Dual-Layer Architecture in Hollow Fiber Membranes for Enhanced H2, CO2, and SF6 Separation

The growing demand for efficient hydrogen purification and the recovery of high-global-warming-potential gases has intensified the development of compact, energy-efficient membrane processes for industrial gas separation. Composite hollow fiber membranes (HFMs) provide an effective platform for integrating a multilayer structure of a porous substrate and a thin selective layer. However, the applicability of multilayer polymeric HFMs beyond conventional CO2 capture systems remains underexplored, particularly for gas pairs with different molecular sizes. In this study, a dual-layer PES/PDMS/PEBAX-1657 HFM comprising a PES substrate, an ultrathin PDMS gutter layer (∼85 nm), and a PEBAX-1657 selective layer (∼150 nm) was fabricated via sequential coating and investigated for the separation of H2, CO2, N2, and SF6. The performance of the membrane was evaluated using H2, CO2, N2, and SF6 as molecularly distinct probe gases over a pressure range of 1–5 bar. The PES/PDMS/PEBAX-1657 membrane exhibited H2, CO2, N2, and SF6 permeances of 140.82, 71.87, 25.02, and 16.56 GPU, respectively, at 30 °C and 5 bar. This work establishes the PES/PDMS/PEBAX-1657 HFMs as a versatile platform for fundamentally different gas-separation systems, rather than being introduced solely for CO2 capture/hydrogen purification. The combination of high gas permeance and a mechanically robust hollow fiber configuration offers potential for high-throughput operation with reduced membrane-area requirements, while selective-layer and interfacial engineering provide scope for further enhancement of separation selectivity. These findings establish the PES/PDMS/PEBAX-1657 structure as a promising multilayer HFM platform for hydrogen recovery and SF6 separation in electrical power industry applications.