Separation of propylbenzene and n-alkanes from their mixtures using 4-methyl-N-butylpyridinium tetrafluoroborate as an ionic solvent at several temperatures

Liquid–liquid extraction is the most common method for separation of aromatics from their mixtures with n-alkanes hydrocarbons. An ionic liquid (IL), 4-methyl-N-butylpyridinium tetrafluoroborate [(mebupy)(BF4)], was evaluated as solvent for this separation. Liquid equilibria (LLE) for 2 ternary systems comprising tetradecane, or hexadecane + propylbenzene + [(mebupy)(BF4)] were measured over a temperature range of 313–333 K and atmospheric pressure. The reliability of the experimental data was evaluated using the Othmer–Tobias correlation. The effect of temperature, n-alkane chain length and solvent to feed ratio upon solubility, selectivity, and distribution coefficient were investigated experimentally. In addition, the experimental results were regressed to estimate the interaction parameters between each of the 3 pairs of components for the UNIQUAC and the NRTL models as a function of temperature. Both models satisfactorily correlate the experimental data, however the UNIQUAC fit was slightly better than that obtained with the NRTL model.

► 4-Methyl-N-butylpyridinium tetrafluoroborate [(mebupy)(BF4)] was evaluated as an ionic solvent for the separation of aromatics from their mixtures with n-alkanes hydrocarbons.
► The reliability of the experimentally measured tie line data can be ascertained by applying the Othmer–Tobias correlation.
► The effect of temperature, n-alkane chain length and solvent to feed ratio upon solubility, selectivity, and distribution coefficient were investigated experimentally.
► The UNIQUAC and the NRTL models as a function of temperature satisfactorily correlate the experimental data.