Acid-catalyzed esterification of free fatty acids with ethanol: an assessment of acid oil pretreatment, kinetic modeling and simulation

Abstract

This work reports experimental data and kinetic modeling of the esterification of different free fatty acids (lauric, stearic, oleic, and also an industrial mixture of fatty acids) with ethanol catalyzed by sulfuric acid. In addition, the esterification of acid oil was also studied. The effects of temperature (40, 50, 60, 70 °C), amount of catalyst (0.330, 0.425 and 0.66 wt% of H2SO4 related to the mass of substrate, which includes ethanol and free fatty acid) and initial molar ratio of ethanol to fatty acid (1:1, 6:1, 9:1, 12:1) were evaluated. The kinetics was modeled using an elementary mechanism approach considering a homogeneous system. The model parameters were estimated by fitting the kinetic model to the experimental data of lauric acid esterification, and, therefore, the model was used to predict the esterification of different feedstocks. The predictions were in a good agreement with the experimental data obtained, which means that the parameters adjusted for lauric acid esterification can be used for simulations involving acid oils and different types of free fatty acids.