Effect of Ge content on the synthesis and structure of Ge-ITQ-13 zeolite

A series of Ge-ITQ-13 zeolites with Si/Ge molar ratio from 10 to 40 were synthesized and characterized with XRD, IR, FE-SEM, and Si-29 MAS NMR techniques. The results verified that almost of all the Ge atoms in the synthesis gel was incorporated into the ITQ-13 framework. Ge plays a structure-directing role in the crystallization process as a result of facilitating formation of double four-membered ring structural units. As a consequence, ITQ-13 zeolites can be synthesized with the synthesis gel having a high content of H2O in the presence of Ge. Si-29 MAS NMR spectroscopy shows that the incorporated Ge atoms are not randomly distributed in the Ge-ITQ-13 framework but selectively occupy certain lattice sites.