Selectivity and Separation Factor for Components During Multicomponent Membrane Gas Separation
Seghman, Petr
Kratky, Lukas
Jirout, Tomas

How to Cite

Seghman P., Kratky L., Jirout T., 2022, Selectivity and Separation Factor for Components During Multicomponent Membrane Gas Separation, Chemical Engineering Transactions, 92, 109-114.


The membrane separation process offers a promising solution for syngas components separation and adjusting the ratio of the components. The multicomponent separation process is however complex and cannot be easily described. The presented study offers a comparison of ideal and real selectivities for three H2-CO-CO2 model mixtures containing 15-35 mol% H2, 35 mol% CO, and 30-50 mol% CO2. The mixtures were tested with total pressure drops 0.5-8 bar (retentate pressure from 2 to 10 bar with the permeate pressure levels of 1.2 bar, 2.5 bar, and 4 bar). The membrane module used in the study is a hollow fiber polyimide membrane module with 3000 hollow fibers with an inner diameter of 0.188 mm and a length of 290 mm with an active separation layer. The ideal selectivities for are a(H2/CO2) = 3.21 and a(CO2/CO) = 14.77. The experimental results show that with increasing stagecut, the selectivities drop to below 1.3 for H2/CO2 (40 % of the ideal selectivity) and to below 1.4 for CO2/CO (9.5 % of the ideal selectivity). Also, the selectivity decreases at a different rate for both different feed compositions and different permeate pressures. The H2/CO2 selectivity drops faster for lower permeate pressure, the CO2/CO selectivity drops faster for higher permeate pressure. The separation factors increase both for H2/CO2 and CO2/CO with increasing pressure differences. Also, with the lower permeate pressure (pP = 1.2 bar) both separation factors (for H2/CO2 and CO2/CO) increase at a greater rate.