A robust setup for efficient characterization of multicomponent vapor-liquid equilibria using Raman spectroscopy

Vapor-liquid equilibrium (VLE), a crucial thermodynamic property in diverse industrial processes, assumes paramount significance in the development, optimization, and operation of separation processes and various applications. Despite their central role, large sample volumes, long measurement times and the handling of the apparatus are a challenge for the precise determination of VLE data. In response to these challenges, we present an innovative Raman spectroscopy-based measurement setup that enables fast, accurate and user-friendly characterization of VLE. The application of Raman spectroscopy enables non-invasive analysis of vapor and liquid-phases in small sample volumes (<3 ml) for multiple VLE data points. The usage of a compact isothermal VLE measurement cell ensures rapid and reliable VLE control. The combination of the equilibrium cell with a highly confocal fiber-coupled Raman probe in backscattering configuration and a high-throughput spectrometer establishes an efficient setup for quantifying VLE data in a broad range of conditions. The setup has been validated for vapor pressure curves of methyl tert‑butyl ether (MTBE), isooctane (2,2,4-trimethylpentane) and cyclohexane for a temperature range of 283.15 K to 333.15 K and the measurement of the binary VLE MTBE-isooctane at 318 .15K. the setup allows a highly efficient access to VLE data of industrial relevance.