EuroPt-1 catalyst: Radial distribution of electron density X-ray diffraction and EXAFS studies

The supported Pt/SiO2 (EuroPt-1) catalyst has been studied by the radial distribution of electron density (RDED) and EXAFS techniques. The starting sample of the catalyst was stored in air, not subjected to any further treatment, and contained metal platinum Pt0 and platinum oxide PtO in a ∼1:2 ratio. An analysis of the EXAFS data was based on three possible structural models of platinum particles. Model 1 suggested that there was one Pt-Pt short contact, which was the same in the bulk of the particles and on the surface. Model 2 considered two different Pt-Pt distances for the particle volume and surface. For model 3, we additionally assumed that the corresponding Debye-Waller factors differed. For the oxidized sample, model 2 was most reliable, and the Pt-Pt distance between the surface atoms was shortened by ∼0.14 Å. For the reduced samples, the structural data obtained are consistent with model 3.