High Pressure Vapor-Liquid Equilibria Of Two Binary Systems Containing Carbon Dioxide And Alkanes

High pressure phase equilibrium data of the systems containingCO₂ is very important for supercritical fluid extraction, especiallyvapor-liquid equilibrium data of CO₂ and alkane with lowermolecule weight. The high-pressure vapor-liquid phase data ofthree binary systems (CO₂⁺ octane, CO₂⁺ heptane, CO₂⁺ hexane)have been measured in a cylindrical autoclave. The mole fractionsof carbon dioxide, densities and mole volumes of the two phases (at313k, 333k, 353k, 373k and pressure from 1Mpa to 15.9Mpa)respectively were obtained. The results show that the content ofCO2 in liquid phases increases drastically with pressures at thegiven temperature, but the contents of the alkane in gas phaseincrease faintly. At critical point, vapor phase and liquid phasebecame one phase, the critical values were estimated.The high-pressure VLE data are also calculated with fourmethods for above three systems. The PR and PRSV EOS and twodifferent mixing rules are used. The results show that the differenceof EOS and mixing rules lead to different calculated results.Panagiotopoulos-Reid mixing rules are better than Van der Waals-1for carbon dioxide + alkane systems.