RESUMO
The structural and catalytic properties of SiO2- and TiO2 -supported Pt-Au bimetallic catalysts prepared by coimpregnation were compared with those of samples of similar composition synthesized from a Pt2Au4(C{triple bond}CBut)8 cluster precursor. The smallest metal particles were formed when the bimetallic cluster was used as a precursor and TiO2 as the support. FTIR data indicate that highly dispersed Au crystallites in these samples, presumably located in close proximity to Pt, are capable of linearly coordinating CO molecules with a characteristic vibration observed at 2111 cm(-1). The cluster-derived Pt2Au4/TiO2 samples were the only ones exhibiting low-temperature CO oxidation activity, indicating that both the high dispersion of Au and the nature of the support are important factors affecting the catalytic activity for this system.