Gas separation membranes developed through integration of polymer blending and dual-layer hollow fiber spinning process for hydrogen and natural gas enrichments

This article describes the research study on exploitation of polymer blending technology and dual-layer hollow fiber spinning process for the fabrication of a novel class of high performance gas separation membranes. The specific functional material employed for this purpose is a polymer blend constructed of the interpenetrated networks of PBI and Matrimid. It is within the scope of this study to unravel the effect of various key parameters on the microstructural evolution, transport properties and separation performance of the developed hollow fiber membranes. The resultant membranes possess desirable morphological and microstructural characteristics, particularly at the outer functional layer, and are free from any delamination at the interface. Analysis of the membranes suggests that both increase in the air-gap distance and application of elongational drawing have promoting effects on the membranes' permeance. Results also indicate that membranes with H₂/CO₂ selectivities as high as 11.11 (P_H2 = 29.26 GPU) can be obtained through spinning at sufficiently large air-gap distance. On the other hand, inducing the elongational drawing to the nascent fibers offers membranes with CO₂/CH₄ selectivities as high as 41.81 (P_{C O2} = 4.81 GPU). Therefore, either of these approaches can be employed for desirable tuning of the membrane's properties to suit the specific application. The variation in outer dope flow rate is identified as another effective technique amenable for tailoring the properties of the hollow fiber membranes. Other findings also show the effectiveness of chemical modification for further enhancing the H₂/CO₂ separation performance of the membranes. Membranes developed in this research study exhibit a very good resistance toward CO₂-induced plasticization and have viable potentials for various gas separation applications including hydrogen purification and natural gas separation.