CO-induced surface structural changes of Pt on oxide-supported Pt catalysts studied by DRIFTS

CO adsorption (0.01-10 Torr) on differently pretreated titania-, alumina-, and silica-supported 1 and 5% Pt catalysts was investigated by DRIFFS at 300 K. The three band structure observed in 0.01 Torr CO on reduced 1% Pt/oxide catalysts has been connected with the presence of monoatomic Pt-0 (2112-2106 cm(-1)), Pt atoms on edges (2070 cm(-1)), and kinked Pt atoms (2050 cm(-1)). The increase of CO pressure caused the disappearance of the bands due to CO adsorbed on edged and kinked Pt atoms, and at the same time a band due to CO linearly (on top) adsorbed on smooth Pt facets appeared at 2058-2068 cm(-1). These features were regarded as consequences of surface Pt reconstruction. CO adsorption on reduced 5% Pt/oxide catalysts did not show the presence of edged and kinked Pt atoms, as only the bands due to CO adsorbed on monoatomic Pt-0 (2105-2109 cm(-1)) and CO linearly (on top) adsorbed on smooth Pt facets (2066-2076 cm(-1)) were observed. The intensity of the band due to CO adsorbed on monoatomic Pt-0 increased with time and CO pressure, which is probably characteristic for the disruption of Pt crystallites into Pt-0 with the help of CO. (C) 2003 Elsevier Science (USA). All rights reserved.