Aspects of the thermogravimetric analysis of liquid mixtures as predictive or interpretation tool for batch distillation

Antonio Tripodi,Ilenia Rossetti

doi:10.1007/s10973-021-10990-1

Antonio Tripodi, Ilenia Rossetti

Open Access

https://doi.org/10.1007/s10973-021-10990-1

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Abstract

The thermogravimetric analysis when applied to liquid binary mixtures of acetonitrile–water and methanol–water reproduces the whole course of a batch distillation with an appreciable saving of time and materials. The experimental mass and energy balances correlate with good approximation to the vapor–liquid equilibrium compositions without the need of gas-phase measures or thermodynamic models. This technique was here applied for the first time as fast method for distillation design and complementary tool for DSC boiling-point measurements.

Highlights

The collection of vapor–liquid equilibrium (VLE) data is essential for the distillation design, and to provide the inputs to many first-principle or semi-empirical models capable to calculate other properties [1, 2].The long-established vaporization and condensation apparatuses, coupled to analytical techniques such as gasand mass chromatography, have been continuously evolving [3,4,5] and providing valuable information [6, 7]
The temperature rise is slow enough to eliminate all the acetonitrile before the saturation condition for pure water is met; a second-phase transition is eventually detected. This double regime can be suppressed if the heating ramps becomes faster. This behavior is not clearly recognized when the acetonitrile and methanol initial contents are below 20–30%, though mass fractions down to the 15–20% can be retraced via the data analysis
Thermogravimetric experiments performed with open pans can split the evaporation regime of a binary mixture in two parts, which represent, respectively, the distillates and the residues that would be obtained with a batch distillation at null reflux ratio

Summary

Introduction

The collection of vapor–liquid equilibrium (VLE) data is essential for the distillation design, and to provide the inputs to many first-principle or semi-empirical models capable to calculate other properties [1, 2]. The long-established vaporization and condensation apparatuses, coupled to analytical techniques such as gasand mass chromatography, have been continuously evolving [3,4,5] and providing valuable information [6, 7] Other methods, such as thermogravimetric analysis (TGA) [8, 9] and differential scanning calorimetry (DSC), have been lately used as complementary tools, because they are much faster and employ very limited quantity of substance [10]. All the TGA–DSC scans were performed by a MettlerToledo TGA/DSC/3 + 1100 (horizontal loading) unit with open crucibles (standard type, volume: 150 μL), with a purging flow of Nitrogen (5 mL min−1) and a temperature increase from 30 to 150 °C at the low heating speed of 5 °C min−1.

Results and discussion

Literature data

Conclusions