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 DRIFTS 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 Pt0 (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 Pt0 (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 Pt0 increased with time and CO pressure, which is probably characteristic for the disruption of Pt crystallites into Pt0 with the help of CO.