CO2Separation

CO2 separation is the process of isolating carbon dioxide from a gas mixture, usually as part of carbon capture, utilization, and storage (CCUS). It applies to flue gases from power and industrial plants, natural gas purification, and syngas processing. The aim is to produce a CO2-rich stream for storage or reuse and a CO2-poor product gas.

Common methods include chemical absorption (post-combustion), physical solvents (pre-combustion), membranes, solid adsorbents, and cryogenic or oxy-fuel techniques. Chemical absorption uses aqueous amines such as MEA or DEA to bind CO2 reversibly, regenerated by heat. Physical solvents such as Selexol or Rectisol operate at high pressures. Membranes separate based on CO2 permeability and selectivity. Adsorbents like zeolites, activated carbon, or metal-organic frameworks capture CO2 and are regenerated by pressure or temperature swings. Cryogenic and oxy-fuel approaches exploit low temperatures or CO2-rich gas streams to achieve separation.

Key performance metrics include CO2 purity and recovery, energy required for regeneration, and overall cost. Choice depends on feed composition and target purity. Amine systems face solvent degradation and corrosion; membranes and adsorbents balance selectivity, capacity, and stability. Research aims to reduce energy penalties, extend material life, and improve integration of capture with storage or utilization.

CO2 separation is central to CCUS, enabling emission reductions in power generation, cement and steel production, and natural gas processing, and supporting climate policy goals through the capture and storage of anthropogenic CO2.