Investigation of the Coordination State of Aluminum in β Zeolites by X-ray Photoelectron Spectroscopy

β 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 state 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 β 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 27 Al MAS NMR results.