Measured Densities and Viscosities of High-Pressure Carbon Dioxide–Isopropanol Mixtures

The density and viscosity of high-pressure, moderate-temperature carbon dioxide (CO2)–alcohol mixtures are important in various chemical processes, notably supercritical CO2 drying of aerogels. This study measured those of CO2–isopropanol (propan-2-ol) mixtures. Pressure was continuously varied from its value near the liquid–vapor phase boundary up to about 15 MPa at temperatures of 313.15 K, 323.15 and 333.15 K for discrete CO2 mass fractions between 0 and 1, substantially extending the database of thermophysical properties for this system. Density, which increases with CO2 mass fraction until a maximum and then decreases to that of pure CO2, was measured using 3 redundant methods, viz., a variable-volume cell with an expanded uncertainty (k = 2) of 2.0% of reading, a Coriolis meter with a vendor-specified accuracy of ±7 kg/m3, and, to verify selected data points, a “bomb” experiment with an expanded uncertainty (k = 2) of 1.0% of reading. Viscosity was measured with an oscillating-piston sensor with a vendor-specified accuracy of ±0.02 mPa·s, monotonically decreasing by about 2 orders of magnitude between a CO2 mass fractions of 0 and 1 when temperature and pressure are constant.