A Triple-Port High-Pressure Volumetric Sorption Analyzer: Calibration, Measurements, and Uncertainty Analysis for Refrigerant Blend Separation Applications

A triple-port automatic high-pressure volumetric sorption
analyzer
was set up for sorption measurements over the temperature range of
(273.15–368.15) K and pressures up to 10 MPa. The main function
of this apparatus is to rapidly screen porous materials for the separation
of a specific gas mixture by measuring adsorption isotherms. Measurements
with empty sample containers were carried out to evaluate potential
systematic errors. Validation measurements on commonly studied cases
(CO2 adsorption on Zeolite 4A, ZIF-8, and Zeolite 13X)
were performed, and the excellent agreement with results of literature
indicates the high reliability of the measurement system. A comprehensive
uncertainty analysis was carried out to determine the uncertainty
of measurement results and to propose future improvements of the system.
Later, the measurement system was applied to screen suitable materials
for the separation of refrigerant blends, which are composed of six
pure refrigerants (R-32, R-125, R-1234yf, R-134a, R-1234ze(E), and
R-290). The studied porous materials include six metal–organic
framework samples, five zeolite samples, and one activated carbon
sample. The results show that all zeolite samples investigated (Köstrolith
3AK, 3ABFK, 3ABFK(HSD), 4AK, and 4ABFK) exhibit a higher adsorption
capacity for R-32 than for the other five refrigerants, with Köstrolith
4ABFK showing the highest selectivity. This makes it possible to use
any of these zeolite samples to separate R-32 from the R-410A blend
(a mixture of R-32 + R-125, to be phased down in the European Union)
or even separate R-32 from the mixtures composed of any of these six
refrigerants. The other studied porous samples do not yield any promising
results for the refrigerant blend separation.