title: Adsorption and separation of CO2 on KFI zeolites: effect of cation type and Si/Al ratio on equilibrium and kinetic properties.
abstract: 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).
authors.affiliation: Department of Chemical Engineering, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Remy
authors.forename: Sunil A
authors.initials: SA
authors.lastname: Peter
authors.forename: Leen
authors.initials: L
authors.lastname: Van Tendeloo
authors.forename: Stijn
authors.initials: S
authors.lastname: Van der Perre
authors.forename: Yannick
authors.initials: Y
authors.lastname: Lorgouilloux
authors.forename: Christine E A
authors.initials: CE
authors.lastname: Kirschhock
authors.forename: Johan A
authors.initials: JA
authors.lastname: Martens
authors.forename: Yanliang
authors.initials: Y
authors.lastname: Xiong
authors.forename: Gino V
authors.initials: GV
authors.lastname: Baron
authors.forename: Joeri F M
authors.initials: JF
authors.lastname: Denayer