Density and viscosity measurements at phase transition in supercritical carbon dioxide + 1-dodecanol + 2-dodecanol mixtures

Abstract

The density and viscosity of binary CO2 + 1-dodecanol and CO2 + 2-dodecanol mixtures, and the ternary CO2 + (50 % 1-dodecanol+50 % 2-dodecanol) mixture were measured at phase transition. Phase transition was detected in a visual synthetic variable-volume view cell that had a torsional quartz crystal to measure viscosity. Density was calculated from the calibrated cell volume. Measurements are reported for 308 – 348 K and up to 28 MPa, and were modelled in Aspen Plus. Mutual solubility for the three mixtures decreases in the order CO2 + 2-dodecanol > > CO2 + (50 % 1-dodecanol+50 % 2-dodecanol) > > CO2 + 1-dodecanol. Phase transition pressures display temperature inversion in all three mixtures. At corresponding temperatures and pressures: 1) all mixtures have densities within 20 kg/m3 of each other; and 2) CO2 + 1-dodecanol mixture viscosities are the highest (maximum of ∼2 mPa.s), while ternary mixture viscosities (maximum of ∼1.2 mPa.s) are within 0.10 mPa.s of CO2 + 2-dodecanol mixture viscosities.