt the rigid and complex structure of lignocelluloses for enhancing the cellulose accessibility to enzymes. During hydrothermal processing such as liquid hot water pretreatment, the autocatalytic mechanism is linked to changes in lignin structures as well as hemicellulose solubilization. After pretreatment, the highly heterogeneous lignin structure is formed with a decreased number of β-O-4 linkages and a higher degree of condensation.