Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Vapor-liquid equilibrium measurements for the binary system CO2 + CO are reported at 253, 273, 283 and 298 K, with estimated standard uncertainties of maximum 9 mK in temperature, maximum 3 kPa in pressure, and maximum 0.001 in the mole fractions of the phases in the mixture critical regions, and 0.0003 in the mole fractions outside the critical regions. These measurements are compared with existing data. Although some data exist, there are little trustworthy literature data around critical conditions, and the measurements in the present work indicate a need to revise the parameters of existing models. The data in the present work have significantly less scatter than most of the literature data, and range from the vapor pressure of pure CO2 to close to the mixture critical point pressure at all four temperatures. With the measurements in the present work, the data situation for the CO2 + CO system is improved, enabling development of better equations of state for the system. A scaling law model is fitted to the critical region data of each isotherm, and high accuracy estimates for the critical composition and pressure are found. The Peng-Robinson EOS with the alpha correction by Mathias and Copeman, the mixing rules by Wong and Sandler, and the NRTL excess Gibbs energy model is fitted to the data in the present work.