• The Journal of Natural Sciences
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• v.8 no.1
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• pp.41-45
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• 1995

A. partially decationized Y zeolite was pretreated under specific conditions. It was found this calcinated zeolite retains its separation properties for mixtures of the gases hydrogen, nitrogen, oxygen, carbon monoxide, and methane but has much lower affinity for water molecules than untreated, e.g., zeolites A type or X type. The observed effect is discussed on the basis of the results of adsorption measurements on the adsorption capacities, isotherms, and heats of adsorption.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.14-24
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• 1987

The CNDO/2 method has been used to calculate the electronic structure of the zeolites and silicas, and to investigate the interaction of CO molecules with the OH groups or the exchanged cation in the zeolites. The interaction energies of CO molecules with OH groups in silica were ca. 12kcal/mol, the bond distance, R(O-H${\cdots}$C) was 2.6${\AA}$. The strength of bond between CO molecules and various types of cations in the zeolites was in the following order: $H^+ < Na^+ < Li^+$, i.e., this increased with increasing electrostatic field of cations. The bond orders of CO molecules interacting with the OH groups or the cations increased but for the OH-OC type interaction. The theoretical decationization energies of exchanged cations in the zeolites decreased in the order: $H^+ > Li^+ > Na^+$. And these energies depended on the amount of charge density transfered from the skeleton to the cations in order to compensate its negative charge.