Computational Evaluation of Carriers in Facilitated Transport Membranes for Post-Combustion Carbon Capture

Incorporating molecular amines as mobile carriers in facilitated transport membranes (FTMs) has been demonstrated to significantly enhance the CO₂ permeance and CO₂/N₂ selectivity of the membrane for CO₂ capture from flue gas. In this study, by employing computational techniques such as the density functional theory, molecular dynamics studies, and Monte Carlo simulations, the role of mobile carriers is systematically studied at the molecular level from the perspectives of the amine–CO₂ reaction chemistry, diffusivities of carriers and gases, and N₂ sorption. The water uptake of FTMs with and without mobile carriers is also experimentally quantified. The introduction of mobile carriers is shown to enhance the diffusivities of CO₂ reaction products and the water uptake compared to FTMs without mobile carriers. The choice of mobile carriers is also demonstrated to influence the separation performance. Computationally, certain carriers are shown to possess a faster reaction kinetics and a higher CO₂ loading capacity; these carriers also demonstrate a better CO₂ permeance experimentally. The good consistency between the computational and experimental observations validates the computational models employed and insights generated in this study. The outcomes of this work shed light on the future design and selection of carrier structures, and the adopted computational approaches can be employed to discover promising mobile carrier candidates.