Non-localized charge compensation in high-silica zeolites

Periodic DFT calculations show that stability of cationic gallium-oxo clusters in high-silica zeolites is mainly controlled by the favorable geometrical environment of the Ga~ ions, whereas the effect of the direct interaction of the extraframework cations with the charge-compensating framework anionic sites is less important. This leads to formation of stable charge-alternating structures when conventional charge compensation does not allow the favorable coordination environment. The concept of non-localized charge compensation can be generally applied to intrazeolitic cationic species in high-silica zeolites and is useful to develop new structural models for zeolite-based catalysts, for instance, for Cu- or Fe-containing zeolites.