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

The ESCA spectra of a series of NiO/SiO₂ and NiO—Al₂ O₃/SiO₂ 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 Al₂O₃ has a great influence on the surface structure (formation of alumosilicate).