Rv. Jasra et al., CORRELATION OF SORPTION BEHAVIOR OF NITROGEN, OXYGEN, AND ARGON WITH CATION LOCATIONS IN ZEOLITE-X, Industrial & engineering chemistry research, 35(11), 1996, pp. 4221-4229
Specific retention volume, sorption selectivity, and heat of sorption
for nitrogen, oxygen, and argon have been measured in zeolite X having
alkali or alkaline-earth metals as extra-framework cations using gas
chromatography. These sorption properties show a strong dependence on
the nature as well as the extent of extra-framework cation, reflecting
that the cations are the principle sites for interactions with the so
rbate molecule. Zeolites studied show sorption selectivity toward nitr
ogen from its mixture with oxygen or argon. The electrostatic interact
ions between sorbate molecules and the cations are largely responsible
for the observed nitrogen selectivity for the zeolite from its mixtur
e with oxygen or argon. The nonlinear dependence of the sorption prope
rties with cation charge density indicates that the interactions of th
e sorbate molecule depend not only on the cation type but also on the
sites it occupies in a zeolite structure. The correlation observed bet
ween sorption properties and the cation site occupancy shows that nitr
ogen can be used as a probe for determining cationic sites in a zeolit
e structure.