Waste to value addition: Utilization of waste corn cob from corn plant derived novel green acidic catalyst for effective synthesis of esters

Sulfonation of waste corn cob biomass (CCB) prepared a multifunctional mesoporous acidic catalyst for ethyl oleate production. For determining the best catalyst synthesis conditions, CCBs were calcineted at different temperatures (150-300 degrees C), sulfonated with 1, 3-propanesulfonate at different temperatures (60-140 degrees C), and sulfonation times (0.5-4.5 h). The structural, porosity, morphology and surface properties of the samples were thoroughly examined by FT-IR spectroscopy, TG analysis, SEM, N2 adsorption-desorption isotherms, XPS spectroscopy, and CHNS analysis. As a result of varying reaction conditions in catalyst optimization, including 8 g of 1, 3-propanesulfonate, 3 g of activated carbon CCB250, at 120 degrees C, and 4 h of reaction time, 94.32% of the -SO3H was obtained, and the catalyst surface was highly academically active. According to sulfur analysis of the CCB250-SO3H catalyst, the 120 degrees C sulfonated activated CCB250 contained -SO3H groups, with a higher density of active sites of 9.426 mol/g. By sulfonation of 1, 3-propanesulfonate, the mesoporous CCB250-SO3H catalyst was obtained with an average pore diameter of 3.1-4.8 nm, a pore volume of 1.39-1.02 cm3/g. The mesoporous CCB250-SO3H catalyst was utilized in the catalytic activity test to esterification with oleic acid. It exhibited a conversion rate of 94.32% in the production of ethyl oleate. The optimal conditions for this reaction included a catalyst loading of 150 mg, a molar ratio of ethanol to oleic acid (12:1 mol/mol), a reaction temperature of 80 degrees C, and a reaction time of 2 h. Due to the stable attachment of the -SO3H functional group, the mesoporous CCB250-SO3H catalyst was successfully reused eight times for esterification cycles.