Promising sequential valorization strategy for eucalyptus to produce dissolving pulp, furfural and lignin

Aiming towards fully valorizing biomass, this study proposed an integrated process for eucalyptus to produce dissolving pulp, furfural and reactive lignin by using spiral extrusion with sequential p-toluenesulfonic acid (p-TsOH) pretreatment. Under optimal conditions (70 wt% p-TsOH, 80 °C, 50 min), 80.0% and 79.5% of lignin and hemicellulose were removed, respectively, while 92.2% of cellulose was retained in solid residue. After further cooking and bleaching processes, the dissolving pulp with 96.1% of α-cellulose content was obtained. Moreover, 75.6% of furfural yield was reached from the hydrolysate without additional catalysts for 170 °C at 50 min. The dissolved lignin showed low β-O-4 content and molecular weight with high phenolic OH content, which was suitable for lignin-based materials. This study provides a sequential valorization strategy for eucalyptus to produce dissolving pulp, furfural and reactive lignin, which would achieve the separation and directed transformation of all components of eucalyptus wood.