Activity coefficients of solutions of C4—C8 hydrocarbons in n-tetracosane and n-dotriacontane

Abstract

The activity coefficients at infinite dilution for a series of C₄—C₈ hydrocarbons in n-tetracosane, mainly at 60°C and in n-dotriacontane at 75°C have been studied by gas-liquid chromatography (G.L.C.). Mixed second virial coefficients have been obtained for hydrocarbon and nitrogen carrier gas mixtures.

The activity coefficients have been discussed in terms of equations of the Flory-Huggins type. The interaction parameters for the n-alkanes have been discussed in terms of “end-group-middle-group” interactions as in an earlier paper. The activity coefficients of the n-alkanes have also been compared with the principle of congruence. The agreement with theory is good in both cases. The relationship between Bellemans and Mat's formulation of the principle of congruence and the quasi-lattice theory is discussed.

The mixed second virial coefficients (B₁₂) have been compared with the values predicted by the principle of corresponding states using the geometric mean and Hudson and McCoubrey combining rules to estimates the pseudo critical volume and temperature. The Hudson-McCoubrey rule is superior to the geometric mean rule in predicting the B₁₂ values.