Dual-Modulated Polyamide Membranes Based on Vapor–Liquid Interfacial Polymerization for CO2 Separation

Polyamide (PA) membranes show great application potential in the CO2 separation study. However, the PA membranes prepared by the traditional interfacial polymerization (IP) have a dense microstructure and a singularity of functional groups, making it difficult to exhibit both high CO2 permeance and selectivity. Herein, we report a new dual-modulation strategy by preparation method optimization and filler modification to improve the CO2 separation performance of the PA membranes. The PA membranes prepared by vapor–liquid IP have a loose microstructure, which greatly improves the gas permeance. The introduction of mono-(6-ethanediamine-6-deoxy)-beta-cyclodextrin (CD) can better loosen the PA microstructure, and the CO2-philic groups in the CD boost the CO2 selectivity by the facilitated transport effect. Ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate is further sealed into PA membranes to remedy the possible microvoids or defects and CD cavities of the membrane microstructure. The prepared membranes display excellent CO2 separation performance with CO2/H2, CO2/CH4, and CO2/N2 selectivity of 8.2, 45.5, and 116.9, as well as a CO2 permeance of about 320 GPU. The proposed strategy provides a facile and effective route to dual-modulated PA membranes for the study of CO2 separation and can be expanded to other macrocyclic molecules and ionic liquid systems.