(589f) Measurement of and Challenges Associated with CO2-Water Equilibrium Measurements on Amine Based Adsorbents

Amine based adsorbents are often used for direct air capture because of their ability to selectively adsorb CO₂ in humid, low partial pressure conditions and undergo regeneration with steam. While these characteristics are advantageous from a process perspective, it creates challenges for measuring binary equilibrium isotherms. However, this data is still crucial for developing relevant isotherm models and building a process model. Furthermore, available binary equilibrium data in literature is limited and the best measurement method for these materials is unclear.

A gravimetric method proposed in literature for addressing the challenge described above is evaluated in this presentation.¹ The technique, which measures CO₂ equilibrium at various relative humidities, is applied to a commercial amine based adsorbent and the results compared to available literature data. The results are also compared to measured pure component CO₂ data to determine if the water enhancement effect cited in literature for amine based adsorbents is present.¹ Finally, several other Climeworks developed adsorbents are measured using the method to assess their ability to increase process performance relative to the commercial adsorbent.

References:

1) Young, John, et al. "The impact of binary water–CO 2 isotherm models on the optimal performance of sorbent-based direct air capture processes." Energy & Environmental Science 14.10 (2021): 5377-5394.