A phase-transfer-assisted strategy for oxidation-based biomass valorization

Abstract

As the world's only carbon-containing renewable resource, lignocellulose utilization oriented toward high-value compounds under mild conditions is key to the sustainability of biorefineries. In this study, we report a typical phase-transfer catalyst, tetrabutylammonium bromide (TBAB), which facilitates the migration of substructures derived from solid lignocellulose into aqueous phases during the alkaline oxidative depolymerization process. The introduction of TBAB can convert lignin into vanillin with high selectivity under low pressure (4 bar) in a short time (40 minutes). The vanillin yield reached 32 wt% (on the basis of lignin weight), representing a 25% improvement over the optimal value previously reported. Simultaneously, the (hemi)cellulose fraction was converted into low-molecular-weight mixtures of aliphatic acids. The evolution mechanism of lignin was established through a comprehensive investigation of the lignin oil and lignin fragments produced during the depolymerization process. This work provides a promising strategy for the valorization of lignocellulose into value-added products and offers deep insights into the underlying depolymerization mechanisms.