Time-of-flight powder neutron diffraction studies of dehydrated synthetic gallosilicate zeolites X, XY, and Y

Journal Article · Thu Dec 18 04:00:00 EST 1986 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100284a030· OSTI ID:6946841

Newsam, J M; Jacobson, A J; Vaughan, D E.W.

The structures of dehydrated synthetic gallosilicate zeolites with the faujasite (FAU) framework, Na/sub x/Ga/sub x/Si/sub 192-x/O/sub 384/ with x = 85 (type X), x = 72 (XY), and x = 57 (Y), have been determined by full-profile analyses of time-of-flight powder neutron diffraction data. The structures are each described satisfactorily in space group Fd3m, indicating no long-range order of silicon and gallium. The cubic unit cell constants of the three zeolites are not collinear with x. In contrast, both the mean T-O bond length (T identical with tetrahedral species Si, Ga, or Al) and the mean T-O-T angle vary nearly linearly with x. Literature data for analogous aluminosilicate zeolites reveal similar trends which are related to variations with x in the /sup 29/Si chemical shifts. The observed sodium cation configurations are consistent for both the dehydrated aluminosilicate and gallosilicate zeolites. Each of the four sodium ion sites has an upper population limit, and the nonframework cation configuration thus evolves with composition in discontinuous stages. It is suggested that such changes in the cation arrangements are implicated in observed discontinuities in the variation with composition of certain macroscopic properties of FAU framework zeolites.

• Research Organization: Exxon Research and Engineering Co., Annandale, NJ
• OSTI ID: 6946841
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:26; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DATA
DIFFRACTION
EXPERIMENTAL DATA
GALLIUM COMPOUNDS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MINERALS
NEUTRON DIFFRACTION
NUMERICAL DATA
OXYGEN COMPOUNDS
POWDERS
SCATTERING
SILICATES
SILICON COMPOUNDS
SODIUM COMPOUNDS
SPACE GROUPS
TIME-OF-FLIGHT METHOD
ZEOLITES