Summary: Reaction calorimetry is an efficient tool used to obtain kinetic, thermodynamic and safety data. A reaction calorimeter, RC1e‐HP350, developed in collaboration with Mettler‐Toledo GmbH, allows investigating chemical reactions under supercritical conditions. The main technical difference, compared with a classical liquid system, is that the whole reactor volume is occupied by the media. Heat transfer analysis in supercritical carbon dioxide (scCO2) by the Wilson plot method shows that the behavior of the internal heat transfer coefficient in scCO2 is the opposite of the one observed for classical liquid. In scCO2 the lower the temperature (above the critical point) the better the internal heat transfer coefficient. The evolution of scCO2 thermodynamical and transport properties near the critical point are responsible for this behavior. The dispersion polymerization of methyl methacrylate in scCO2, with the polydimethylsiloxane monomethacrylate as stabilizer, is used as a model reaction. A polymerization reaction enthalpy of ?56.9 ± 2.2 kJ · mol?1 is determined, being in good agreement with previously reported data. The results presented illustrate the accuracy of the heat balance model used and emphasize the potential of reaction calorimetry for the promotion of supercritical fluids technologies.
Technical comparison between liquid and supercritical reaction calorimetry.
