HIGHLY DISPERSED PLATINUM ON TIO2 OBTAINED VIA AUTOREDUCTION OF THE PRECURSOR SPECIES

Small Pt clusters of ~10 Å were prepared by decomposition at temperatures above 200 °C and 1O-5torr of tetramine platinum(II) complex exchanged with TiO2 Degussa (P25). Decomposition of the precursor species was followed by gas chromatography and UV visible spectroscopy in the 100-400 °C temperature range. N2 desorption of the Pt/TiO2 surface involves an elementary reaction possessing 11.2 kJ mol-1 activation energy. The topology of the Pt clusters on the TiO2 surface has been examined by transmission electron microscopy (TEM) for 0.03-0.75% Pt loadings. For a 0.16% Pt-TiO2 sample, the oxidation state of the catalyst was examined by ESCA in order to assess the oxidation state of the Pt cluster as a function of the temperature of preparation. Diffuse reflectance spectroscopy (DRS) further assesses the nature of the Pt surface cluster as a function of the applied temperature. © 1990.