Conversion of C5 Carbohydrates into Furfural Catalyzed by SO₃H‑Functionalized Ionic Liquid in Renewable γ‑Valerolactone

To obtain an efficient and green reaction system for the production of furfural (FF), this study investigated the use of a SO₃H-functionalized ionic liquid as a catalyst for the conversion of xylose in a solvent of renewable γ-valerolactone (GVL). A high FF yield of 78.12% was obtained in this reaction system catalyzed by 1-propylsulfonic-3-methylimidazolium chloride at 140 °C. The GVL remarkably enhanced the reaction rate and increased the xylose conversion and FF yield because the solvent effect of GVL could improve the catalytic activity of the acidic protons and suppress the side reactions. In addition, the ionic liquids showed satisfactory catalytic performance in the conversion of xylose to FF due to functionalization by introducing a SO₃H group. The conversion of other C5 carbohydrates (arabinose and xylan) was also tested in this system, and moderate FF yields were achieved.