Free fatty acid esterification using acidic heterogeneous catalyst in continuous packed bed reactor

Abstract

Bentonite clay was treated with 0.5 M H2SO4 by ion-exchange method. The treated bentonite was characterized by x-ray fluorescence spectroscopy (XRF), x-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), N2 adsorption-desorption and thermogravimetric analysis (TGA). Esterification of 15 wt% oleic acid in refined palm oil with alcohol was treated over bentonite as catalyst in a continuous packed bed reactor. The various reaction conditions such as mole ratio of oleic acid to alcohol, amount of initial free fatty acid, catalyst height and reaction temperature were studied. The optimum condition of oleic acid was performed under mole ratio of alcohol to oleic acid as 54, catalytic height 25 cm (13.5 g) at 60°C in one column experiment. The highest FFA conversion was obtained at 92.6% and 94.9% for methanol and ethanol, respectively. Meanwhile, the highest FFA conversions were 78.3% and 86.6% for Jatropha curcas oil esterification with methanol and ethanol, respectively. When ethanol was used, FFA conversion was higher than methanol due to increasing solubility between oil and alcohol. The catalytic activity of reused catalyst was decreased due to acid leaching and decomposition of montmorillonite structure.