Water vapor effects on CO₂ separation of amine‐containing facilitated transport membranes (AFTMs) module: mathematical modeling using tanks‐in‐series approach

Abstract

Amine-containing facilitated transport membranes (AFTMs) are emerging membranes and have great potential for CO 2 capture. AFTMs are particularly suitable for humid flue gases, as water vapor enhances the facilitated transportation of CO 2. However, there is a lack of mathematical models available to evaluate the impact of water vapor on CO 2 separation performance for large-scale membrane modules. Therefore, developing a mathematical model considering the water vapor effects is of great importance to guide the large-scale applications of AFTMs for CO 2 capture. In this study, a mathematical model using tanks-in-series approach for CO 2 capture through AFTMs is proposed. In this model, the tanks-in-series approach can reflect the variable (water vapor-dependent) gas permeance along the membrane module. Modeling results showed the necessity of considering the effect of water vapor content decline along the module. In addition, both increasing temperature and pressure primarily lead to a faster decline of relative humidity (RH) along the membrane module, resulting in an increase of CO 2 recovery but a decrease of CO 2 product purity. For a gas stream with relatively low water vapor content (<2% in this study), different H 2 O permeance has a minor effect on separation performance. Moreover, permeate gas with higher water vapor content as well as higher RH is considered more suitable for further treatment of second stage membrane separation. In conclusion,

Understanding the Effect of Water on CO2 Adsorption

“…Membrane CO 2 capture is beyond the scope of this contribution. Nonetheless, because membranes often contain actual CO 2 adsorbents, such as amines, ,, ionic liquids, , enzymes or mimic enzymes, , MOFs, − carbon, and zeolites, ,, the water benefits or drawbacks on CO 2 membrane separation will be briefly discussed, with particular emphasis on water-facilitated transport in polymeric membranes. ,,,− Comprehensive reviews on membrane CO 2 removal from large point sources are readily available elsewhere. ,− ,,,,, …”

“…Moreover, because CO 2 separation membranes often contain actual CO 2 adsorbents, such as amines and polyamines, ,, MOFs, − zeolites, ,, carbon, ionic liquids, , enzymes, and enzyme mimics, , they are bound to have similarities with adsorbents. Although progress in this area has been reported in several authoritative reviews, ,,− the effect of water on CO 2 transport and selectivity across membranes will be discussed succinctly.…”