SURFACE-COMPOSITION AND ELECTRONIC-STRUCTURE OF ZEOLITES USING X-RAY PHOTOELECTRON-SPECTROSCOPY

Synthetic and mineral zeolites with well-characterized bulk and framew ork composition over a wide range of Si/Al atomic ratios have been cha racterized by ESCA for the determination of Si/Al composition of exter nal layers. These surface Si/Al values have been compared to the bulk and framework stoichiometric values determined by various techniques. As the change in Si/Al ratio affects the crystalline structure of zeol ites, such change is reflected in the binding energy shift of framewor k atoms.