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Adsorption and Separation of CO2 on KFI Zeolites: Effect of Cation Type and Si/Al Ratio on Equilibrium and Kinetic Properties
- Remy, Tom, Peter, Sunil
A., Van Tendeloo, Leen, Van der Perre, Stijn, Lorgouilloux, Yannick, Kirschhock, Christine E. A., Baron, Gino V., Denayer, Joeri F. M.
- Langmuir 2013 v.29 no.16 pp. 4998-5012
- adsorption, aluminum, calcium, carbon dioxide, cations, chemical industry, lithium, magnesium, methane, nitrogen, silicon, sodium, strontium, zeolites
- Selective separation of CO₂ is becoming one of the key technologies in the (petro-) chemical industry. This study focuses on the adsorption and separation of CO₂ from CH₄ on a new low-silica (LS) type of the eight-membered ring KFI zeolite. A series of alkali (Li, Na, K) and alkaline-earth (Mg, Ca, Sr) exchanged samples of the new LS KFI were synthesized and characterized. LS Li-KFI showed the largest pore volume, whereas LS Na-KFI and LS K-KFI were inaccessible for Argon at 87 K. Adsorption of CO₂ at 303 K demonstrated the dominant quadrupolar interaction on alkali-exchanged LS KFI samples. LS Li-KFI showed the largest capacities upon high pressure isotherm measurements of CO₂ (4.8 mmol/g), CH₄ (2.6 mmol/g), and N₂ (2.2 mmol/g) up to 40 bar at 303 K. The performance of the new LS KFI was compared to a KFI sample (ZK-5) with a higher Si/Al ratio. Isotherm measurements and dynamic breakthrough experiments demonstrated that ZK-5 samples show larger working capacities for CO₂/CH₄ separations at low pressure. Li-ZK-5 and Na-ZK-5 show the highest capacities and high selectivities (similar to benchmark 13X).