A two-phase reaction system for selective oxidative degradation of lignin model compounds

Abstract

Lignin depolymerization through an oxidation method could provide value-added products, but it is challenging in terms of recovering catalysts or separating products in time to avoid over-oxidation. In this study, a process of selectively oxidative degradation of lignin model compounds was operated in a two-phase reaction system. Lignin model compounds of 4-benzyloxyphenol (PBP) or guaiacylglycerol-β-guaiacyl ether (GGE) in a bottom phase of 1-butyl-3-methylimidazole chloride ([BMIM]Cl) ionic liquid were selectively oxidized by H2O2 in the presence of a solid acid (SO42-/Fe2O3-ZrO2), and the degradation products immediately diffused into the upper organic solvent phase (butyl acetate). In this kind of reaction system, the yield of the products was improved due to the prolonged life of [bullet operator]OH in ionic liquid, and the product selectivity was maintained due to the timely product separation, and the ionic liquid and the catalyst were easily recycled.