(157c) New Facilitated Transport Membranes for CO2 Capture from Flue Gases

Large-scale application of membrane for CO₂ capture from flue gas has been limited by the insufficient CO₂/N₂ selectivity of most polymeric materials as well as the unproven thin membrane fabrication at scale. Aiming to overcome these limitations, we have synthesized new facilitated transport membranes (FTMs) in a thin-film composite configuration with 170-nm selective layer coated on a nanoporous support. The FTM was also scaled up to 21 inches in width by a roll-to-roll process. Using the scale-up FTM, prototype spiral-wound (SW) membrane modules were fabricated, each with 41 membrane leaves, resulting in a commercial-size diameter of 8 inches and an effective membrane area of 35 m². The SW module was tested with actual coal flue gas, exhibiting a CO₂ permeance of 4269 GPU with a CO₂/N₂ selectivity of 165 and remained stable for 100 h in the presence of 12% O₂ and ppm levels of SO₂ and NO_x. Then, we designed and constructed an integrated 2-stage membrane skid, where the 8"-diameter prototype SW module was installed as the primary CO₂ capture stage, while a smaller SW module (14 membrane leaves, 5" in diameter, and 12 m² membrane area) was used to further enrich the permeate of the first stage to >95% CO₂ purity. This presentation will discuss skid tests using simulated coal and natural gas (NG) flue gases containing 15% O₂, 3 ppm SO₂ and 3 ppm NO₂, and actual NG flue gases with 3 ppm NO₂ at the National Carbon Capture Center. 90 – 99% CO₂ capture degrees were demonstrated with dry CO₂ purities all above 95% at 1 – 4 tonne of CO₂/day. Also demonstrated were membrane module and process stabilities with simulated flue gases for 1,200 h and actual NG flue gases for 800 h. The extensive tests and field validations of the membrane material, module, and process shed a light on the commercialization potential of the membrane technology.