Efficient and accurate fractionation of eucalyptus using glycolic acid-catalyzed hydrothermal treatment and alkali treatment comprehensive technology

The effective utilization of lignocellulosic biomass is the key to evaluating the profitability of the process, and precise fractionation is a prerequisite for effective utilization. In this study, a high yield of fermentable sugars and lignin rich in phenolic hydroxyl groups were successfully obtained from eucalyptus using glycolic acid-catalyzed hydrothermal and alkaline treatment. The results showed that 88.20% of xylan and 85.07% of lignin were separated, and 62.68% of lignin was extracted from the hydrolysate. The extracted lignin has a complete structure and is rich in guaiacyl and syringyl units, which is conducive to the subsequent high-value utilization of lignin. 85% of glucan was recovered, and the glucose conversion yield was 84.24% after enzymatic hydrolysis. The hydrolysate can be concentrated, impurity removed, and purified to produce biofuels or chemicals after the precipitation of lignin. In summary, the two-step process based on glycolic acid has great potential in converting eucalyptus into biomass energy and chemicals, and this process is a promising precision fractionation strategy.