Effect of Indium Doping of γ-Alumina on the Stabilization of PtSn Alloyed Clusters Prepared by Surface Organostannic Chemistry

The control of the atomic-scale properties of highly dispersed multimetallic particles represents a challenging question for the optimal use of metallic active centers in nanoscience. In particular, improving the formation of PtxSn alloyed clusters on γ-alumina of a size close to 1 nm with a high Sn0/Pt ratio represents a crucial step toward more selective heterogeneous catalysts. For that purpose, bimetallic SnPt-based and trimetallic SnPtIn-based catalysts were prepared by surface organostannic chemistry on monometallic Pt and bimetallic PtIn-based catalysts. These systems were characterized by a multitechnique approach combining CO chemisorption, temperature programmed reduction, scanning transmission electron microscopy, Mossbauer spectroscopy, and X-ray absorption spectroscopy. The nature of the PtSn phase in trimetallic SnPtIn-based catalysts is found to strongly depend on the way indium is initially introduced in the parent catalyst, by either wet impregnation or coprecipitation with aluminum precu...