Optimizing lignin oxidative depolymerization in single-phase binary solvent systems

Abstract

Lignin, a major component of lignocellulosic biomass, represents a promising renewable resource for the production of aromatic chemicals. However, its recalcitrant structure and chemical complexity pose significant challenges for efficient catalytic valorization. The low monomer yields and frequent repolymerization in conventional oxidative depolymerization systems further limit practical applications. This study aims to enhance lignin depolymerization efficiency through the use of binary solvent systems. Two solvent systems—methanol/water and methanol/formic acid—were evaluated for their effects on product yield and selectivity. Under optimized conditions, the methanol/formic acid system afforded a significantly higher monomer yield (21.99 wt%) compared to methanol/water. In this system, water helped stabilize the thermal environment, while formic acid acted both as solvent and hydrogen donor, facilitating bond cleavage and improving selectivity. These results underscore the importance of solvent composition and reaction conditions in achieving efficient lignin valorization for high-value chemical production.