Vapor-liquid equilibrium for binary systems containing n-alkanes and cycloalkanes

In this study, VLE data for five binary systems comprising n-octane, n-nonane, methylcyclopentane, and methylcyclohexane were measured using the total pressure method at 393.15 K, 433.15 K, and 473.15 K. The NRTLHOC and the UNIQUAC-HOC models were used to successfully correlate all VLE data and determine binary interaction parameters. No azeotropic behavior was observed in any of the binary systems under the operating conditions. The predictive UNIFAC-DMD and COSMO-SAC models were implemented to predict binary VLE phase diagram and unveiled the mechanism of the separation efficiency of alkanes-cycloalkanes. Through the examination of the COSMO-SAC based molecular surface charge profile (cc-profile), the variance in non-hydrogen bonding segments within the cc-profiles of the analyzed alkanes determines both the strength of electrostatic interactions and the temperature-dependent VLE separation behaviors. The results indicate that cc-profile could be suggested as a good indicator to assess operating conditions of the alkanes VLE separation.

Automated summary

In this study, VLE data for five binary systems were measured and successfully correlated using models. The predictive models were used to predict the binary VLE phase diagram and explain the mechanism of separation efficiency. The strength of electrostatic interactions and temperature-dependent separation behavior were determined through the analysis of molecular surface charge distribution.