Mössbauer spectroscopy was used to study the chemical state of tin in a new type of Sn-Pt/Al2O3 catalysts. Controlled surface reaction of tin tetraethyl with hydrogen preadsorbed on platinum resulted in the exclusive formation of a Pt-SnEt3 surface complex, which decomposed in hydrogen at 773 K to PtxSn alloy (3 < x < 4). Contamination of the catalyst by air at room temperature resulted in partial oxidation of tin in the alloy to SnO2. Upon oxidation at 673 K tin segregated to SnO2. Both SnO2 and PtxSn alloy were detected in the rereduced catalyst. Anchoring SnCl2 onto lithiated Pt/Al2O3 and subsequent reduction of the catalyst in hydrogen did not result in the formation of tin-platinum alloy, indicating an exclusive tin-alumina interaction.
- Mössbauer spectroscopy
- catalyst characterization (Mössbauer spectroscopy).
- controlled surface reactions
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