High-pressure phase behavior and modeling of binary mixtures for alkyl acetate in supercritical carbon dioxide

Experimental data of high-pressure phase behavior were measured for binary CO2–methyl acetate, CO2–ethyl acetate, CO2–propyl acetate, CO2–butyl acetate, CO2–pentyl acetate and CO2–hexyl acetate systems at several temperatures (313.2–393.2 °C) and pressures up to 16.45 MPa. These CO2–methyl acetate, CO2–ethyl acetate, CO2–propyl acetate, CO2–butyl acetate, CO2–pentyl acetate and CO2–hexyl acetate mixtures exhibit type-I phase behavior. In this work, three phases were not observed at any temperature of the systems. The solubility of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate and hexyl acetate for the CO2–methyl acetate, CO2–ethyl acetate, CO2–propyl acetate, CO2–butyl acetate, CO2–pentyl acetate and CO2–hexyl acetate systems increase as the temperatures increase at constant pressure. In each system, the mixture-critical point shifts higher as the temperatures increase, and also the mixture-critical pressure does as molecular weight increases.The experimental results for CO2–alkyl acetate systems are modeled using the Peng–Robinson equation of state. A good fit of the calculated data is obtained with the Peng–Robinson equation of state.