AES and EELS study of alumina model catalyst supports

Stoichiometry of alumina surface can influence the catalytic properties of alumina supported catalysts. Different types of the 0001.a-alumina surface were prepared by thermal treatment under atmosphere or vacuum and by ion sputtering. Heating under vacuum and ion sputtering lead to the formation of an aluminium rich surface layer. This is observed via an excitation of the Al surface plasmon and an increase of the AlrO Auger intensity ratio. Heating of the alumina crystal under air gives well stoichiometric oxide surface. But g-alumina layer prepared by thermal heating of aluminium under air exhibits a lack of oxygen without formation of an Al rich surface film.