Abstract:
Infra-red spectroscopy of carbon dioxide adsorbed on Na-Ca(Mg)-Y faujasites is used to determine
the distribution of Ca and Mg ions over the cation sites. Physisorption of CO2 provides a sensitive
method for the detection of Ca2+ and Mg2+ in supercage positions. High temperature outgassing
of the samples facilitates the migration of bivalent ions from positions in the supercage to the small
cavities. Bivalent ions in the dehydrated Y samples are only present in the supercages when the
degree of ion exchange is 46 to 48 % or higher. For high temperature chemisorption of CO2,
the chemisorbed species are closely related to co-ordinated carbonate ions. The concentration of
this species does not exceed 2 molecules per unit cell.
