Preferential CO oxidation in hydrogen (PROX) on unsupported PtSn catalyst

PROX reaction was studied over an unsupported PtSn catalyst. CO2 and H2O were produced from a H2 flow containing 1% CO, and 0.4–2% O2. PtSn pretreated with O2 and H2 contained more Pt in the near-surface region and was more active towards CO oxidation than a sample pretreated in H2 only. In situ XPS was also carried out during PROX reaction. Sn 3d indicated the presence of Sn-oxides, near to the surface region, along with Pt3Sn. Pt 4f peak showed metallic Pt under all conditions. Water and OH enrichment was observed in the O 1s spectrum, taken during PROX reaction.

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► Unsupported PtSn was more active catalyst in PROX than Pt black.
► Pretreatment by H2 and by O2–H2 increased activity.
► PROX activity had a sharp maximum at about 400 K.
► In situ XPS: Pt 4f showed Pt0, Sn 3d contained Sn0 and Sn oxides.
► Whenever surface OH, H2O are present, PROX reaction is more rapid.