PNNL

Abstract

The relatively poor solubility of lignin in most pretreatment solvents remains one of the biggest challegnes in lignin valorization to improve overall biorefinery economics. In this work, rapid room temperature solubilization of lignin at high solid loadings (>30 wt%) can be easily achieved in a single step using ethylene glycol (EG). The solubilized lignin can be rapidly and quantitively recovered with the addtion of ethanol. The computational and nuclear magnetic resonance (NMR) spectroscopic studies confirm that strong hydrogen bond interactions between EG and the free hydroxyl groups present in lignin contribute to the lignin dissolution. In addition, hydrogen peroxide mediated depolymerization of dissolved lignin at low temperature (80 oC) was tested and the effect of EG molecules on depolymerization of ligin was also theoritically studied. The findings of this work provide mechanistic insights of hydrogen bond interactions in high lignin solubilization and valorization.