Effect of fatty acid methyl ester on the mass transfer and rate of an acid transesterification reaction

In order to investigate the cause of a slow acid transesterification, effects of physical properties on mass transfer and reaction mechanism were studied in this work. Refined palm oil and methanol were reactants with sulfuric acid as a catalyst. Fatty acid methyl ester product acting as co-solvent was one of the studied parameters affecting physical properties of the solution mixture. Visualizations on a digital microscope were used to observe behavior of glycerol and ester. It was found that increasing the ester decreased viscosity and density, which enhanced solubility of the reactants and, consequently, increased reaction rate. Finally, the visualizations show that the reaction was two-phase liquid–liquid reaction, in which the methanol–sulfuric acid covered the oil rich droplet. Increasing ester improved mass transfer by reducing droplet size.