(229f) Adsorption of Carbon Dioxide with Small Pore, Cage Containing Zeolites

Mitigation of the increasing concentration of CO₂ requires active removal of CO₂ from air using direct air capture (DAC).^[1] Physisorbents, in particular zeolites, are attractive because of the potential for high selectivity, fast kinetics and low energy requirements for recycling.^[2] Low-silica zeolites with the FAU (13X) and LTA (4A) framework topologies are among the most commonly used adsorbents in industrial gas adsorption and separations. However, their strong CO₂ binding energy via both physisorption and chemisorption as well as their hydrothermal stability can lead to difficulties with regeneration, and thus lead to low recyclability even under vacuum regenerating conditions.^[3]

Here, we report CO₂ adsorption in zeolites at low concentrations (ca. 400 ppm). We show that the CO₂ adsorption capacities from modified, small pore, cage containing zeolites can outperform 13X and 4A.

Methods

CHA-, AEI- and AFX-type zeolites were synthesized,^[4–6] LTA- and FAU-type zeolites are commercial samples. Modification of these zeolites will be described. CO₂ adsorption was measured at 30 ºC using breakthrough experiments with a gas flow of 400 ppm CO₂/400 ppm and Ar (internal standard) balanced by He (specialty gas from Airgas).

Implications

The results presented here suggest that small pore, cage containing zeolites have potential for CO₂ capture when modified appropriately.

References

[1] E. S. Sanz-Pérez et al., Chem. Rev. 2016, 116, 11840–11876.

[2] A. Kumar et al., Angew. Chem. Int. Ed. 2015, 54, 14372–14377.

[3] S. M. W. Wilson et al., Ind. Eng. Chem. Res. 2020, 59, 8783–8794.

[4] C. Paolucci et al., J. Am. Chem. Soc. 2016, 138, 6028–6048.

[5] M. Dusselier et al., Chem. Mater. 2015, 27, 2695–2702.

[6] S. I. Zones, Synthesis of SSZ-16 Zeolite Catalyst, 1993, US5194235A.