Formation of high-performance 6FDA-2,6-DAT asymmetric composite hollow fiber membranes for CO₂/CH₄ separation

We report that 6FDA-2,6-DAT polyimide can be used to fabricate hollow fiber membranes with excellent performances for CO₂/CH₄ separation. In order to simplify the hollow fiber fabrication process and verify the feasibility of 6FDA-2,6-DAT hollow fiber membranes for CO₂/CH₄ separation, a new one-polymer and one-solvent spinning system (6FDA-2,6-DAT/N-methyl-pyrrolidone (NMP)) with much simpler processing conditions has been developed and the separation performance of newly developed 6FDA-2,6-DAT hollow fiber membranes has been further studied under the pure and mixed gas systems. Experimental results reveal that 6FDA-2,6-DAT asymmetric composite hollow fiber membranes have a strong tendency to be plasticized by CO₂ and suffer severely physical aging with an initial CO₂ permeance of 300GPU drifting to 76GPU at the steady state. However, the 6FDA-2,6-DAT asymmetric composite hollow fibers still present impressive ultimate stabilized performance with a CO₂/CH₄ selectivity of 40 and a CO₂ permeance of 59GPU under mixed gas tests. These results manifest that 6FDA-2,6-DAT polyimide is one of promising membrane material candidates for CO₂/CH₄ separation application.