Catalytic Conversion of Glucose into Levulinic Acid Using 2-Phenyl-2-Imidazoline Based Ionic Liquid Catalyst

Levulinic acid (LA) is an industrially important product that can be catalytically valorized into important value-added chemicals. In this study, hydrothermal conversion of glucose into levulinic acid was attempted using Bronsted acidic ionic liquid catalyst synthesized using 2-phenyl-2-imidazoline, and 2-phenyl-2-imidazoline-based ionic liquid catalyst used in this study was synthesized in the laboratory using different anions (NO3, H2PO4, and Cl) and characterized using H-1 NMR, TGA, and FT-IR spectroscopic techniques. The activity trend of the Bronsted acidic ionic liquid catalysts synthesized in the laboratory was found in the following order: [C(4)SO(3)HPhim][Cl] > [C(4)SO(3)HPhim][NO3] > [C(4)SO(3)HPhim][H2PO4]. A maximum 63% yield of the levulinic acid was obtained with 98% glucose conversion at 180 degrees C and 3 h reaction time using [C(4)SO(3)HPhim][Cl] ionic liquid catalyst. The effect of different reaction conditions such as reaction time, temperature, ionic liquid catalyst structures, catalyst amount, and solvents on the LA yield were investigated. Reusability of [C(4)SO(3)HPhim][Cl] catalyst up to four cycles was observed. This study demonstrates the potential of the 2-phenyl-2-imidazoline-based ionic liquid for the conversion of glucose into the important platform chemical levulinic acid.

Automated summary

This study successfully synthesized Brønsted acidic ionic liquid catalysts for the conversion of glucose into levulinic acid, with [C(4)SO(3)HPhim][Cl] catalyst showing the highest activity.