Carbon molecular sieve hollow fiber composite membrane derived from PMDA-ODA polyimide for gas separation

Abstract

Carbon molecular sieve (CMS) membranes have excellent gas separation property over conventional polymeric membranes and superior anti-swelling property. PMDA-ODA polyimide has high thermal stability and good mechanical property. It has been extensively adopted as the precursor of CMS membrane. However, due to the insoluble nature, PMDA-ODA CMS membranes are limited to configurations like dense symmetric films or composite membranes using porous inorganic or metal substrates. In this work, CMS hollow fiber composite membranes based on an asymmetric PMDA-ODA hollow fiber were successfully prepared for the first time. The neat PMDA-ODA hollow fiber membrane was crosslinked by polyethyleneimine to alleviate pore collapsing during carbonization and then dip-coated by a PMDA-ODA PAA solution to seal the surface defects. The PDMA-ODA CMS composite hollow fiber membranes showed gas permeances of 93.4 GPU, 19.6 GPU, 6.5 GPU, and 4.7 GPU for CO₂, O₂, N₂, and CH₄, respectively, with an ideal selectivity of 14.4, 3.0, and 19.8 for CO₂/N₂, O₂/N₂, and CO₂/CH₄ gas pairs, respectively. The attractive gas separation property shows a great potential for industrial application.