Liquid-liquid equilibria for the extraction of aromatics from naphtha reformate by dimethylformamide/ethylene glycol mixed solvent

The phase equilibria for the extraction of aromatics from naphtha reformate (b.p. 60–135°C) in a mixed solvent of dimethylformamide (DMF) and ethylene glycol (EG) have been correlated using the UNIFAC group contribution model. The interaction parameters of DMF and EG with different hydrocarbon groups present in the reformate, such as CH2 (paraffinic CH2), ACH (aromatic CH) and ACCH2 (aromatic CCH2), and each of the two solvents were fitted to experimental concentrations of ternary systems containing these groups. The extraction runs were carried out at different temperatures, solvent compositions and solvent-to-feed ratios. The experimental results compared favorably with those predicted from the UNIFAC method. The minimum required energy for separation was achieved at 57°C using a 44% EG solvent with a solvent-to-feed ratio of 2.2 on a volume basis.