The Need

Amine solvent systems for post‑combustion capture remain costly and energy‑intensive, typically increasing the cost of electricity 70–80% and imposing a 25–40% energy penalty when retrofitted to coal plants. Membrane alternatives often lack the combination of very high CO₂ flux, high CO₂/N₂ selectivity, water tolerance at 57–77 °C, and module‑scale stability in realistic flue gases containing O₂, SOx, and NOx. Industry needs scalable elements compatible with vacuum operation and humid streams to reduce capture costs and simplify plant integration.

The Technology

OSU engineers have developed a thin selective‑layer, polyguanidine‑containing facilitated‑transport membrane coated on a highly permeable support. Polyguanidine serves as fixed‑site carriers that reversibly bind CO₂; optional co‑polymers and mobile carriers further assist CO₂ transport. The selective layer can be reinforced (e.g., graphene oxide) for rigidity under feed compression and permeate vacuum, and it operates effectively in warm, humid flue gas. Spiral‑wound modules have been fabricated and tested, delivering high flux and selectivity without solvent regeneration.

Commercial Applications

• Post‑combustion CO₂ capture from coal and NGCC flue gas.
• CO₂/H₂ separation for blue hydrogen and syngas conditioning.
• Biogas upgrading and CO₂ removal from cement/steel off‑gases.
• Acid‑gas selective separations (e.g., CO₂/H₂S) in natural‑gas processing.

Benefits/Advantages

• ~4,200 GPU CO₂ permeance with ~165–171 CO₂/N₂ selectivity.
• Stable for ~2,000 h on simulated and 100 h on actual coal flue gas.
• A two‑stage bench skid achieved 91% capture at >95% CO₂ purity.
• Operates with humid feeds, tolerates low‑ppm SO₂/NOx, and scales to 8‑inch spiral‑wound elements.