Multiscale investigation for CO₂ capture using membrane with AEEA: Significance of fluid flow and AEEA content to CO₂ permeance

Since it is energy efficient, CO₂ capture by a membrane is a promising technique for mitigating an increase in CO₂ in the atmosphere. This study considers a membrane containing 2-(2-aminoethylamino) ethanol (AEEA) because of its higher interaction performance than that of the other amines. It was assumed that the feed gas which is a mixture of CO₂/He flows in a rectangular channel, and the membrane is placed at the bottom of the channel. Diffusional mass transfer of CO₂ from feed gas flowing in the channel to the surface of the membrane was investigated. Incorporating the results for CO₂ interaction with AEEA by density functional theory (DFT) calculation, the presented model can describe the effects of fluid (CO₂/He mixed gas) flow over the surface of the membrane and the AEEA content of the membrane on the gas transmission rate, i.e. the CO₂ permeance. Theoretical results reveal that the CO₂ permeance increases as the mean flow velocity increases. The CO₂ permeance also depends on the AEEA content of the membrane, i.e. the CO₂ permeance increases with increased AEEA content. It was also found that predicted CO₂ permeance has a range from 10⁻⁸ to 10⁻⁷ m³(STP)m⁻²s⁻¹Pa⁻¹ which is much larger than those obtained in the experiments using the polyamidoamine (PAMAM) dendrimer/polymer hybrid membrane, i.e. 10⁻¹⁰ to 10⁻⁹ m³(STP)m⁻²s⁻¹Pa⁻¹, indicating that AEEA can capture CO₂ from the CO₂/He mixed gas much more efficiently than the other amines.