Alloy formation in Pt$z.sbnd;Sn$z.sbnd;alumina catalysts: In situ X-ray diffraction study

Changes in PtSnalumina catalysts, prepared from the (Pt3Sn8Cl30)2− complex, during reduction in flowing hydrogen were followed by in situ X-ray diffraction (XRD). For high metal loading (ca. 5% Pt) evidence was found for both PtSn and Pt phases: other PtSn phases, such as Pt3Sn, PtSn2, and PtSn4, were not observed. Metallic Pt was detected for a 0.6 wt% PtAl2O3 catalyst but only a PtSn alloy was observed for a 0.6 wt% Pt catalyst containing Sn. In situ XRD studies therefore support alloy formation with a stoichiometry of Pt: Sn = 1: 1; the Sn in excess of that needed to form this alloy is present in an X-ray “amorphous” form.