Optical spectroscopy of hydrated, dehydrated and ammoniated cobalt(II) exchanged zeolites X and Y

Abstract

In this paper we report the u.v. and i.r. spectra of hydrated and ammoniated X and Y zeolites with different Co^II loadings. The study includes adsorption and desorption of H₂O and NH₃. Hydrated Co^II zeolites contain mainly Co^II(H₂O)₆ in the supercage but with some interaction with the framework. Upon dehydration the Co^II ion can migrate into the small cavities and vary its coordination according to the dehydration temperature. Upon NH₃ adsorption, intermediates of the type Co(NH₃)_xO_l, O_l indicating lattice oxygen, can be identified, before the formation of the hexa-ammine Co²⁺ complex.