Abstract: The crystallization processes of SAPO-34 molecular sieves were studied by MAS and CP/MAS NMR methods.It is shown that the silicon atoms were incorporated into the framework by two manners.During the process of formation of the crystal core, the silicon, phosphorus and aluminum atoms were incorporated into the framework simultaneously.At the later stage of crystallization parts of silico atoms substitute phosphorus atoms and/or phosphorus and aluminum pairs to be continually incorporated into the framework.This introduces various silicon-aluminum structures of SAPO-34 molecular sieves.

Key words: MAS NMR, Molecular sieves, SAPO-34