Scalable Pebax hollow fiber membranes for CO2 removal from LNG-fired power plants: Interface engineering and process analysis

초록

Membrane-based separation offers an energy-efficient route for CO2 capture from natural gas combined cycle (NGCC) power plants, where flue gas streams exhibit low CO2 partial pressure and high O2 content. Herein, we report a scalable fabrication strategy for defect-minimized inner-selective Pebax hollow fiber membranes (HFMs). A hydrophilic PDMS–PEG gutter layer is introduced onto the lumen surface to improve interfacial compatibility, followed by controlled deposition of a Pebax–PPEGMEA selective layer. Optimization of coating parameters reveals that elevated temperature and balanced residence time effectively suppress pore penetration and enable uniform film confinement within the hollow fiber lumen. Rotation-assisted drying is more effective than solvent vapor-induced swelling for hollow fiber geometries by suppressing gravitational pooling and promoting uniform film leveling. The optimized membranes exhibit CO2/O2 and CO2/N2 selectivities of 14.0 and 32.6, respectively, with a CO2 permeance of 126 GPU at 35 °C. Single-gas, binary (CO2/O2), and ternary (CO2/O2/N2) permeation tests confirm preservation of the intrinsic CO2 affinity of the Pebax-based selective layer. Process simulations using Aspen Custom Modeler coupled with Aspen Plus indicate that a three-stage membrane cascade employing the developed HFMs achieves an optimal trade-off at 94% CO2 recovery and 81% purity under NGCC conditions. Techno-economic analysis suggests a minimum capture cost of 171 USD t−1 CO2, while environmental assessment highlights the dominant influence of electricity-related emissions, emphasizing the importance of low-carbon power supply and moderate purity targets. Overall, this study establishes geometry-dependent coating and drying principles and demonstrates a viable pathway toward scalable Pebax HFMs for low-concentration CO2 capture. Highlights •Scalable inner-selective Pebax hollow fiber membranes are fabricated.•Geometry-dependent coating and drying mechanisms are identified.•Stable CO2 separation is achieved under realistic NGCC flue gas conditions.•A three-stage cascade achieves ∼90% CO2 purity and recovery.•Integrated analyses demonstrate techno-economic and environmental viability.

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