Generalized Correlation of Binary Interaction Parameters in Cubic Equations of State for Hydrocarbon/CO 2 , Hydrocarbon/H 2 S and CO 2 /H 2 S Systems Oscar M. Barrios, Claudio Olivera-Fuentes, Freddy L. Figueira * TADiP Group, Department of Thermodynamics and Transport Phenomena Simón Bolívar University AP89000, Caracas 1081, Venezuela freddyfigueira@usb.ve In the present work, we develop a predictive corresponding-states correlation for the binary interaction parameters of systems composed of hydrocarbons (HC), up to C 10 , with CO 2 and H 2 S. Experimental data were collected from the literature for 12 HC/CO 2 systems (1017 data points for 90 isotherms), 7 HC/H 2 S systems (293 data points for 27 isotherms), and the CO 2 /H 2 S systems (61 data points for 19 isotherms). Optimal k ij were computed using the isofugacity method of Paunović et al. Computations were made for the van der Waals, Redlich-Kwong and Peng-Robinson equations of state, with the cohesion functions of Soave, Gibbons and Laughton, Stryjek and Vera, Twu et al., and our own group. Analysis of the results showed that k ij are essentially the same for each binary pair and equation of state, regardless of the cohesion function used, thus making them true system properties. Average deviations obtained with the present correlation range from 2.5% to 4.5% for compositions, and from 1.5% to 4.0% for pressures, depending on the equation of state and type of binary pair. The correlation has also been used successfully in predicting vapor-liquid equilibria of ternary and higher mixtures involving these same components. 1. Introduction Cubic equations of state are still widely used for representing phase equilibria of mixtures of industrial importance, notably in the natural gas and petroleum industry where there are mixtures of hydrocarbons and inorganic gases such as CO 2 , H 2 S, H 2 and N 2 . Their applicability is based on their algebraic simplicity, versatility and precision. The general form for the 2P1T (2 parameters, one dependent on temperature) cubic equations of state (CEOS) is: (1) where a and b, the cohesion parameter and the covolume, are specific to each substance and are calculated from their critical properties as: (2)