Heteropolyacid-Assisted Efficient One-Pot Synthesis of Ethyl Levulinate from Biorenewable Feedstocks

Amid rising environmental concerns over fossil fuel dependence, biomass-derived alkyl levulinates, particularly ethyl levulinate (EL), have gained prominence due to their versatility in applications ranging from biofuels to lubricants and green solvents. This study presents an efficient, one-pot catalytic conversion of various carbohydrates (glucose, fructose, and sucrose) into EL using a tailored Keggin-type heteropolyacid catalyst with a vanadium-to-tungsten atom ratio of 1:11. Vanadium substitution imparts higher acidity and redox properties to the catalyst, which is reflected in the catalytic performance. The catalyst demonstrated outstanding performance, achieving high EL yields of 98 ± 1% from sucrose, 93 ± 2% from fructose, and 82 ± 2% from glucose under batch processing conditions (180 °C, absolute ethanol solvent, 27 wt % catalyst, 2 h). The high yield of EL may be assigned to the presence of both Brønsted and Lewis acid sites, which promotes key reactions like isomerization and ethanolysis. Moreover, a significant EL yield of 85 ± 2% was obtained from cellulose feedstock, which showcases the efficiency of this catalyst. The use of absolute ethanol as solvent enhanced esterification prospects, preventing hydrolysis and promoting higher EL yields, while the presence of water as cosolvent favored the formation of levulinic acid. These findings demonstrate the potential of vanadium-substituted heteropolyacid catalysts for efficient biomass valorization, offering a sustainable pathway for the large-scale production of EL from renewable feedstocks.