engleski

Zeolite Nucleation – Fictions and Fact

Because of the great influence of zeolita crystal size on the mode and efficiency of their applications, the knowledge on the nucleation of zeolites has a crucial importance in the designing of the products having desired particulate properties needed for specific applications. For this reason, the existing concepts of zeolite nucleation are overviewed and critically evaluated. On the basis of the evaluation it is concluded that: (a) “ classical” homogeneous and heterogeneous nucleation in the liquid phase are neglected as the processes of the formation of zeolite nuclei, (b) secondary nucleation can occur only on the seed crystals, under specific synthesis conditions, (c) formation of nuclei in the gel matric is relevant for heterogeneous (untemplated or templated aluminosilicate hydrogels) and homogeneous (untemplated or templated, initially clear aluminosilicate solutions) systems and (d) the general principles of zeolite nucleation do not depend on the system (homogeneous, heterogeneous, templated, untemplated), chemical composition of the reaction mixture, crystallization conditions and the type of crystallized zeolite.

homogeneous nucleation; heterogeneous nucleation; autocatalytic nucleation; nuclei crystallization

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