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

Abstract

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 CO2/CH4 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 CO2 reaction sites increased, which improved the reaction selectivity of CO2. In addition, the presence of amine groups on the inner and outer surfaces of the polymer nanotubes provided various transfer channels for CO2, which were conducive for CO2 gas transfer in the membrane. When the CC-PEINT content was 8 wt%, the CO2 permeability was 710 Barrer and CO2/CH4 selectivity was 60. The CO2 permeability and CO2/CH4 selectivity of the Pebax/CC-PEINTs membranes increased by 163% and 132%, respectively, compared with those of the pure Pebax membrane.