Statistical Associating Fluid Theory Equation Of State Research Articles

(Methanol + ethene): phase behavior and modeling with the SAFT equation of state

Pressure (composition) isotherms for (methanol + ethene) were obtained at the temperatures (303.65, 333.15, 382.35, and 431.95) K. The critical-mixture pressures from these isotherms are in good agreement with the critical-mixture results obtained by Brunner (J. Chem. Thermodynamics1985, 17, 871). The experimental results are modeled with the statistical associating-fluid theory (SAFT), which explicitly accounts for methanol-methanol association and for ethene-methanol complex formation. The SAFT model, with a single temperature-independent mixture parameter fitted to one isotherm, correctly predicts the type of phase diagram exhibited by (methanol + ethene). However, calculated critical pressures are as much as 4 MPa greater than observed values. The Peng-Robinson equation of state is not capable of even qualitatively predicting the correct phase behavior with two temperature-independent mixture parameters, because it cannot account for either methanol-methanol self-association or ethene-methanol complexing.