Kinetic study of free fatty acid in Palm Fatty Acid Distillate (PFAD) over sugarcane bagasse catalyst

Biodiesel production is made by using edible or vegetable oils; however, their high prices and use as food resource are great limiting factors to their application. During the refining of palm oil, a lower-value by-product known as palm fatty acid distillate (PFAD) is generated in the fatty acid stripping and deodorization stages. PFAD is potentially a valuable, low-cost feedstock for the production of biodiesel. In this work, the esterification reactions of free fatty acid (FFA) in PFAD over sugarcane bagasse catalysts were studied. The effects of catalyst concentration (1 to 10 wt%), reaction temperature (30 to 60°C), and molar ratio of oil/methanol (1:6 to 1:12) on the conversion of FFA was studied to optimize the conditions for maximum conversion of FFA in PFAD and to observe the appropriate kinetic model for the experimental data. A kinetic model was developed on the basis of the Eley-Rideal mechanism according to the experimental data. The esterification reaction occurred between methanol adsorbed on solid base active sites and FFA from the liquid phase. The surface reaction of FFA with adsorbed methanol was assumed to be rate-determining. The collision factor value and activation energy for P-H model were found to be 1217.7985 L/mol.min and 24.2950 kJ/mol, then for E-R model were 1492.6375 L/mol.min and 19.5391 kJ/mol for E-R model, respectively.