Catalytic synthesis and physiochemical characterization of ethyl levulinate from levulinic acid using amberlyst-15 as heterogeneous acid catalyst

The increasing global interest in sustainable energy systems and green chemical production has driven extensive research into the conversion of biomass-derived platform chemicals into high-value products. In this work, levulinic acid (LA) was initially synthesized from lignocellulosic biomass through acid-catalyzed hydrothermal processing using dilute hydrochloric acid under carefully controlled temperature and pressure conditions. The resulting levulinic acid was then upgraded to ethyl levulinate (EL) via esterification with ethanol, employing Amberlyst-15 as a reusable heterogeneous acid catalyst. The esterification process was conducted under optimized reflux conditions, with key operational parameters such as catalyst loading, reaction temperature, alcohol-to-acid ratio, and reaction time systematically considered to improve reaction efficiency and maximize product yield. The produced levulinic acid and ethyl levulinate were subjected to physicochemical and spectroscopic analyses to verify product identity and assess purity. Melting point analysis confirmed the quality of the synthesized levulinic acid, while Fourier Transform Infrared Spectroscopy (FT-IR) validated the transformation of functional groups during esterification, particularly the disappearance of the carboxylic O–H stretch and the emergence of ester-specific C=O and C–O vibrations. Further structural confirmation was obtained through Gas Chromatography–Mass Spectrometry (GC–MS), which displayed a molecular ion peak corresponding to ethyl levulinate alongside a dominant base peak characteristic of its fragmentation pattern. The high relative purity of the product indicates the effectiveness of Amberlyst-15 in catalyzing the esterification reaction under the applied conditions. Overall, the study presents an efficient and sustainable catalytic route for the production of ethyl levulinate from biomass-derived levulinic acid. The results underscore the suitability of Amberlyst-15 as a green heterogeneous catalyst for biomass valorization and highlight its potential application in the development of renewable biofuel additives and oxygenated industrial chemicals.