Abstract: The ²⁹Si NMR behaviour of the framework in divalent metal ion exchanged X-type zeolites was investigated, and the effects of exchange level, dehydration and the type of exchange ions(e.g.Cd²⁺,Cu²⁺,Co²⁺,Mn²⁺,Pb²⁺)on the ²⁹SiMASNMR spectra were discussed. It was found that at the exchange level of about 85%, the zeolite remained in a special state which might be related to a special catalytic activity at this ion exchange level.

Key words: Framework, Ion exchange, Exchange level, Hydrated state, Dehydrated state, Site exchange motion