Chemical Composition of Silicate Zeolites

The vast majority of the 179 zeolite FTCs have silica-based representatives (131 codes, excluding silicoaluminophosphates). This number is to 

The variability in chemical composition of silicate zeolites is just amazing. Considering first just the framework, the number of heteroatoms i.e. atoms other than Si that can occupy tetrahedral positions in the framework) that have been (or have been claimed to be) incorporated into zeolites is formidable Al, Ga, Fe, Fe , Co , Be,  

Chemical variability in zeolites may also be related to the extraframework open space. The definition given above for zeolites implies a stoichiometry AB2 for the framework, which is constructed by corner sharing of AB4 tetrahedra. However, depending on the oxidation state of A and B, the framework may be electrically charged. For silicate 

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