Composition and Structure of Zeolites

In the interior of these channels, which are characteristic of zeolites, are water molecules and mobile alkali metal ions, which can be exchanged with other cations. These compensate for the excess negative charge in the anionic framework resulting from the aluminum content. The interior of the pore system, with its atomic-scale dimensions, is the catalytically active surface of the zeolites. The inner pore structure depends on the composition, the zeolite type, and the cations. The general formula of zeolites is 

Industrial Catalysis A Practical Approach, Second Edition Jens Hagen Copyright 2006 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31144-0 

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