Levulinic acid production from wood with green solvents

In this work, protic ionic liquid, 1-methylimidazolium hydrogen sulfate (HMIMHSO₄) and gamma-valerolactone (GVL) were explored with respect to their effects on levulinic acid production directly from cotton stalks and pine using the acidic catalyst, CrCl₃.6H₂O in a hydrothermal reactor. GVL as a biomass-derived solvent resulted in higher yields of levulinic acid compared to HMIMHSO₄ which was attributed to the higher lignin depolymerization capacity of the solvent and GVL’s capability for stabilization of the solvated protons. The increasing water content of the media from 10% to 20% enhanced the production and the yields. GVL gave the maximum levulinic acid concentration and yield from pine; 21.4 g/L and 78%, respectively when the reaction was conducted at 180 °C and 10% biomass loading with 20% water and 0.1 M CrCl₃.6H₂O for 4 h.