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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 14, Number 5
BKCSDE 14(5)
May 20, 1993 

Encapsulation Characteristics of Gas Molecules in the Cavities of Zeolite A
Jin Hyun Kwon, Kee Heon Cho, Hae Won Kim, Soong Hyuck Suh, Nam Ho Heo*
Encapsulation capacities (Vgas) of, H2, N2, CO, CH4 and CO, for Cs2.5Na9.5-A (Cs-A) and Na12-A (Na-A) zeolites have been measured in order to understand the effect of molecular properties on the Vgas. With appropriate number of large blocking cations on the main windows of cavities in zeolite A, gas molecules can be encapsulated in both the α-and β-cages, resulting in much large Vgas. Vgas is proportional to the encapsulation pressure (Pe) and is also dependent on the molecular properties of encapsulated gases themselves, especially on intermolecular forces originated from the quadrupole moments of molecules in the molecular-dimensioned cavities of zeolite A. At the low range of Pe, molecules with larger Vgas and intermolecular forces apparently have smaller increasing tendencies of Vgas upon increases in Pe, showing a linear relationship between the tendencies and intermolecular forces rather than their sizes. Interactions between encapsulated molecules of CH4 and framework of Cs-A have been estimated and they seem to depend on the number of encapsulated molecules per unit cell. On the basis of calculated density of CO2, presence of liquid-like phase for the encapsulated molecules in the molecular dimensioned cavities of zeolite A is postulated.
583 - 588
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