Concentration and Recovery of CO₂ from Flue Gas by Pressure Swing Adsorption

The feasibility of recovering CO₂ from flue gas to generate a high-purity product by pressure swing adsorption (PSA) is studied by simulation using a proven predictive PSA model. Two promising sorbents, activated carbon and carbon molecular sieve, are examined. A nonconventional PSA cycle is designed for this purpose. With activated carbon as the sorbent, CO₂ can be concentrated from 17% in the flue gas to a product of 99.997% (at a CO₂ recovery of 68.4% and at a reasonably high feed throughput). Despite the favorable kinetic selectivity for CO₂ in the carbon molecular sieve, separation results using this sorbent are not as good, because the kinetic selectivity (of CO₂/N₂) is not high enough and consequently the equilibrium selectivity dominates the separation.