Vapor–Liquid Equilibria for Water + Propylene Glycols Binary Systems: Experimental Data and Regression

Abstract

The vapor−liquid equilibria (VLE) data are essential for the design of distillation columns to separate propylene glycols mixtures, obtained via the hydrolysis of 1,2-epoxy propane. In this study there are reported data for four binary systems involved, such as water + propylene glycols. VLE data have been measured in the temperature range (295.15 to 460.15) K and pressure up to 34.529 kPa for the following binary systems: water +1,2-propanediol (monopropylene glycol, MPG), water +1-(2-hydroxypropoxy)propan-2-ol (dipropylene glycol, DPG), water +2-[2-(2-hydroxypropoxy)propoxy]propan-1-ol (tripropylene glycol, TPG), and water +2-(2-[2-(2-hydroxypropoxy)propoxy]propoxy)propan-1-ol (tetrapropylene glycol, TePG). The equipment used was a static apparatus built in our laboratory. The only literature data available for these systems were for the water + MPG binary system. The experimental data obtained were correlated with the NRTL model. The results showed a fairly good agreement between the model and the experimental data with a maximum deviation in composition terms of 3%.

Synthesis and simulation of a distillation columns system for the propylene glycols mixtures separation

“…The VLE data for the water + propylene glycol binary systems in the temperature range of 295.15 to 460.15 K and pressure up to 34.529 kPa and for the propylene glycol + propylene glycol binary systems in the temperature range of 350.15 to 510.15 K and pressures up to 34.374 kPa were published in our previous studies. 34,35 The VLE data for the mixtures water + MPG and MPG + DPG 33 were the only equilibrium data for these systems, available in the literature, at the time when we have accomplished the above experimental data. The VLE experimental data presented in our previous works were determined at low pressures because the separation process we propose in this study can operate only in these conditions.…”

“…The VLE experimental data were regressed to obtain binary interaction parameters for NRTL (nonrandom two-liquids) activity coefficients. [36][37][38][39] The simulation of the distillation columns system for separation of the propylene glycols mixtures was performed with the PRO/II 33 software using the specific correlations for the TePG properties 2 and using NRTL 36 thermodynamic model that contain the resulted binary interaction parameters reported by Fendu and Oprea 34,35 for the binary mixtures formed by the components involved.…”

Experimental and Regression Vapor–liquid Equilibrium Data for Ethanol + Dipropylene Glycol Binary System

“…The validation of the procedure for the VLE determination and the data obtained with this apparatus was achieved earlier by the determination of the VLE data for the water + DPG binary system. For the binary system water + DPG, the VLE data were obtained by a static apparatus described by Fendu and Oprea [33]. The data obtained with the static apparatus illustrated in Fig.…”

“…The data obtained with the static apparatus illustrated in Fig. 1 were compared with those obtained with the apparatus described in [33] for the water + DPG binary. They were in good agreement, as can be observed in Fig.…”

“…In this work, DPG is studied as a possible extractive agent for the extractive distillation process applied for ethanol + water separation. Considering that dipropylene glycol wasn't mentioned in the literature as an extractive agent for ethanol, but just the propylene glycol [32], it was found that there are no equilibrium data published until now between ethanol and dipropylene glycol, but only for water and dipropylene glycol [31,33]. We determined the vapor-liquid equilibrium (VLE) data for the binary system ethanol + dipropylene glycol, and the data are presented in this work.…”