Zeolite-encapsulated metal chelate

The application of zeolite encapsulated metal chelate complexes in catalysis is a promising area of research. In particular shape selective oxidations catalyzed by metallophthalocyanines (MPc), shown in Figure 1, included in synthetic faujasite (FAU) type zeolites (2-10) appear to be competitive with other molecular sieve based catalysts that may have commercial potential. The restricted apertures ( 7.4 A) to the supercages (12A) in FAU type zeolites precludes removal of the large MPc complex unless the zeolite lattice is destroyed. Such physically trapped complexes have been termed ship-in-a-bottle complexes as well as zeozymes (to reflect the biomimetic reactivity that is often associated with these catalysts). 

Nuetral templates may not be bound to the zeolite surface but simply trapped. This is the basis of our zeolite synthesis method for the preparation of ship-in-a-bottle metal complexes, ie crystallization of the zeolite around a metal chelate complex. Zeolite encapsulated metal complexes have many applications, ranging from shape selective catalysis [9] to magnetic resonance imaging contrast agents [10]. 

The crystallization of zeolites and molecular sieves with metal complexes represents a fresh strategy for the synthesis of these materials as well as a novel method for encapsulation of metal chelate complexes. We have shown that several first row tranistion metal phthalocyanines complexes can be encapsulated in X and A type zeolites by synthesizing the zeolite around the metal complex. Preliminary results indicate the concentration and type of phthalocyanine complex modify the crystallization of X type zeolites. The extension of this method to other metal chelate complexes and molecular sieves is currently under investigation. 

Zeolite-Encapsulated Carbonyl, Metal Chelate Complexes... 

Aluminosilicate molecular sieves with the FAU structure have been crystallized in the presence of several metallophthalocyanines. A percentage of the complexes becomes included into the zeolites. The synthesis of NaX around the metal chelate represents a new method for encapsulating such complexes and modifying zeolite molecular sieves. The entrapped complexes were characterized by XRD, IR and UV-VIS spectroscopy. Preliminary results suggest the metal complexes may function as templates by modifying the gel chemistry. 

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