Modeling VLE of H2+ Hydrocarbon Mixtures Using a Group Contribution SAFT with akijCorrelation Method Based on London’s Theory

Abstract

A group contribution perturbed-chain statistical associating fluid theory (GC-PC-SAFT) equation of state (Tamouza et al. Fluid Phase Equilib. 2004, 222−223, 67−76) combined with a recent method for correlating kij using only pure compound parameters (NguyenHuynh et al. Ind. Eng. Chem. Res., 2008. 47(22), 8847−8858) is extended here to model vapor−liquid phase equilibria of H2 + alkanes and H2 + aromatics mixtures. The correlation of kij is inspired by London’s theory of dispersive interactions, and uses “pseudo-ionization energies” Ji and Jj of compounds i and j as adjustable parameters. The GC-PC-SAFT parameters for alkanes and aromatics were reused from previous works when available. Otherwise, the missing parameters were estimated by regression of corresponding pure vapor−liquid equilibrium (VLE) data. Those of H2 were determined in this work by correlating some VLE data of H2 + n-alkane systems. Using the parameters thus obtained, the phase envelopes of other H2 + alkane and H2 + aromatic systems were fully predicted. The prediction tests were as comprehensive as possible. Correlations and predictions are qualitatively and quantitatively satisfactory. The deviations are within 5−6%, that is, comparable to those obtained on previously investigated systems. Mixtures containing H2 are modeled here with deviations that compare well with those of the Grayson−Streed model (Grayson, H.G.; Streed, C.W.; Proc., 6th World Pet. Congress, 1963, 169−181), which is often used by process engineers for hydrogen and hydrocarbon mixtures.