Vapor–Liquid Equilibria of Glycerol, 1,3-Propanediol, Glycerol + Water, and Glycerol + 1,3-Propanediol

Abstract

Vapor−liquid equilibria of two compounds, glycerol (or 1,2,3-propanetriol) and 1,3-propanediol, and two mixtures, glycerol + water and glycerol + 1,3-propanediol, were determined using a static apparatus. The obtained pressure values range from 6 Pa to 45 kPa for the compounds and from (32 to 163) kPa for the mixtures. From the temperature dependence of the vapor pressures, the molar enthalpies of vaporization at the mean temperature of the experimental range were derived from the Clausius−Clapeyron equation. From these results the standard enthalpies of vaporization at T = 298.15 K were calculated. The experimental data of the mixtures were correlated using the nonrandom two-liquid (NRTL) model. ■ INTRODUCTIONPetroleum reserves reduction and the increase of environmentally friendly comportment promote the development of new green energy research. Fatty acid methyl ester, commonly known as biodiesel, is derived from the triglyceride transesterification. The reaction generates glycerol as a byproduct in high quantities (1 mole of glycerol for every 3 moles of methyl esters synthesized, about 10 wt % of the total product). Glycerol valorization is crucial for the viability of biodiesel plant. One way for glycerol valorization could be its transformation in 1,3-propanediol which is a valuable chemical used in polyethylene and polyurethane production. 1−4 The development of the chemical processes (design and optimization) requires knowledge of physicochemical properties such as vapor pressures, the boiling point, and the vaporization enthalpy for all of the compounds and mixtures involved in the process. These data are often scarce or not available. So, predictive models such as the universal functional activity coefficient (UNIFAC) are largely used. 5,6 But when the systems present a weak nonideality the obtained results are not reliable. In this work, we were interested in the vapor pressures of two compounds and two mixtures, respectively: glycerol, 1,3-propanediol, water + glycerol, and 1,3-propanediol + glycerol. Experimental results were fitted by the Antoine and Clapeyron equations and compared with the available literature data. The two mixtures were correlated using the nonrandom two-liquid (NRTL) equation. ■ EXPERIMENTAL SECTIONMaterials. Glycerol (or 1,2,3-propanetriol) and 1,3-propanediol were purchased from Aldrich. Their purity was 99 %. Ultrapure water with a resistivity of 18 MΩ·cm, obtained with a Milli-Q system, was used.Apparatus and Procedure. Vapor pressure measurements were carried out using two static apparatuses: "low pressure" and "middle pressure" measurement apparatuses. The low pressure apparatus has been described in several articles, and the details of the experimental procedure can be found elsewhere. 7,8 Shortly, the apparatus is equipped with a differential manometer from MKS, type 670 model 616A, and a Rosemount pressure sensor (model 1151 DPE 22S2). The measurement range of the apparatus is comprised between 0.5 Pa and 200 kPa for the pressure and between 233 K and 463 K for the tem...

Vapor–Liquid Equilibrium of Water + Ethanol + Glycerol: Experimental Measurement and Modeling for Ethanol Dehydration by Extractive Distillation

“…The calculated results are compared with the experimental and literature values and shown in Figure 8. As γ 13 ∞ is concerned, the results of the present correlation are in good agreement with the experimental values and are slightly larger than the literature values of Ikari and Ayabe (cited in Kojima et al 21 ) and the calculated values of Mokbel et al 23 Further, the literature values of Bestani and Shing 25 appears to be unusually great, whereas the correlations of Souza et al, 3 Pla-Franco et al, 4 and APV80 VLE-IG provide values that are unusually small. Because the infinite dilution state is closely related to the process of glycerol recovery, such large deviations in γ 13 ∞ would have significant impact on the design of the recovery unit.…”

Benchmark thermodynamic properties of 1,3-propanediol: Comprehensive experimental and theoretical study

“…But it has turned out that new vapour pressures measured by static method recently [14] were slightly higher (see figure S1) in comparison to our published transpiration results [4]. In order to ascertain a vapour pressure dataset, in this work we have repeated transpiration experiments on 1,3-propanediol especially at temperatures above 333 K where the discrepancies were more apparent.…”

“…A general good agreement was observed for the available in the literature absolute vapour pressures. In the meantime, an extended GC-correlation study of a,x-alkanediols was published by Chickos et al [13], as well as a very careful vapour pressure measurements were reported from the static method just recently [14]. We also overlooked in reference [4] vapour pressures measured by ebulliometry [15] and by the thermogravimetry [16].…”

Thermodynamic properties of glycerol: Experimental and theoretical study

“…1is not informative enough. More detailed insight in the quality of vapor pressures measured with different methods [14,[16][17][18][19][20][21][22][23][24][25] can be obtained from the "arc representation" developed by Oonk et al [26][27][28].The main idea of this approach is to collect all available data in a possibly broad temperature range and to approximate vapor pressures at the beginning and the end of the temperature range with the linear equation.…”

“…- [19];  -Knudsen [20]; □ -TGA [22]; ○ -Knudsen [21]; △ -static method [25]; ▽ -TGA [23]; ▷ -ebulliometry [17]; ◁ -not available method [24];  -ebulliometry [16];…”