Mixtures of supercritical CO2 + (1‑octanol and/or n‑alkanes) at saturation: Density and viscosity measurements

Abstract

Density and dynamic viscosity data were measured at phase transition for binary mixtures of CO₂ with 1-octanol, n-dodecane and n-tetradecane, and ternary mixtures of CO₂ with (1-octanol+n-dodecane), (1-octanol+n-tetradecane) and (n-dodecane+n-tetradecane). Data were measured at conditions between 308 and 348 K and up to 28 MPa and modelled using commercially available models in Aspen Plus® V11. A variable-volume high-pressure cell equipped with a torsional quartz crystal viscometer was used to detect the phase transition visually and non-visually. Densities were measured using the cell’s calibrated volume. The non-visual phase transition pressures compared well with the visual measurements (%AAD_P <3 %). The density and viscosity data for the CO₂ +1-octanol exhibited an inversion, introducing a non-ideal, non-linear relationship between the physical properties and temperature. However, the addition of n-alkanes to the system removed these density and viscosity inversion effects. Further, the models poorly predicted the measured physical properties data, necessitating future improvements.