Predictive Correlation of Phase Equilibria for CO2 + n-Alkane Binary Systems Based on Cubic Mixing Rules

M. CISMONDI; S. B. RODRIGUEZ-REARTES; J. M. MILANESIO; M. S. ZABALOY

San Petersburgo

Simposio; 25rd European Symposium on Applied Thermodynamics (ESAT 2011); 2011

St.Petersburg State Univ., Russian Acad. Sci., the Mendeleev Russian Chem. Soc.

The qualitative and quantitative knowledge of phase equilibria and thermodynamic properties of mixtures containing CO2 and hydrocarbons are important, among other technological applications, for a better understanding of the mechanisms and consequently a better design of CO2 based enhanced oil recovery methods (CO2 -EOR). Binary mixtures of CO2 with n-alkanes, from the lighter to the heavier ones, have been studied by an important number of authors, both experimentally and using different types of models. An important degree of inaccuracy or scatter can be realized when comparing data from different sources, especially for the more asymmetric systems (long chain alkanes). At the same time, modeling studies have generally achieved only partially accurate results in the correlation of phase equilibrium data in wide ranges of temperature and pressure. During the last years we have dedicated some effort and a few publications to explore the possibilities that the flexible Cubic Mixing Rules (CMRs) offer for the modeling of asymmetric systems – where quadratic mixing rules fail – and to develop parameterization procedures. In this contribution, we present accurate results of predictive correlations for individual systems in wide ranges of temperature and pressure, based on a three-parameter cubic equation of state (the RK-PR EOS) coupled to CMRs. The results achieved so far for the correlation of the complete series of CO2 + n-alkane binary systems as a whole, with carbon number-dependent parameters, are also presented, discussing strengths and limitations. Future work includes the study of prediction and correlation of ternary mixtures phase equilibria.