Thin‐Film Composite Membranes by Stacking Polymeric Hollow Nanoparticles as a Selective Layer for <scp>H₂</scp>/<scp>CO₂</scp> Separation

ABSTRACT Polymeric membranes have been widely used in gas separation. However, the majority of these membranes do not meet the desired standards for separating H 2 and CO 2 . The reason behind their subpar performance lies in the contradicting effects that exist within polymers, namely the presence of favorable diffusion selectivity but unfavorable solubility selectivity for H 2 /CO 2 . A series of thin‐film composite (TFC) membranes were prepared via properly stacking the polymeric nanoparticles as selective layers and the rubbery Pebax as bonding and buffering layers. The chemical composition and structure of polymeric nanoparticles are analyzed by the FTIR. The pore size and structure of the selective layer formed by nanospheres are examined by the SEM, TEM, and XRD. The N 2 adsorption–desorption analysis of the PIM nanospheres/Pebax selective layer is performed. The morphology of the TFC membrane is also investigated. The gas permeation–separation performance of the TFC membranes, which were prepared at different temperatures and different thicknesses, varies greatly. It indicates that the gas permeation–separation performance of the PIM nanospheres/Pebax selective layer in TFC membranes gradually change from being dominated by smaller‐sized intrinsic pores in Pebax matrix to being dominated by larger‐sized extrinsic pores formed by PIM nanospheres stacking as the nanospheres content increasing. The adsorption of CO 2 by PIM nanospheres and the Pebax matrix becomes an obstacle to CO 2 permeating in the extrinsic pores, and it improves the H 2 /CO 2 selectivity. It also indicates that the TFC membranes prepared at 10°C have more regular and compact arrangements of nanospheres. In single gas testing, the H 2 permeance reaches ~3336 GPU coupled with the H 2 /CO 2 selectivity of ~17.2. Under the testing of a 50:50 mixture of H 2 : CO 2 , the concentration of H 2 can reach over 80% while having a recovery rate of over 50%. Even at a high recovery rate of 90%, the concentration of H 2 still can reach 70%.