PREPARATION OF PT-CU SIO2 BY SURFACE REDOX REACTION/

Pt-Cu/SiO2 bimetallic catalysts were prepared by reduction of cupric i ons on Pt by using hydrogen preadsorbed on that metal. According to th e overall reaction CU<SUP>2+</SUP> + 2Pt-H<INF>ads</INF>-->Pt<INF>2</I NF>-Cu + 2E<SUP> </SUP>one copper atom is deposited on two accessible Pt atoms. The reaction would occur by two successive steps involving t he addition of one hydrogen atom. On well dispersed platinum catalysts deposition of copper occurs by building tridimensional deposits when on large particles copper is deposited as adatoms statistically disper sed on platinum surface.