Investigation of the coordination state of aluminum in beta zeolites by X-ray photoelectron spectroscopy

beta zeolites have been characterized by X-ray photoelectron spectroscopy ( XPS). Owing to the small crystallite size (20 nm), nearly 90% of the Si and Al content can be estimated from the Si 2p and Al 2p peaks. The chemical s tate of Al was established by decomposition of the Al KLL Auger transition. Three types of Al could be differentiated: tetrahedral (Al-IV), octahedral (Al-VI), and tricoordinated (Al-III). From the decomposition of the Al KLL peak of a beta zeolite calcined to remove its template, it was found that Al-IV transforms to Al-III and Al-VI. Reversibility of Al-III to Al-IV also occurred when the sample was ammonium-exchanged, confirming Al-27 MAS NMR results.