Infinite dilution activity coefficients of C2–C8hydrocarbons in alkylcyclohexanes

Abstract

Infinite dilution activity coefficients (γ13∞) for mixtures of alkanes (C3–C8) in alkylcyclohexanes (C10–C18), and alkenes in alkylcyclohexanes (C10–C18), are reported. These were determined using gas–liquid chromatography where the alkylcyclohexanes form the stationary phase. A lattice theory for liquids, which has been previously applied to hydrocarbon mixtures, was used to calculate interchange energies from the experimental results. This theory was also applied to existing (cyclohexane+alkane) and (alkane+nonadecylcyclohexane) data with these interchange energies compared with values determined from the γ13∞results reported in this work. There was good agreement (1 to 5 per cent) between predicted and experimental γ13∞results for (alkane+alkylcyclohexane) mixtures. However, this was found not to be the case for the (alkene+alkylcyclohexane) mixtures where the alkene segment —CH=CH2was assumed to behave similarly to the —CH2—CH2— segment. The differences between experimental and theoretical γ13∞values for these types of mixtures were of the order of 30 per cent when using interchange energies derived from (alkane+alkylcyclohexane) mixtures.