(152k) Carbon Capture Demonstrated at ~1 Tonne CO2/Day Scale By an Integrated Membrane Skid

Large-scale application of membrane in decarbonizing flue gas has been limited by the insufficient CO₂/N₂ selectivity of most polymeric materials and the unproven thin membrane fabrication at scale. Aiming to overcome these limitations, a novel facilitated transport membrane (FTM) containing polyguanidine as fixed-site carrier was synthesized in a thin-film composite configuration. The FTM was also scaled up to 20" in width by a roll-to-roll process. A prototype spiral-wound (SW) membrane module was fabricated with a commercial-size diameter of 8" and a membrane area of 35 m². This SW module was tested with an actual coal flue gas at the Center for Applied Energy Research (CAER) at the University of Kentucky, which exhibited an average CO₂ permeance of 4269 GPU with a CO₂/N₂ selectivity of 165 and remained stable for 100 h.

An integrated membrane skid was then constructed, where 2 SW membrane modules were arranged to form an enriching cascade. The 8"-diameter prototype SW module previously tested at CAER was installed as the primary CO₂ capture stage, while a smaller SW module (5" diameter and 12 m² membrane area) was used to further enrich the CO₂ to >95% purity. By using a simulated coal flue gas (13% CO₂), the skid was operated at steady-state for 800 h with 91.0% of the CO₂ removed from the flue gas, delivering 1.33 tonne/day CO₂ product at 95.5% dry purity.

The bench skid was then installed at the National Carbon Capture Center (NCCC), Wilsonville, AL and tested with an actual natural gas (NG) flue gas (8.6% CO₂). 90–99% CO₂ capture degrees were demonstrated during the parametric testing, and the skid was operated at steady state for 500 h cumulatively with 91.0% CO₂ capture and >95% CO₂ purity. A simulated natural gas combined cycle (NGCC) flue gas (4.3% CO₂) slipstream was further provided by diluting the NG flue gas with air, and 90–99% CO₂ capture degrees were also achieved with dry CO₂ purities all above 95%.