Phase equilibria of near critical CO2 + propane mixtures with fixed oils in the LV, LL and LLV region

Solvents like propane and carbon dioxide have been studied in previous works at supercritical and subcritical conditions and also as high-pressure liquid solvents for the extraction of lipids and oils. Propane is completely miscible with vegetable oils at room temperature but has liquid–liquid phase equilibrium with typical vegetable oils at temperatures between the lower critical end point (LCEP) and the upper critical end point (UCEP)—around 340 K and 370 K. In this temperature range, the propane solvent power for triglycerides is drastically reduced unless higher pressures are used to recover the single phase region.The use of propane + carbon dioxide mixtures can offer special properties regarding solvent power, selectivity and safety. In the present work experimental data on phase equilibria of sunflower oil + propane + carbon dioxide are measured in a windowed variable volume cell. The CO2 concentration effect on the emergence of the liquid–liquid equilibrium phenomena in ternary mixtures with propane and oil is studied.