Corncob waste derived carbon with sulfonic acid group: An efficient heterogeneous catalyst for production of ethyl levulinate as biodiesel additives.

Alkyl levulinate is a biomass-based chemical compound used as a fuel additive. This research aims to produce ethyl levulinate from levulinic acid and ethanol using esterification with the assistance of a heterogeneous sulfonated carbon catalyst. The carbon sulfonate catalyst is obtained from corncob waste that has undergone carbonization at 300 °C and sulfonation using sulfuric acid at a temperature of 150 °C for 8 h. The catalyst is used for esterification with predetermined operating variables using Box-Behnken Design (BBD) on the response surface methodology (RSM). The result shows significant variables for ethyl levulinate esterification are catalyst loading and esterification time. The FTIR analysis indicates the presence of S=O bonds in the sulfonated carbon catalyst. The XRD and SEM analysis shows that the sulfonated carbon catalyst is in amorphous and mesoporous form. Catalyst reusability demonstrates that the corncob-derived carbon sulfonate catalyst can be used up to 3 times. The optimum condition for esterification is 9 h of reaction, 10 % catalyst loading, and a molar ratio of levulinic acid to ethanol of 1:10, which has 83.15 % conversion. These results present the optimum parameter conditions for an efficient heterogeneous catalyst from corncob for producing ethyl levulinate.