Autocatalytic hydrothermal pretreatment for eucalyptus wood and model construction of lignin dissolution and enzymatic hydrolysis processes

The green deconstruction and high-efficiency value addition of lignocellulosic biomass continue to be research hotspots in biomass refining. In this study, the autocatalytic hydrothermal pretreatment (AHTP) process was applied to reduce the biological recalcitrance of Eucalyptus wood. A statistical model was developed via the Levenberg-Marquardt method in least squares to predict lignin dissolution during AHTP of Eucalyptus wood. It shows excellent prediction performance and goodness of fit (R² = 0.9817, F = 377.0577 > Fα), thereby facilitating the simulation calculations and online control of the dissolved substances in the hydrolysate. Furthermore, the study examined the alterations in the solid microstructure during the AHTP, as well as the generation rules of the primary dissolved components and inhibitors. The optimal reaction condition for the pretreatment was determined to be 165°C for 90 min. In this condition, hemicellulose degradation products were significantly enriched and dissolved in the prehydrolysate, with the hemicellulose solubilization efficiency reaching 49.95 %. Meanwhile, the effect of AHTP on the hydrolysis efficiency of xylanase was investigated. The saccharification efficiency of the raw material hydrolyzed by xylanase after pretreatment was enhanced up to 40.96 % compared with untreated wood chips. This result indicated that AHTP substantially enhances the bioaccessibility of ensuing enzymatic process by overcoming the anti-degradation barrier of lignocellulose. The model system constructed in this study has the capacity to elucidate the migration and transformation mechanism of key components, and moreover, to provide a new strategy for the targeted regulation of the lignocellulosic biorefinery process.