Effect of Water on CO(2) Adsorption on CaNaY Zeolite: Formation of Ca(2+)(H(2)O)(CO(2)), Ca(2+)(H(2)O)(CO(2))(2) and Ca(2+)(H(2)O)(2)(CO(2)) Complexes

Efficient CO(2) capture materials must possess a high adsorption capacity, suitable CO(2) adsorption enthalpy and resistance to water vapor. We have recently reported that Ca(2+) cations exchanged in FAU zeolite can attach up to three CO(2) molecules. Here we report the effect of water on the adsorption of CO(2). Formation of Ca(2+)(H(2)O)(CO(2)), Ca(2+)(H(2)O)(CO(2))(2) and Ca(2+)(H(2)O)(2)(CO(2)) mixed ligand complexes were established. The Ca(2+)(H(2)O)(CO(2)) species are readily formed even at ambient temperature and are characterized by ν((12)CO(2)) and ν((13)CO(2)) infrared bands at 2358 and 2293 cm(−1), respectively. The Ca(2+)(H(2)O)(CO(2))(2) species are produced at low temperature and are identified by a ν((13)CO(2)) band at 2291 cm(−1). In the presence of large amounts of water, Ca(2+)(H(2)O)(2)(CO(2)) complexes were also evidenced by ν((12)CO(2)) and ν((13)CO(2)) bands at 2348 and 2283 cm(−1), respectively. The results demonstrate that, although it has a negative effect on CO(2) adsorption uptake, water in moderate amounts does not block CO(2) adsorption sites.