Modeling VLE of H₂ + Hydrocarbon Mixtures Using a Group Contribution SAFT with a <i>k</i>_<i>ij</i> Correlation Method Based on London’s Theory

A group contribution perturbed-chain statistical associating fluid theory (GC-PC-SAFT) equation of state (Tamouza et al. <i>Fluid Phase Equilib</i>. <b>2004</b>, <i>222</i>−<i>223</i>, 67−76) combined with a recent method for correlating <i>k_ij</i> using only pure compound parameters (NguyenHuynh et al. <i>Ind. Eng. Chem. Res.</i>, <b>2008</b>. <i>47(22)</i>, 8847−8858) is extended here to model vapor−liquid phase equilibria of H₂ + alkanes and H₂ + aromatics mixtures. The correlation of <i>k_ij</i> is inspired by London’s theory of dispersive interactions, and uses “pseudo-ionization energies” <i>J</i>_<i>i</i> and <i>J</i>_<i>j</i> of compounds <i>i</i> and <i>j</i> 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.; <i>Proc., 6</i>^<i>th</i> <i>World Pet. Congress</i>, 1963, 169−181), which is often used by process engineers for hydrogen and hydrocarbon mixtures