INVESTIGATION OF THE SMSI PHENOMENON WITH TIO2/RU/SIO2 MODEL-DISPERSED CATALYSTS

The response of ternary SiO2-supported Ru/TiO2 catalysts to a series of characteristic treatments has been examined in detail by chemisorption measurements, XPS, SIMS, and HREM observations, appropriate comparisons being made with binary Ru/SiO2 and Ru/TiO2 reference samples. The SMSI state is shown to be air-sensitive and the active highly dispersed phases on the ternary TiO2/ Ru/SiO2 catalysts exhibit SMSI behavior even after low-temperature reduction. SIMS and XPS data indicate that the SMSI condition does not involve intermixing of the Ru and TiO2 phases. Rather it is associated with highly dispersed metal entities whose XP spectra exhibit significant surface core-level binding energy shifts. Further aspects of the SMSI state are also discussed. © 1991.