Hydrothermal synthesis and structural characterization of zeolite-like structures based on gallium and aluminum germanates

Xianhui Bu, Pingyun Feng, Thurman E. Gier, Dongyuan Zhao, Galen D. Stucky

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157 Citations (Scopus)

Abstract

While extensive commercial success has been achieved through the use of organic molecules in the synthesis of aluminosilicate zeolites, the synthesis of the germanium-based zeolite structures using organic structure-directing agents is a largely unexplored area. Here we report a novel class of germanate zeolite structures prepared with inorganic cations or organic amines as structure-directing agents. These new materials possess five 4- connected 3-dimensional topologies with large (12-ring), medium (10-ring), small (8-ring), or ultrasmall (6-ring) pores. They have a variety of chemical compositions such as various Ge to Ga (or Al) ratios and exhibit interesting structural features such as helical chains and odd-membered rings. UCSB- 15GaGe and UCSB-15AlGe are the first germanate-based structures with 5- rings. UCSB-7 refers to a collection of isostructural, large-pore zeolite- like structures constructed by the cross-linking of helical ribbons. UCSB- 3GaGe is the only known T3+/T4+ (T refers to tetrahedral atoms) based zeolite structure with the net 38 topology. This structure is unusual because of its very high framework charge density unsurpassed by other amine-directed zeolite structures. GaGe-SOD2 and AlGe-SOD2 (sodalite analogues) have an unusually low framework symmetry for a sodalite structure. The cubic GaGe- SOD1 (or AlGe-SOD1) and the triclinic GaGe-SOD2 (or AlGe-SOD2) are ideal examples of the compositional and structural control of the inorganic framework by structure-directing amines. GaGe-ANA1 and GaGe-ANA2, two gallogermanate analcime analogues, are noncentrosymmetric, unlike many other analcime structures.

Original languageEnglish
Pages (from-to)13389-13397
Number of pages9
JournalJournal of the American Chemical Society
Volume120
Issue number51
DOIs
Publication statusPublished - 30 Dec 1998
Externally publishedYes

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