Theoretical study of transition metal cation exchanged zeolites: Interaction with NO

The accessibility of cation sites inside the sodalite cages of Y zeolite (SI′ sites) for adsorbate molecules (NO) is assessed by the cluster method, using hybrid functional (B3LYP) and by the ONIOM method, where B3LYP is used for the model system and the semiempirical PM6 method is applied to the real system. The stability of the adsorption complex at different cation sites is examined also by periodic DFT. Cu+ cations at SI′ sites form adsorption complexes of comparable stability to those at the SII sites in the supercage.