AES AND EELS STUDY OF ALUMINA MODEL CATALYST SUPPORTS

Stoichiometry of alumina surface can influence the catalytic propertie s of alumina supported catalysts, Different types of the (0001) alpha- 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 obs erved via an excitation of the Al surface plasmon and an increase of t he Al/O Auger intensity ratio, Heating of the alumina crystal under ai r gives well stoichiometric oxide surface. But gamma-alumina layer pre pared by thermal heating of aluminium under air exhibits a lack of oxy gen without formation of an Al rich surface film.