High pressure phase behavior of methanol + ethylene: Experimental measurements and CPA modeling

• Vapor–liquid equilibrium data were obtained experimentally for methanol + ethylene.
• The cubic plus association (CPA) equation of state was used to model this system.
• The effect of solvation was also investigated in the CPA model.
• Deviations from experimental data are less for CPA when solvation is considered.
• CPA can predict the phase behavior of methanol + ethylene better than the popular PR and SRK.

High pressure–temperature isopleths were obtained, experimentally, for the binary system of methanol + ethylene within a temperature and pressure range of 293–373 K and 38–119 bar, respectively. The experimental results were modeled using the Cubic-Plus-Association (CPA), Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The ability of the CPA model to predict the phase behavior of methanol + ethylene is much better than the SRK and PR models. However, even though the p–T diagrams indicate that the CPA equation of state correlates well with the experimental results, by increasing ethylene concentrations, the errors of CPA increase due to the solvation that occurs in methanol + ethylene systems. In this work, the effect of solvation is also investigated. Results show that deviations from experimental data are less for CPA with solvation than for the CPA without solvation. Correlations are presented for the binary interaction (kij) and the association volume (βAiBj) parameters to model the phase behavior of methanol + ethylene, as both of these parameters were indicated to be temperature-dependent.

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