Taguchi method for optimizing the cation exchange resin catalyzed esterification of oleic acid with ethanol and adsorption kinetics study

Abstract

In this study, solid acid catalysts (cation exchange resins) were used to catalyze the esterification reaction of acidified oil and ethanol for the preparation of biodiesel. The catalyst was characterized by SEM, BET, XRD, and FTIR. The esterification reaction was studied under various conditions using one-way analysis. Process optimization was performed by the Taguchi method, revealing that the optimal conditions for maximum oleic acid conversion (91.63%) were a catalyst dosage of 20 wt%, ethanol/oleic acid molar ratio of 9:1, reaction time of 5 h, and reaction temperature of 80 ℃. In addition, the adsorption behavior of cation exchange resin (S-CER) on oleic acid and ethanol during the esterification process was investigated. The Freundlich and Langmuir adsorption kinetic models of the resin were also established. This study focused on the dynamic equilibrium of oleic acid and ethanol adsorption on the S-CER catalyst surface. The adsorption process was found to align better with the Freundlich isotherm equation. According to this equation, oleic acid's maximum adsorption capacity was found to be 371.24 mg/g. Lastly, a pseudo-primary kinetic equation for the esterification reaction was formulated, and the calculated activation energy for the reaction was 35.59 kJ/mol.