Low-temperature regeneration of solvent in extraction of aromatic hydrocarbons with propylene carbonate

Abstract

1. A study has been made of phase equilibria in ternary systems of pentadecane-aromatic hydrocarbons — propylene carbonate, at 20°C. Distribution coefficients of the aromatic hydrocarbons between phases have been calculated, and these have been used to calculate the approximate pentadecane/feedstock ratio required for complete extraction of an individual aromatic hydrocarbon. 2. The results of experiments conducted with a countercurrent column on the reextraction of aromatic hydrocarbons from a real extract solution by means of pentadecane have shown that, with a 1/1 ratio of pentadecane to feedstock and a reextraction zone height corresponding to 3–4 theoretical extraction stages, extraction of the aromatic hydrocarbons is essentially complete. 3. The pentadecane-aromatic hydrocarbon mixture can be separated in low-efficiency fractionating columns, owing to the large difference in boiling points.