The influence of treatment conditions on Pt/SnO 2 properties and its catalytic activity in CO oxidation was investigated. It was found that the temperature and atmosphere of catalyst heating had a great impact on the active phase dispersion, the chemical composition of the surface layer and the O 2 adsorption capacity of the Pt/SnO 2 catalysts. TOF-SIMS analysis and XRD measurements showed that the heat treatment in an atmosphere of H 2 promotes the formation of bimetallic compounds of Pt-Sn and different species such as PtOH, PtO 2 , PtO 2 H, PtOCl, PtSnO, PtSnOH. It was stated that their presence significantly affects the activity of the catalyst in the CO oxidation. The catalyst capacity of O 2 adsorption varied depending on the treatment conditions. The catalyst treated at 600°C in oxygen showed the greatest ability of oxygen adsorption. A significant difference in the activities between the catalyst samples heated in O 2 or H 2 atmosphere was found. The highest activity was obtained for 1%Pt/SnO 2 sample treated in oxygen at 700°C. The treatment in hydrogen above 100°C caused a decrease in the catalyst activity.

The concept of very strong metal–support interactions (VSMSI) was defined in regard to the interactions that influence the catalytic properties of catalysts due to the creation of a new phase as a result of a solid-state chemical reaction between the metal and support. In this context, the high catalytic activity of the 1%Pt/Al2O3 catalyst in the CO oxidation reaction at room temperature was explained. The catalyst samples were reduced at different temperatures ranging from 500 °C to 800 °C and characterized using TPR, O2/H2 titration, CO chemisorption, TPD-CO, FTIR-CO, XRD, and TOF-SIMS methods. Based on the obtained results, it was claimed that with very high temperature reduction (800 °C), nonstoichiometric platinum species [Pt(Cl)Ox] strongly anchored to Al2O3 surface are formed. These species act as the oxygen adsorption sites.