Identification of the Kinetic Parameters and Autocatalytic Behavior in Esterification via Isoperibolic Reaction Calorimetry

In the fine chemical and pharmaceutical industries, the operation of highly exothermic reactions with the autocatalytic features may lead to safety issues. From the safety point of view, identification of the autocatalytic features and the corresponding kinetics for a given reaction are of significant importance. In this work the simultaneots kinetic and thermodynamic analysis of a case reaction of esterification between acetic anhydride and methanol is first carried out under isoperibolic conditions using a reaction calorimeter. Two kinetic models, that is, autocatalytic kinetic model and second order kinetic model, are used to fit the temperature profile. The results show that the calculated reaction enthalpy (Delta H, 67.88 kJ/mol) by the autocatalytic kinetic model is much closer to the experimental value (63.22 kJ/mol) than that by second order model (100.06 kJ/mol), indicating that the autocatalytic kinetic model is more appropriate to the reaction. With the case study, we also demonstrate that an insight into the reaction mechanism and the proper selection of the kinetic model to fit the experimental data is crucial otherwise the improper selection of kinetic model could lead to misleading kinetic or thermodynamic parameters and then result in an incorrect estimation of the risk level of a given reaction.