Vapor–Liquid Equilibrium of the Hydrogen Sulfide (H ₂ S)–Propylene (C ₃ H ₆ ) Binary System: Experimental and Modeling Study

The study of the phase behavior of the binary system hydrogen sulfide (H2S)–propylene (C3H6) is necessary for the optimization of gas sweetening processes and petrochemical streams. This study presents new isothermal vapor–liquid equilibrium (VLE) measurements for this system at 278.21, 298.12, 323.06, and 348.13 K, at pressures up to 5.8 MPa. The data were obtained using a precise static-analytic method with two magnetic capillary samplers (ROLSI(R)) for phase analysis by gas chromatography. The measurement uncertainties are u(T)= 0.02 K for temperature, u(P)= 0.0009 MPa for pressure, and u(x,y) = 0.001 for molar compositions. To model this data, a ϕ–ϕ approach utilizing the translated consistent Peng–Robinson (tc-PR) equation of state was used. For the liquid phase, we compared the classical van der Waals mixing rules against the Wong-Sandler mixing rules coupled with the NRTL model. Subsequently, a multiparametric equation of state was utilized to extend the analysis. After optimizing the parameters of each model by fitting them to experimental data, the final models accurately describe the phase behavior of the system. Their reliability and suitability for industrial process design and simulation are thereby demonstrated.