Liquid-Liquid Equilibria for the Extraction of Aromatics from Petroleum Naphtha Reformate by 1-Cyclohexyl-2- pyrrolidone/Triethylene Glycol Mixed Solvent

The phase equilibria for the extraction of aromatics from petroleum naphtha reformats (with a boiling range of 338-403K) using a mixed solvent of 1-cyclohexyl-2-pyrrolidone (CHP) and triethylene glycol (TEG) have been correlated using the universal function-group activity coefficients model (UNIFAC) group contribution model. The interaction parameters of CHP and TEG 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 have been fitted to the experimental concentrations of ternary systems that contain these groups. The extraction runs have been carried out at different temperatures, solvent compositions, and solvent-to-feed ratios. Experimental results were compared favorably with these predicted from the UNIFAC method. The optimum extraction conditions were determined by calculation of the minimum energy of separation. In this study these conditions were found to be at a 74%TEG solvent with a solvent-to-feed ratio of 5.6 on volume basis and at extraction temperature of 322K.