Ion-dipole interactions between adsorbed CO and support cations in Pt/K-LTL

The adsorption of carbon monoxide on a non-acidic Pt/K-LTL catalyst has been studied by diffuse reflectance and transmission IR spectroscopy. The CO spectrum isstrongly depen-dent on the experimental conditions. Adsorption on the small Pt clusters in the presence of water gives linear-CO bands between 2060 and 1990 cm-1 and a bridging-CO band around 1800 cm-l. In the absence of water, the linear bands are red shifted to about 1940 and 1720 cm-1, respectively. The frequency shift is attributed to an ion-dipole interaction between adsorbed CO and support cations. The ion~tipole interaction is screened by the adsorbed water leading to a smaller ed shift in the CO stretching frequency