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

Abstract

Vapor–liquid equilibrium (VLE) and vapor–liquid–liquid 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–Tobias 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.

Vapor-Liquid Equilibrium at Several Experimental Conditions of the Binary Mixtures Methyl Lactate with n-Alkanols

“…The experimental normal boiling points and vapor pressures at T = 323.15 K of pure components, T b and pº, were determined using the same circulating apparatus used for mixtures measurement and they are listed in Table 2 along with some literature data [12,[16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Vapor–Liquid Equilibria Measurements for the Ninen-Alkane/Ketone Pairs Comprising 2-, 3-, and 4-Heptanone withn-Octane,n-Nonane, andn-Decane

“…The still was previously modified to house an ultrasonic homogenizer adjacent to the feed heater to aid in the measurement of vapor−liquid−liquid equilibrium data in previous work. 6 Although the homogenizer was not used in this work, it was necessary to keep it fitted to the still to keep the unit sealed. Equilibrium was achieved rather quickly (approximately 1 h) due to continuous circulation of both vapor and liquid phases, according to the Gillespie principle, as well as the intense mechanical stirring of the relatively small liquid inventory.…”

Separation of the Mixture 2-Propanol + Water by Heterogeneous Azeotropic Distillation with Isooctane as an Entrainer

“…Further papers related to HAD for the separation of aqueous alcoholic mixtures can also be mentioned [30,[43][44][45][46][47][48][49][50][51][52][53][54][55]. Gomis et al [43], for instance, have analyzed the n-butanol + water + n-hexane system, whilst Pienaar et al [44] have considered the VLLE and the VLE for the ternary systems n-propanol + water + DIPE and n-propanol + water + isooctane. Indeed, alternative entrainers to the carcinogenic benzene need to be found.…”