Surface probing of synthetic faujasites by adsorption of carbon dioxide. Part 2.—Infra-red study of carbon dioxide adsorbed on × zeolites exchanged with mono- and bi-valent ions
Adsorption of carbon dioxide in X-type zeolites exchanged with alkali and alkaline earth metal cations reveals bands in the infra-red spectra due to CO2 in a “bent” configuration. The spectra are interpreted in terms of carboxylate and carbonate species. Lattice oxygens of the type O1 seem to be involved. The small number of these species fails to correlate with any structural site. When the amount Ca2+ ions in the samples is high enough to occupy sites in both the small and the supercages, new structural species are formed.