Chemical effect on the XPS spectra of the valence band and on O KLL and Pd MNN Auger spectra in pumice‐supported catalysts

X‐ray photoelectron spectra of the valence band and X‐ray‐excited O KLL Auger transition of pumice‐supported Pd and Pt catalysts have been obtained and compared to the corresponding spectra of pumice (a naturally occurring amorphous aluminosilicate). The changes observed indicate interaction between metal and support. The valence region of the catalysts consists of three large peaks: one due to the d band of the metals and the other to the O 2p non‐bonding orbitals and bonding‐type orbitals formed by a mixing of the atomic orbitals (O 2p, Si 3s and Si 3p) of oxygen and silicon from the support. The intensity decrease of the component due to the bonding orbitals, observed in the catalyst spectra, suggests electron donation from the support to the metal. The O KLL valence Auger spectra of pumice and of catalysts have been analysed. The changes in the Auger pattern are attributed to variations of the atomic orbital composition of the valence levels due to the presence of the supported metals.