Pressure-resistant polyimide hollow fiber membranes for high-performance helium recovery from natural gas

Industrial gas separation processes demand membranes with superior separation performance under high feed pressures. Herein, we fabricate defect-free hollow fiber membranes (HFMs) using 6FDA-mPDA0.9-TFMB0.1 copolyimide, achieving both exceptional pressure resistance and excellent gas separation performance. Through a dry-jet/wet-quench spinning approach, we systematically optimize the microstructure of the HFMs by adjusting the dope composition and spinning conditions. The results reveal that polymer concentration, dope-to-bore fluid ratio, and take-up rate have a significant impact on the pressure resistance of HFMs. Under optimized conditions, the fabricated HFMs exhibit a high burst pressure of 10.5 MPa, along with excellent gas separation performance, including a He permeance of 72.1 GPU and a He/CH4 selectivity of 178. Additionally, mixed-gas permeation experiments conducted at feed pressures up to 750 PSIA demonstrate excellent resistance to heavy hydrocarbons. These ultra-strong, high-performance HFMs show great potential for efficient helium separation from natural gas under high-pressure conditions.