Sustainable Production of Levulinic Acid from the Cellulosic Fraction of Pinus Pinaster Wood: Operation in Aqueous Media Under Microwave Irradiation

The fractionation of the structural components of lignocellulosic biomass (cellulose, hemicelluloses, and lignin) and the separate utilization of the resulting fractions for specific purposes, according to the philosophy of biorefineries, enables the development of sustainable processes for biomass utilization. In this work, Pinus pinaster wood was subjected to aqueous processing to remove water-soluble extractives and hemicelluloses, and the resulting solid was subjected to pulping with HCl-catalyzed acetic acid solutions (Acetosolv method). The pulp was employed as a substrate for levulinic acid manufacture by reaction in acidic media under microwave irradiation. The effects of the major operational variables (temperature, reaction time, and acid concentration) on the levulinic acid yield were established by statistical modeling of experimental data. Operating under the best reaction conditions (at 191.2°C for 18.9 min in aqueous media containing 1.10% HCl), the levulinic acid yield accounted for 56.4% of the stoichiometric value.