(698c) Real Adsorbed Solution Theory Model for the Adsorption of CO2 from Humid Gas on Calf-20

CALF-20 is a metal organic framework which acts as a physical adsorbent for CO₂. A potential benefit of CALF-20 over more traditional zeolite physical adsorbents is that CALF-20 exhibits a strong Type I adsorption behavior for CO₂, while H₂O exhibits S shaped Type V adsorption. As a result, CALF-20 maintains most of its CO₂ capacity for up to 50% relative humidity. Modeling and predicting the multi-component adsorption of H₂O and CO₂ on CALF-20 is a prerequisite for accurate process modeling. In this work a real adsorbed solution theory (RAST) model is developed to predict the non-ideal multi-component adsorption in H₂O – CO₂ – N₂ gas mixtures. We demonstrate that RAST can accurately represent the non-ideal adsorption behavior of H₂O – CO₂ and CO₂ – N₂ binary systems. The RAST model is then applied to predict the adsorption from ternary mixtures of H₂O, N₂, and CO₂. It is shown that co-adsorption of H₂O has a more negative effect on CO₂ adsorption at lower partial pressures of CO₂. This fact has significant implications on adsorption process design for low pressure flue gas sources such as coal boiler and natural gas combined cycle flue gas.