Calculation of critical points for multicomponent mixtures containing hydrocarbon and nonhydrocarbon components with the PC-SAFT equation of state

In this work, the capability of the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state for predicting the critical points of multicomponent systems has been tested. The approach of Heidemann and Khalil was used to locating the critical points in any multicomponent mixture described by this equation of state. In order to improve the predictive ability of the PC-SAFT equation, the interaction parameters of 45 binary systems containing hydrocarbon (methane to n-decane) and nonhydrocarbon gases (CO2, N2), were estimated from binary vapor–liquid equilibrium data.Calculated gas–liquid critical points of 35 multicomponent systems containing three to 12 components were compared with experimental pressure and temperature critical data. The absolute average deviation values in critical temperature and critical pressure showed good agreement between the experimental data and those obtained from the PC-SAFT equation of state.