Joachim Finster

Esca investigations of some NiO/SiO2 and NiO—Al2 O3 /SiO2 catalysts

Abstract The ESCA spectra of a series of NiO/SiO 2 and NiO—Al 2 O 3 /SiO 2 catalysts are reported, together with those of some reference compounds. The positions and shapes of the lines, in conjunction with a quantitative surface analysis from relative intensities, allow the identification of different surface phases, e.g. an NiO-like phase in the impregnated catalysts with very low catalytic activity and an Ni talc-like phase in the precipitated catalysts which have higher activity. The addition of Al 2 O 3 has a great influence on the surface structure (formation of alumosilicate).

Photoelectron intensity spectroscopy analytical and structural information from peis applied to zeolites

Abstract X-ray photoelectron spectroscopy (XPS or ESCA) based on calculated photoionization cross sections was used to investigate the surface Si/Al ratio of different zeolites and the cation distribution in Ag- and Ca-exchanged NaA-zeolites. We find the same module at the surface as in the bulk, but a strong de-alumination of the surface after HCl treatment. The Ag + ions are enriched and the Na + ions depleted in the outer cavities of the zeolite crystals, both in strong dependence on the Ca content.