The extraction of aromatics using n-methylpyrrolidone: Liquid-liquid equilibrium determination and mechanism exploration

LLE data of cyclooctane/3-methylpentane + benzene/toluene + n-methylpyrrolidone (NMP) at 298.15 K and 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Hand equations were adopted to validate the reliability of LLE data, where the correlation coefficients (R2) were close to unity, indicating the high reliability of the experimental data. The experimental data were analyzed using the distribution coefficient (D) and separation factor (S), and the effect of NMP extracting benzene and toluene from aromatics was explored. Meanwhile, the reason for the different extraction efficiencies of benzene and toluene using NMP was analyzed by quantum chemical calculations. The NRTL and UNIQUAC thermodynamic models were used to correlate the liquid-liquid equilibrium data, and the relevant binary interaction parameters were obtained. The calculated root mean square deviation (RMSD) were all less than 0.0063, indicating that the obtained binary interaction parameters can be used to simulate and calculate the extraction of aromatics using NMP.