Carrier-driving CO2 separation by amine-rich membranes with intercalated graphene oxide

Amine-rich facilitated transport membranes (FTMs) attract great interest in intensifying the membrane-based CO₂ separation processes. The high-molecular-weight polyvinylamine (PVAm) polymers containing fixed-site carriers of the amino groups were used to prepare highly CO₂-permeable membranes. The sterically hindered PVAm polymers of poly(N-methyl-N-vinylamine) and poly(N-isopropyl-N-vinylamine) were obtained by functionalization of PVAm to provide superior CO₂ solubility. By loading the mobile carriers of amino acid salt (AAS) and CO₂-philic graphene oxide (GO), the prepared FTMs render enhanced CO₂ permeance and CO₂/N₂ selectivity. The d-spacing of 8.8 Å and the ultramicropores of 3.5 Å from GO nanosheets provide the combination of both selective surface flow and molecular sieving mechanisms to achieve improved CO₂ permeance and CO₂/N₂ selectivity. In addition, the intercalation of GO hinders N₂ transport through the membrane due to a longer pathway, while the mobile carriers of AAS introduced into the PVAm matrix facilitate CO₂ transport through the selective layer. Therefore, the CO₂/N₂ selectivity of the prepared FTMs was significantly enhanced to 171 based on the intensified carrier-driving transport mechanism. It can be concluded that amine-rich membranes based on both fixed and mobile carriers of the amino groups together with intercalated GO can synergistically improve the CO₂/N₂ separation performance, and be potentially applied for CO₂ capture from flue gas.