A Kinetic Study for the Noncatalytic Esterification of Palm Fatty Acid Distillate

Abstract

In this work, the reaction scheme for the esterification of palm fatty acid distillate performed under the noncatalytic and high-temperature condition (230-290 degrees C) was investigated with a rigorous mathematical modeling. The esterification reaction was assumed to be the pseudo-homogeneous second-order reversible reaction, and the mass transfer effectiveness factor () was introduced in the modeling framework to systematically and collectively consider both evaporation and reaction, which are simultaneously and competitively occurred in the liquid phase. The nonlinear programming problem was constructed with the objective function consisting of the errors between experimental data and the estimated values from the reaction model. The problem was solved by using the Nelder-Mead simplex algorithm to identify kinetic parameters, reaction rate constants, and mass transfer coefficients. The values of mass transfer coefficients were found to follow the Hertz-Knudsen relation and expressed as a function of reaction temperature. From the reaction rate constants obtained from the proposed kinetic models, the apparent activation energy was estimated to be 43.98 kJ/mol, which is lower than the value obtained from the reaction using heterogeneous catalysts. This low value indicates that reactants and products behave as an acid catalyst at relatively high operating temperature and constant pressure.