Vapor–Liquid Equilibria of the CH₄ + CO₂ + H₂S Ternary System with Two Different Global Compositions: Experiments and Modeling

Abstract

The vapor–liquid equilibrium for two mixtures containing methane, carbon dioxide, and hydrogen sulfide was determined experimentally by a static-analytic method. Thirty-one data points were acquired for a range of temperatures from 243 to 333 K at pressures up to 11 MPa. The measured data were correlated with the Peng–Robinson equation of state (EoS) and different mixing rules, which led to the conclusion that a cubic EoS could simultaneously predict the existence of a three-phase region and two critical points on the constant-composition, two-phase boundary curve.