Vapor-liquid equilibria near critical point and critical points for the CO₂ + 1-butanol and CO₂ + 2-butanol systems at temperatures from 324 to 432 K

An apparatus based on the static-analytic method to perform fast determinations of VLE and critical pressures for mixtures up to 60 MPa and 523 K was used. VLE near critical points and critical points of the following mixtures: CO₂ + 1-butanol at 324.16, 333.58, 355.38, 392.72, and 426.95 K up to 17 MPa and CO₂ + 2-butanol at 335.14, 348.77, 374.10, 402.47, and 431.73 K up to 14.5 MPa were reported over the range of compositions near critical points. The results demonstrated the ability of the apparatus to achieve reliable, VLE near critical points and critical points of fluids mixtures determinations up to 431 K and 17 MPa. The VLE of the CO₂ + 1-butanol and CO₂ + 2-butanol systems were measured and were represented correctly with the Patel-Teja EOS involving the new mixing rules developed by Galicia-Luna et al. The model could not predict well the phase behavior near critical point of CO₂ + 1-butanol system. In the case of the system CO₂ + 2-butanol, the Pt-EOS with the new mixing rules predicted well the VLE near critical point at 335-431 K.