High pressure phase behavior for the binary mixture of valeronitrile, capronitrile and lauronitrile in supercritical carbon dioxide at temperatures from 313.2 to 393.2 K and pressures from 3.9 to 25.7 MPa

High pressure phase equilibria for the (carbon dioxide + valeronitrile), (carbon dioxide + capronitrile) and (carbon dioxide + lauronitrile) systems are measured in static apparatus at five temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2 K and pressures up to 25.7 MPa. The three carbon dioxide + nitrile systems have continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and nitriles. The solubility of valeronitrile, capronitrile and lauronitrile for the (carbon dioxide + nitriles) systems increases as the temperature increases at a fixed pressure. The (carbon dioxide + valeronitrile), (carbon dioxide + capronitrile) and (carbon dioxide + lauronitrile) systems exhibit type-I phase behavior. The experimental results for the (carbon dioxide + valeronitrile), (carbon dioxide + capronitrile) and (carbon dioxide + lauronitrile) systems are correlated with Peng–Robinson equation of state using a mixing rule including one and two adjustable parameters.

► Phase equilibria for the (C5H9N), (C6H11N) and (C12H23N) in CO2 were measured.
► Experimental data were correlated with Peng–Robinson equation of state.
► The (carbon dioxide + nitriles) systems exhibit type-I phase behavior.