Response Surface Optimization and Kinetics of Isopropyl Palmitate Synthesis using Homogeneous Acid Catalyst

Abstract

Abstract Fatty acid esters (FAE) are widely applied in the field of cosmetics, personal care products and various other allied applications. This work describes the synthesis of isopropyl palmitate (FAE) by esterification of palmitic acid with isopropyl alcohol catalyzed by p-toluene sulfonic acid (p-TSA) in a batch reactor. Response surface methodology (RSM) with Box-Behnken experimental design (BBD) was employed to design the experiments as well as to optimize the conversion of palmitic acid. The effects of various process parameters namely catalyst amount, molar ratio of alcohol to acid and reaction temperature on conversion of palmitic acid were evaluated. The high correlation coefficient (R2=0.973) between model and experimental data indicated that the data fitted well in the model. The optimal process conditions were found to be, catalyst amount of 5 % (wt/wt), molar ratio of alcohol to acid of 7:1 and temperature of 82 °C. Moreover, the kinetic model was developed at these optimized process conditions using second order kinetics and validated with experimental results. The kinetic model and experimental results were found to be in good agreement. The kinetic rate constants and equilibrium constant increased with increase in temperature. The activation energy and pre-exponential factor were found to be 45.21 kJ mol−1 and 1.96×105 L mol−1 h−1 respectively. The optimized process parameters obtained from RSM, equilibrium rate constants and the parameters evaluated from kinetic model may be useful for the simulation of pervaporation reactor and reactive distillation column for the synthesis of isopropyl palmitate.