Kinetic study of liquid phase esterification of lactic acid with n-amyl alcohol catalyzed by cation exchange resins: experimental and statistical modeling

The liquid phase esterification of lactic acid with n-amyl alcohol over an acidic cationic exchange resin such as Indion 180, Amberlyst-15 and Seralite WRC-50 was carried out on a laboratory scale. The activity and performance of Indion 180, Amberlyst-15, and Seralite WRC-50 were evaluated. Kinetic experiments were conducted in a batch reactor in the reaction temperature range from 333 to 363 K. The Eley-Rideal and Langmuir Hinshelwood model was used to correlate the kinetic data and the estimation of kinetic parameters. The UNIFAC group contribution method was applied to study the nonideality in the reaction. Theoretically, mass transfer limitations were calculated from the reaction kinetics data. The activation energy and enthalpy of esterification reaction were found to be 43.71 +/- 0.56 and 51.42 +/- 0.64 kJ/mol. The response surface methodology was employed for statistical model development and optimization in the temperature range from 333 to 363 K, initial molar ratio 1 to 4, and catalyst loading from 2 to 8%. The maximum optimized conversion (53.89%) of lactic acid was found at temperature 357 K, molar ratio of 2.82, and catalyst loading of 6.17%. The predicted conversion (53.89%) by quadratic response surface model was good agreement with the experimental conversion (54.68 +/- 1.13).