Phase equilibrium of the CO2/glycerol system: Experimental data by in situ FT-IR spectroscopy and thermodynamic modeling

Phase equilibrium experimental data for the CO2/glycerol system are reported in this paper. The measurements were performed using an in situ FT-IR method for temperatures ranging from 40 °C to 200 °C and pressures up to 35.0 MPa, allowing determination of the mutual solubility of both compounds. Concerning the CO2 rich phase, it was observed that the glycerol solubility in CO2 was extremely low (in the range of 10−5 in mole fraction) in the pressure and temperature domains investigated here. Conversely, the glycerol rich phase dissolved CO2 at mole fractions up to 0.13. Negligible swelling of the glycerol rich phase has been observed. Modeling of the phase equilibrium has been performed using the Peng–Robinson equation of state (PR EoS) with classical van der Waals one fluid and EoS/GE based mixing rules (PSRK and MHV2). Satisfactory agreement was observed between modeling results and experimental measurements when PSRK mixing rules are used in combination with UNIQUAC model, although UNIFAC predictive approach gives unsatisfactory representation of experimental behavior.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Glycerol–CO2 phase equilibrium experimental and modeling by in situ FT-IR and PR EoS. ► Data have been obtained at temperatures from 40 to 200 °C and pressures up to 35 MPa. ► Suitability of PR EoS with PSRK mixing rule and UNIQUAC model has been highlighted. ► Glycerol–CO2 system remains biphasic for all studied pressures and temperatures. ► Negligible swelling of glycerol by CO2 has been observed.