Measuring vapour-liquid equilibria (VLE) using benchtop NMR.

Abstract

Vapour-liquid equilibria data are essential in the design of chemical processes. Existing measurement techniques require relatively large quantities of material, making them challenging to apply to new processes for expensive or toxic species. We report a novel method for measuring vapour-liquid equilibrium data of binary liquid mixtures using benchtop 1H NMR spectroscopy close to ambient pressure. Vapour and liquid compositions were directly obtained from NMR measurements, showing good agreement with predictions from state-of-the-art thermodynamic models. Furthermore, following calibration, the benchtop NMR results were used to obtain measurements of vapour pressure. Results were obtained from as little as 0.5 mL of sample, extending the range of systems for which vapour-liquid equilibria can be measured.

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