Flexibility of the Zeolite RHO Framework.InSituX-ray and Neutron Powder Structural Characterization of Cation-Exchanged BePO and BeAsO RHO Analogs

Autor:	David R. Corbin, Galen D. Stucky, Glover A. Jones, Laurine G. Galya, Tina Maria Nenoff, John B. Parise
Rok vydání:	1996
Předmět:	Bond length Crystallography Molecular geometry Aluminosilicate Chemistry General Engineering Molecule Thermal stability Physical and Theoretical Chemistry Molecular sieve Zeolite Catalysis
Zdroj:	The Journal of Physical Chemistry. 100:14256-14264
ISSN:	1541-5740 0022-3654
DOI:	10.1021/jp9604296
Popis:	This is an extensive study of the non-aluminosilicate analogs of the zeolite RHO. This molecular sieve is of great interest commercially because of its catalytic properties. In the absence of rigid supporting structural subunits (smaller cages or channels), the aluminosilicate RHO exhibits atypical framework flexibility with large displacive rearrangements. The beryllophosphate and berylloarsenate analogs are easily synthesized under very mild reaction conditions and therefore may be of interest for inexpensive and rapid commercial production. However, they have decreased thermal stability. In an effort to increase thermal stability and explore framework flexibility, we have synthesized and characterized a series of analogs of the non-aluminosilicate RHO framework. All materials crystallize in the space group I23, ranging from a = 13.584(2) A for Li-BePO RHO to a = 14.224(4) A for Ba-RbBeAsO RHO for hydrated phases. The extra framework cations are distributed over the double 8-ring, single 8-ring, and two...
Databáze:	OpenAIRE
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