One-Pot Reaction Conversion of Delignified Sorghum Bicolor Biomass into Levulinic Acid using a Manganese Metal Based Catalyst

Sorghum stems, an agricultural biomass waste, can be used as a raw-material carbon source for platform chemicals, such as levulinic acid. Levulinic acid can be produced with high percentage yields using delignified sorghum stems as starting materials. The purpose of this study was to evaluate manganese-based catalysts (Mn²⁺ and Mn₃O₄) as Fenton-like reagents for the production of levulinic acid from sorghum stems. A mixture of finely powdered delignified sorghum stems (containing 76.66% cellulose) dispersed in a mixture of phosphoric acid (40%), H₂O₂ (30%), and either 2% Mn²⁺ or 2% Mn₃O₄ as a catalyst in a one-pot mini reactor was observed at 130°C for 10 h. The yield of the conversion products was quantitatively analyzed for levulinic acid using high-performance liquid chromatography. The reaction using the Mn₃O₄ catalyst yielded a higher percentage of levulinic acid (26.57%) than the Mn²⁺ catalyst (25.59 %) reaction after 8 hours. This study points to the opportunity of the one-pot synthesis of levulinic acid using renewable biomass waste resources.