Estimation of liquid-liquid-vapor equilibria using predictive EOS models. 1. Carbon dioxide-n-alkanes

Ilya Polishuk, Jaime Wisniak, Hugo Segura

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


This study looks for the first time at the possibility of predicting liquid-liquid-vapor equilibria without preliminary resource to experimental data. For this purpose, the two most successful GE-based semipredictive models (PSRK and LCVM) and the global phase diagram (klGPD)-based semi-predictive approach (GPDA) have been implemented and compared. Although GE-based models require a significant amount of experimental data for evaluation of their parameters and prediction of the equilibrium, GPDA needs no more that 2-3 key experimental points. The superiority of GPDA, which considers the entire thermodynamic phase space, over the GE-based models, which are based on the fit of VLE data, is clearly demonstrated. Although the GE-based models fail to predict global phase behavior and to describe three-phase data accurately, GPDA yields exact predictions of the global phase behavior and accurate estimations of the composition and density of the vapor and the CO2-rich phases. In addition, it is accurate in describing the P-T projection of three-phase lines. All of the models considered are unable to predict the hydrocarbon-rich phase accurately. Presently, this problem cannot be solved without violating the predictive character of the model.

Original languageEnglish
Pages (from-to)1864-1874
Number of pages11
JournalJournal of Physical Chemistry B
Issue number8
StatePublished - 27 Feb 2003


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