Understanding the effect of reaction parameters on the production of levulinic acid from glucose

Abstract

A significant and sustainable feedstock for many value added products is levulinic acid, which is basically a short-chain fatty acid. The current study aims to comprehend how multiple factors affect the hydrothermal reactions that convert glucose to levulinic acid. Glucose can be readily obtained from lignocellulosic biomass and hence it is selected in the work as representative sustainable source. The effect of various operating parameters, including time (0–180 min), temperature (140–180°C), nitrogen pressure (0–25 bar), glucose concentration (3%–10%), agitation speed (100–300 RPM), and acid concentration (2%–6%); use of different salts (NaCl, AlCl₃ 6H₂O, FeCl₃); and different acids (HCl, H₃PO₄, H₂SO₄) on the reaction progress has been studied in a batch autoclave reactor. It was elucidated that pressure (only nitrogen purge was essential for reaction progress) or salt content changes did not affect sugar conversion significantly. The process was seriously influenced by the presence of acids, mostly in the form of homogeneous catalysts, and the most significant results were obtained for H₂SO₄. The highest levulinic acid yield (39.7 g/g) at 90 min, with nearly complete sugar conversion, was obtained under the ideal conditions of 160°C, 5% sugar loading, and 5% H₂SO₄ concentration. The current study indicates that the two primary operating parameters in this conversion process are temperature and time, with higher temperature and lower sugar concentration showing a rising tendency in sugar conversion. Overall, the study establishes a sustainable process for levulinic acid synthesis.