Synthesis of palm oil-based trimethylolpropane ester as potential biolubricant: Chemical kinetics modeling

Abstract

The environmental impact of large amounts of lubricants from mineral oils has become an increasingly important issue. The use of rapidly biodegradable lubricants, vegetable products as well as modified vegetable oil esters, could significantly reduce the environmental pollution compared to mineral oils. A kinetic/mathematical model describing chemical transesterification of palm oil-based methyl esters (POMEs) with trimethylolpropane (TMP) to polyol esters has been developed. The kinetics of the transesterification reaction was modeled as three distinct elementary reversible series–parallel reaction mechanisms. The model considers the transesterification reaction to take place in both forward and reverse directions. The resulting kinetics equations were solved using ode45 solver function in MATLAB, where the rate constants of the proposed kinetic model were determined by minimization of errors based on the optimum criteria of statistical analysis and by comparing the component concentrations at maximum and at equilibrium. The forward and reverse rate constants of all three steps involved in the transesterification reaction were reported. The validity of the model was tested by comparing the observed experimental values with the theoretical calculated data. A good correlation between simulated results and experimental data was observed, confirming that the model was able to predict the rate constants with plausible accuracy. The new proposed kinetic model would facilitate the design of a pilot-scale chemical reactor for the transesterification of POME with TMP to obtain palm oil-based polyol esters as a potential biolubricant.