Liquid–Liquid Phase Behavior of Ternary Mixtures: n‑Dodecane, n‑Hexadecane, and Ethanol

• Published in: Journal of chemical and engineering data 2022-08, Vol.67 (8), p.2004-2014
• Main Authors: Wagenfeld, Sabine, Schröer, Wolffram, Rathke, Bernd
• Format: Article
• Language: English
• Subjects: Liquid-Liquid Equilibria and Vapor-Liquid-Liquid Equilibria
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/acs.jced.1c00943

Fuel blending requires knowledge of the thermophysical properties of the single components and its mixtures. Because of the complexity of real systems much expertise in this area is based on empirical results and experience. To provide background for deriving well-founded structure–property relationships, this paper reports data on the mutual solubility of ternary mixtures of n-dodecane, n-hexadecane, and ethanol. These compounds form a region of limited miscibility in the multidimensional phase space. The cloud point method is applied for determining liquid–liquid phase equilibria (LLE) of three pseudobinary mixtures of the selected n-alkanes. They mimic the binary mixtures by an appropriate selection of the mixing ratios of the two alkanes binary mixtures with the normal alkanes n-tridecane, n-tetradecane, and n-pentadecane. The pseudobinary systems show upper critical solution temperatures (UCSTs), which vary congruent to the mixing ratios of the two alkanes in the limits defined by the UCSTs of the binary systems of n-dodecane/ethanol and n-hexadecane/ethanol, respectively. A numerical analysis of the LLE allows elucidating the behavior of the n-alkane mixtures. Their UCSTs show a small deviation from a linear mixing rule. By an evaluation of the LLE of the pseudobinary mixtures, tie lines are estimated. The LLE of the pseudobinary mixtures enable construction of the isobaric temperature–composition phase prism including the critical line and its end points as well as the estimation of tie lines. This study provides the basic data required for optimizing and customizing extraction processes or processing of intermediate products obtained by, for example, a catalytic production of hydrocarbons.