Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Experimental vapor-liquid equilibrium data are of major importance for the chemical industry. However, the measurement of vapor-liquid equilibrium data still requires significant experimental effort. Therefore, we present a novel setup and measurement procedure for the rapid determination of isothermal vapor-liquid equilibria using only milliliter samples. The compositions of both liquid and vapor phases are analyzed using Raman spectroscopy. The measurement setup is successfully validated by reproducing vapor pressures of four pure substances and binary vapor-liquid equilibrium data of methyl tert-butyl ether (MTBE) and 2,2,4-trimethylpentane (iso-octane) at T=318.1 K as test system from literature. The vapor pressures of MTBE, ethanol, iso-octane and toluene agree with literature data within the measurement uncertainties. The measured binary vapor-liquid equilibrium data are modeled using the PCP-SAFT equation of state. Phase equilibrium data calculated from PCPSAFT are compared to experimental data from literature. The data deviate by less than 1% in terms of pressure and vapor phase composition for given temperature and liquid phase composition demonstrating the reliability of the presented setup for vapor-liquid equilibrium measurements.