Abstract:

 The structure of CuO-BaO/SiO2 catalysts and their reduced states has been characterized by means of XRD, XPS and EXAFS. Both the results of XRD and XPS indicate that(topper and barium in CuO-BaO/SiO2 exist in CuO and BaO respectively and the SiO2 support has influence on the structure of CuO. The EXAFS results show that the coordination number and length of Cu-O shell and Cu-Cu shell gradually decrease with the supported content decreasing and the extent of decrease is the largest for low supported content samples. When the supported content exceeds 13.39%, CuO in samples is in crystalline state, when the supported content is smaller or equals 13.39%, CuO in samples is in monolayer dispersion state. In the reduced catalyst samples, only metal copper is detected. With the content of CuO in CuO-BaO/SiO2 decreasing, the length and coordination number of Cu-Cu bond of metal copper on reduced catalyst surface also decrease gradually.

Key words: CuO, BaO, XRD, XPS, EXAFS, Ultrafine SiO2