ALLOY FORMATION IN SUPPORTED PT-SN CATALYSTS - MOSSBAUER STUDIES

A series of materials that contained 1 wt% Pt and Pt: Sn atomic ratios varying from 1 : 1 to 1 : 8 were prepared. These metals were supported on alumina (100 or 250 m2/g) or silica (700 M2/g). For both alumina supports, the fraction of Pt that was present in an alloy increased with increasing tin content; the data are consistent with, but do not require, an alloy with a composition of PtSn. For these materials, zero valent tin is more easily obtained following reduction in hydrogen when silica is used as the support. Mossbauer data alone indicate that an alloy richer in Sn than PtSn is present on the silica support; however, Mossbauer data combined with XRD data indicate that a PtSn alloy is formed with additional tin being in a "metallic" state. © 1991.