Effect of water vapor from power station flue gas on CO₂ capture by vacuum swing adsorption with activated carbon

Due to the high absolute humidity of real flue gas, activated carbon, a hydrophobic adsorbent, was used to selectively adsorb CO₂ by vacuum swing adsorption in this study. The objective of this work is to study the feasibility and advantage of CO₂ capture along with simultaneous moisture removal by activated carbon and the effect of H₂O on CO₂ capture from wet flue gas streams. Through experiment and analysis, the “S” shape isotherms of water indicated water was easier to be desorbed from activated carbon. Then a cone shape model was proposed to depict water distribution inside the adsorption bed. As a consequence, water vapor hardly influenced the CO₂ capture performance. Moreover, the process can be operated under a relatively high vacuum pressure and short evacuation time. The preliminary results showed that our one-bed VSA process could yield a good CO₂ recovery of over 80% and a reasonable purity of 43%.