Studies on Esterification Kinetics of Short Chain Alcohols with Fatty Acids to Produce Biodiesel Fuel

Abstract

The kinetics of the esterification of fatty acid with some short chain alcohols have been investigated at different temperatures: 50, 60, and 70°C. Monhydric alcohols used in this study include methyl, propyl, and butyl alcohols. Sulphuric acid was used as a catalyst at concentrations from 0.008 to 0.02 molar H⁺ while the alcohol/fatty acid mole ratio was 20:1. The effect of temperature, catalyst concentration, and alcohol chain length on the reaction rate constant during the reaction course was investigated. Also, the influence of temperature on the kinetic rate constants was determined by fitting the results to the Arrhenius equation. The results have shown that there was an obvious relation between the alcohol chain length and the value of its activation energy or frequency factor. However, butyl alcohol, which has the longest chain length, has the highest energy of activation as well as the highest frequency factor. Based on the determined kinetic parameters, Ea, and arrhenius factor, a, the reaction rate constants of the esterification reaction using other temperatures ranging from 90–120°C were predicted theoretically.