Effective conversion of corn stalk into ethyl levulinate and crude lignin catalyzed by ionic liquids

Abstract

The chemical transformation of lignocellulosic biomass into platform chemicals is one of the most efficient utilization methods for agricultural wastes. In this work, a one-pot strategy for the conversion of corn stalk to ethyl levulinate and further extraction of valorizable lignin catalyzed by ILs was proposed. With the optimized catalyst of [C3H6SO3Hmim]HSO4, corn stalk of 92.45% was transformed into ethyl levulinate with a favorable yield of 24.72% at 200 °C for 90 min. Furthermore, the lignin extraction was substantially influenced by co-solution system. A high lignin yield of 79.94% was achieved with ethanol content of 75% (v/v) in the ethanol-water system. The analysis on morphology, thermal stability and functional group showed that condensation of lignin occurred during the liquefaction process, the two-dimensional heteronuclear single quantum correlation (2D-HSQC) investigation demonstrated that the stable structure of lignin provides a favorable foundation for its valorization. Overall, this work proposed a feasible biorefinery strategy for effective conversion and utilization of lignocellulosic biomass.