Decoupling Multiple Potentially Runaway Reactions using Calorimetry: Acid Catalyzed Esterifications Case Study

The application of reaction calorimetry to fast and exothermic processes is a cornerstone in process safety analysis, especially when potentially runaway phenomena can be triggered by uncontrolled temperature rise. Peltier-cell calorimeters allow for accurate measurement of heat flow signals during semi-batch or batch experiments. However, in systems involving multiple consecutive or parallel reactions, the measured overall heat flow is a convolution of different contributions, complicating the interpretation of calorimetric data. This work addresses the challenge of decoupling heat flow signals to determine the reaction enthalpies of individual consecutive steps and to extract basic kinetic information. The acid-catalysed esterification of propionic anhydride with isopropanol was investigated as a case study. The process involves three exothermic reactions of comparable magnitude, whose simultaneous occurrence can hinder quantitative analysis. A systematic calorimetric approach was developed, combining experimental runs under isothermal conditions at different temperatures, calibration tests, mixing enthalpy determination, and signal deconvolution. The results demonstrate that, despite limitations, it is feasible to derive reliable estimates of reaction enthalpies and to infer kinetic behaviour directly from Peltier calorimetry. The methodology is discussed in the context of process safety and productivity optimization, with emphasis on the importance of complementary techniques, such as NMR, to validate calorimetric findings.