In-situ X-ray photoelectron spectroscopy study of supported gallium oxide

In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO2, γ-Al2O3, TiO2, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.