In situ FTIR investigation of the solubility and swelling of model epoxides in supercritical CO2

The phase behavior of carbon dioxide/epoxide mixtures has been investigated using an efficient in situ FTIR method that allows us determining the evolution of the concentration of each component in the two phases (CO2-rich phase and epoxide-rich phase) as a function of temperature and pressure. The measurements have been performed for three different temperatures (40, 70 and 100 °C) for pressures ranging between 0.1 and 20 MPa. We have selected propylene oxide (PO), styrene oxide (SO) and cyclohexene oxide (CO) molecules that are widely used in the synthesis of cyclic carbonates. Thus, we have determined the solubility of these epoxides in supercritical CO2 as well as the CO2 sorption and the resulting swelling of the epoxide rich phase. From these concentration measurements, we could establish the pressure-composition phase diagram of these epoxide/CO2 binary mixtures.