Pure Polymorph C of Zeolite Beta Synthesized by Using Framework Isomorphous Substitution as a Structure-Directing Mechanism.

Subsitution of germanium for silicon in the preparation of the zeolite Beta allows the synthesis and characterization of a third, heretofore predicted, polymorph "C"; a [001] view is shown in the picture. Germanium preferentially occupies positions in double four-membered ring cages, the secondary building units of polymorph C, and favors the formation of polymorph C regardless of which of the eight organic structure-directing agents were used.