Polyacrylonitrile hollow fiber membranes for efficient CO₂/N₂ separation from flue gas: Fabrication and process optimization

The increasing industrialization and fossil fuel consumption have led to a rise in CO₂ emissions, necessitating the development of efficient carbon capture technologies. Among various approaches, membrane-based gas separation stands out for its energy efficiency, scalability, and operational simplicity. In this work, polyacrylonitrile (PAN)-based hollow fiber membranes (HFMs) were fabricated through a scalable process by systematically varying key spinning parameters such as bore and dope flow rates. The resulting HFMs exhibited asymmetric morphology, confirmed through structural characterization. Further, physicochemical analyses confirmed the functional property and thermal stability of the PAN HFMs. Different HFMs were evaluated for their pure CO₂ permeance and ideal CO₂/N₂ selectivity, and the HFMs prepared with a 2:3 bore-to-dope flow rate ratio showed better performance among various HFMs. The results indicated optimal CO₂ separation performance, achieving an ideal CO₂/N₂ selectivity of 4.3 with a pure CO₂ permeance of 266.2 GPU and a mixed CO₂/N₂ selectivity of 12.3 with a CO₂ permeance of 168.1 GPU under mixed gas feed conditions. Thereafter, this optimal HFM was subjected to pressure variation (1–5 Bar g ) experiments under both pure and mixed gas feed (15/85 vol% CO₂/N₂) conditions at room temperature. These HFMs maintained stable CO₂ separation performance in the long-term permeation study with a mixed-gas feed, indicating good resistance to CO₂-induced plasticization and confirming their long-term operational stability. Overall, this study demonstrates the potential of an optimized PAN HFM for industrial CO₂ separation applications from flue gases.