Abstract: Hydrogen spillover and its effect on Pt/SnO, has been studied in comparison with carbon-monoxide. The catalyst used was prepared by impregnation. The experiments of H_2-O_2 cycle pulse titration and reaction of H-saturated Pt/SnO_2 with O_2 evidently illustrated that hydrogen adsorbed on Pt/SnO_2 can migrate from Pt to platinized SnO_2 freely even at room temperature. Studying the behaviour of unplatinized SnO_2 mixed with Pt/SnO_2, we have shown the occurence of second- ary hydrogen spillover, i.e. the spillover hydrogen can migrate from Pt/SnO2 particles to bare SnO_2 particles as well.
It is demonstrated that while the catalyst surface exerts actions on the adsorbed molecules activating them, the adsorbates make a re-action on the catalyst in turn. By the electrical conductance measurement and Mössbauer spectra, it is revealed that the hydrogen migrating to SnO_2 from Pt interacted with SnO_2. The electron of spillover hydrogen transfered to the conduction band of semiconductor SnO_2, Causing an increase in the electrical conductance of SnO_2, and resulting in partial reduction of Sn~(4+). At a little higher temperature, the concentration of low-valence tin was high enough to be detected by Mössbauer spectra.