Liquid–Liquid Equilibria for Dipropylene Glycol–Hydrocarbon Binary Systems: Experimental Data and Regression

• Published in: Journal of chemical and engineering data Vol. 57; no. 12; pp. 3690 - 3695
• Main Authors: Nicolae, Marilena, Oprea, Florin
• Format: Journal Article
• Language: English
• Published: American Chemical Society 13.12.2012
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je3009039

Propylene glycols (mono- and di-) have an important potential as solvents in liquid–liquid extraction of aromatics and in azeotropic distillation. Literature and databases provide few accurate experimental data on liquid–liquid and vapor–liquid equilibria in systems consisting of propylene glycols and hydrocarbons (paraffinic, naphthenic, and aromatic hydrocarbons). However, an increasing interest in this field can be observed in recent years. This paper reports the results of an experimental study on the liquid–liquid equilibria in binary systems consisting of dipropylene glycol and paraffinic, naphthenic, and aromatic hydrocarbons with six, seven, and eight atoms of carbon. The experimental data were obtained in a high-precision thermostatic equilibrium cell. The first and most important result was that all normal paraffinic and naphthenic hydrocarbons are partially miscible with dipropylene glycol (4-oxa-2,6-heptanediol), whereas aromatics are completely dissolved. To obtain the binary interaction parameters of the Non-Random Two-Liquid (NRTL) activity coefficients, a regression procedure was applied to the experimental data (only for normal paraffinic and naphthenic hydrocarbon–dipropylene glycol systems) for each measured system. The NRTL parameters of the partially miscible binaries (complemented by the NRTL parameters for completely miscible binaries) can be subsequently used for simulations of liquid–liquid extraction, solvent recovery, and extractive-distillation processes.