Surface-grafted mixed metal clusters

B. Structures and Catalytic Evaluation of Surface-Grafted Mixed Metal Clusters... 

Addition of Ir to a Pt/Al203 catalyst by two different methods, successive impregnation and organometallic grafting resulted in catalysts with different stracture in the first case separate Pt and Ir sites can be suggested, while in the second case, Ir was exclusively deposited on Pt, forming veiy small Ir clusters on Pt particles. Addition of Ge or Sn to the Pt-Ir grafted catalyst led to third component deposit on the surface of mixed metals particles. On the other hand, when the promoter is added to PtIr-IS, Ge seems to be located on Ir particles while Sn modified Pt particles. 

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