Esterification Kinetics of Tributyl Citrate Production Using Homogeneous and Heterogeneous Catalysts

In this work, the production of tributyl citrate via catalytic and self-catalyzed esterification of citric acid with 1-butanol was studied. Both, methanesulfonic acid (MSA) and Amberlyst 70 ion-exchange resin were evaluated as catalysts in the reaction. The kinetic effects of the temperature-(353-393 K), the feed molar ratio of alcohol to acid (8:1 to 16:1), and Catalyst loadings (0.5-1.5 wt % of MSA, and the equivalent amount of Amberlyst 70) were evaluated. Experiments were carried out using stirred batch reactors under isothermal operation. A Box Box-Behnken design was used to optimize the number of experiments required to obtain a valid kinetic model. Chemical equilibrium conditions were evaluated independently from kinetic experiments, reducing the number of parameters to adjust during data regression. Self-catalytic rate of reaction was also evaluated, and it was included within the overall kinetic model. The obtained models show good agreement with experiments, and they can be used for process analysis and simulation.