Correlation of K-factors for mixtures of hydrogen and heavy hydrocarbons

K-factors for hydrogen-heavy hydrocarbon mixtures are becoming increasingly important in new industrial applications, particularly in coal liquefaction. When equations of state such as Soave's are used to fit hydrogen-heavy hydrocarbon binary data, unrealistic binary interaction parameters k_ij are required because equilibrium ratios are not sensitive to k_ij for highly asymmetric binary systems containing a highly supercritical component.Reliable representation of experimental results can be obtained by modifying the composition dependence of the covolume parameter b for the mixture. The modification introduces a binary parameter E_Hj which has a physically reasonable size. Upon adjusting E_Hj to fit the binary data (setting k_ij = 0), good results are obtained for seven hydrogen-heavy hydrocarbon binaries.