Covalent organic frameworks-incorporated thin film composite membranes prepared by interfacial polymerization for efficient CO2 separation

Thin film composite (TFC) membranes with nanofillers additives for CO 2 separation show promising applications in energy and environment-related fields. However, the poor compatibility between nanofillers and polymers in TFC membranes is the main problem. In this work, covalent organic frameworks (COFs, TpPa-1) with rich NH groups were incorporated into polyamide (PA) segment via in situ interfacial polymerization to prepare defect-free TFC membranes for CO 2 /N 2 separation. The formed covalent bonds between TpPa-1 and PA strengthen the interaction between nanofillers and polymers, thereby enhancing compatibility. Besides, the incorporated COFs disturb the rigid structure of the PA layer, and provide fast CO 2 transfer channels. The incorporated COFs also increase the content of effective carriers, which enhances the CO 2 facilitated transport. Consequently, in CO 2 /N 2 mixed gas separation test, the optimal TFC (TpPa 0.025 -PIP-TMC/mPSf) membrane exhibits high CO 2 permeance of 854 GPU and high CO 2 /N 2 selectivity of 148 at 0.15 MPa, CO 2 permeance of 456 GPU (gas permeation unit) and CO 2 /N 2 selectivity of 92 at 0.5 MPa. In addition, the TpPa 0.025 -PIP-TMC/mPSf membrane also achieves high permselectivty in CO 2 /CH 4 mixed gas separation test. Finally, the optimal TFC membrane showes good stability in the simulated flue gas test, revealing the application potential for CO 2 capture from flue gas.