Vapor鈥揕iquid鈥揕iquid Equilibria Measurements for the Dehydration of Ethanol, Isopropanol, and n-Propanol via Azeotropic Distillation Using DIPE and Isooctane as Entrainers

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• 作者：Cornelia Pienaar ; Cara E. Schwarz ; Johannes H. Knoetze ; Andries J. Burger
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2013
• 出版时间：March 14, 2013
• 年：2013
• 卷：58
• 期：3
• 页码：537-550
• 全文大小：492K
• 年卷期：v.58,no.3(March 14, 2013)
• ISSN：1520-5134

文摘

Vapor鈥搇iquid equilibrium (VLE) and vapor鈥搇iquid鈥搇iquid equilibrium (VLLE) data were measured for the ethanol/diisopropyl ether (DIPE)/water, n-propanol/DIPE/water, and n-propanol/2,2,4-trimethylpentane (isooctane)/water systems at 101.3 kPa. The data were carefully measured in a Guillespie type still, equipped with an ultrasonic homogenizer. The VLE data were found to be thermodynamically consistent, and the LLE part of the VLLE data followed a regular profile according to the Othmer鈥揟obias correlation. VLLE were observed in the temperature ranges of (334.19 to 336.29) K, (335.31 to 345.76) K, and (347.74 to 352.31) K for the ethanol/DIPE/water, n-propanol/DIPE/water, and n-propanol/isooctane/water systems, respectively. These VLLE regions encompassed wide ranges for water and entrainer composition, with alcohol mole fractions of up to approximately 0.4. The ethanol/DIPE/water and n-propanol/isooctane/water systems displayed ternary heterogeneous azeotropes at (334.19 and 347.74) K, respectively. However, no ternary heterogeneous azeotrope was found for the n-propanol/DIPE/water system. The measured data were subsequently modeled in Aspen Plus with the nonrandom two-liquid (NRTL), universal functional UNIFAC(VLE), UNIFAC(LLE), and universal quasichemical UNIQUAC activity coefficient models, applying the default regression parameters built into Aspen Plus. UNIFAC(VLE) predicted the ethanol/DIPE/water system most accurately, while UNIQUAC performed the best for the n-propanol/DIPE/water. However, none of these models could predict the n-propanol/isooctane/water system with acceptable accuracy. The results of this study strongly support proposals that DIPE or di-n-propyl ether (DNPE) could be used as effective entrainers for alcohol dehydration, replacing the more traditional entrainers like benzene and cyclohexane.