Highly efficient of CO2/CH4 separation performance via the pebax membranes with multi-functional polymer nanotubes

Based on the one-dimensional tubular structure of halloysite nanotubes (HNTs), plant polyphenols and polyamines were used for in situ polymerization on the surface of HNTs to form amino-rich polymers, which were then removed as templates to synthesize polymer nanotubes. These nanotubes were then incorporated into a Pebax matrix to prepare mixed-matrix membranes (MMMs) for CO 2 /CH 4 gas separation. The removal of the HNT template increased the lumen diameter of the filler and significantly improved its gas permeability . And the amino groups on the inner surface of the polymer nanotubes were exposed. Further, the number of CO 2 reaction sites increased, which improved the reaction selectivity of CO 2 . In addition, the presence of amine groups on the inner and outer surfaces of the polymer nanotubes provided various transfer channels for CO 2 , which were conducive for CO 2 gas transfer in the membrane. When the CC-PEINT content was 8 wt%, the CO 2 permeability was 710 Barrer and CO 2 /CH 4 selectivity was 60. The CO 2 permeability and CO 2 /CH 4 selectivity of the Pebax/CC-PEINTs membranes increased by 163% and 132%, respectively, compared with those of the pure Pebax membrane.