Standard Test Method for Determination of Relative X-ray Diffraction Intensities of Faujasite-Type Zeolite-Containing Materials

Importancia y uso:

4.1 Zeolites Y and X, particularly for catalyst and adsorbent applications, are a major article of manufacture and commerce. Catalysts and adsorbents comprising these zeolites in various forms plus binder and other components have likewise become important. Y-based catalysts are used for fluid catalytic cracking (FCC) and hydrocracking of petroleum, while X-based adsorbents are used for desiccation, sulfur compound removal, and air separation.

4.2 This X-ray procedure is designed to monitor these Y and X zeolites and catalysts and adsorbents, providing a number more or less closely related to percent zeolite in the sample. This number has proven useful in technology, research, and specifications.

4.3 Drastic changes in intensity of individual peaks in the XRD patterns of Y and X can result from changes of distribution of electron density within the unit cell of the zeolite. The electron density distribution is dependent upon the extent of filling of pores in the zeolite with guest molecules, and on the nature of the guest molecules. In this XRD method, the guest molecule H₂O completely fills the pores. Intensity changes may also result if some or all of the cations in Y and X are exchanged by other cations.

4.3.1 Because of the factors mentioned in 4.3 that could vary the intensities of the XRD peaks, this XRD method will provide the best determination of relative crystallinity when the reference and sample have a similar history of preparation and composition.

4.4 Corrections are possible that can make this XRD method accurate for measuring percent zeolite in many specific situations. These corrections are well known to those skilled in X-ray diffraction. It is not practical to specify those corrections here.

Subcomité:

D32.05

Referida por:

D4365-19, D5758-01R21, D5357-19, D4365-19

Volúmen:

05.06

Número ICS:

71.060.01 (Inorganic chemicals in general)

Palabras clave:

catalyst; faujasite; X-ray diffraction; zeolite;