Efficient Conversion of Levulinic Acid to Methyl Levulinate Over SO^2-₄/SnO₂ Nanocatalysts

The present work focus on the synthesis of x% SO^2-₄ loaded SnO₂ nanocatalyst at different percentages (x = 2.3, 4.6, 6.9, 9.2, and 11.5% w/w) for acid-catalyzed esterification. The synthesized catalysts were characterized by X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), brunauer-emmett-teller (BET), scanning electron microscopy (SEM), transmission electron microscope (TEM), temperature-programmed desorption, and thermal gravimetric analysis (TGA/DTA) techniques. Methyl levulinate is an important chemical feedstock and its production through a catalytic route has been explored in this work. All the synthesized catalysts show excellent catalytic activity towards liquid-phase esterification of levulinic acid (LA) in atmospheric pressure under non-corrosive and mild conditions. The various reaction parameters like the effect of sulfate content, reaction temperature, reaction time, molar ratio of reactants, and prepared catalyst weights are optimized to get the highest conversion and selectivity of methyl levulinates. Among them, as prepared 6.9% SO^2-₄ /SnO₂ catalyst exhibits the highest conversation of levulinic acid (98%) and more selectivity towards methyl levulinate (100%). The catalytic stability and recyclability of the most active nanocatalysts were performed up to five successive runs and proves less variation in the catalytic activity.