The general principles of the X-ray photoelectron spectroscopy (XPS) is briefly reviewed. Some applications of the technique in the field of heterogeneous catalysis is described. In particular the chemical and morphological changes of catalysts upon exposure to different gaseous molecules and to different thermal treatments are reported. Examples will be given of the use of the XPS technique to obtain the dispersion of a supported catalysts which is not possible to obtain with other means such as chemisorption or X-ray diffraction techniques. To this aim, appropriate theoretical models of the particle-support distribution are needed. In the case of supported Pd/Pt bimetallic catalysts it is shown how the combination of Auger and photoelectron peaks, characterised by different kinetic energies, allows to get non destructive depth profile information. The XPS characterization of supported Pd-Ag catalysts is reported, emphasising the advantages of using XPS to investigate surface segregation processes. The surface behaviour of CoMo catalysts used for hydrodesulfurization reaction is investigated as function of different supports and also of pre-treatment and reaction conditions.
X-ray Spectroscopy for catalyst characterization
2003
Abstract
The general principles of the X-ray photoelectron spectroscopy (XPS) is briefly reviewed. Some applications of the technique in the field of heterogeneous catalysis is described. In particular the chemical and morphological changes of catalysts upon exposure to different gaseous molecules and to different thermal treatments are reported. Examples will be given of the use of the XPS technique to obtain the dispersion of a supported catalysts which is not possible to obtain with other means such as chemisorption or X-ray diffraction techniques. To this aim, appropriate theoretical models of the particle-support distribution are needed. In the case of supported Pd/Pt bimetallic catalysts it is shown how the combination of Auger and photoelectron peaks, characterised by different kinetic energies, allows to get non destructive depth profile information. The XPS characterization of supported Pd-Ag catalysts is reported, emphasising the advantages of using XPS to investigate surface segregation processes. The surface behaviour of CoMo catalysts used for hydrodesulfurization reaction is investigated as function of different supports and also of pre-treatment and reaction conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
