No abstract

In situ ESR spectroscopy has been used for direct comparison of different thermal and light-induced processes leading to generation of superoxide radical anions on the surface of various zirconia and sulfated zirconia materials. For materials of both types the magnetic resonance parameters of the radical anions were found to be practically independent of the generation method, except for oxygen coadsorption with NO that yields radicals with somewhat smaller gz values. The parameters appear to depend mostly on the state of the surface zirconia cations stabilizing the radical anions, so that the g tensor anisotropy is significantly smaller over sulfated zirconia. It is shown that light-induced formation of superoxide radical anions in the presence of coadsorbed hydrocarbons can be initiated with visible light. Original SIET reaction mechanisms are suggested for the formation of superoxide radical anions by coadsorption with hydrocarbons and illumination after such coadsorption to extend the previously known ones to account for the observed phenomena. Cluster model DFT calculations of magnetic resonance parameters of O2- radical anions stabilized on the surface of zirconium dioxide showed that the adsorption complexes have a -shape rather than linear structure. The magnetic resonance parameters obtained by calculations practically match experimental data and adequately describe their changes after the surface modification with sulfates.

Approaches to design of zirconia pillared clays via control of the properties of pillaring species in solutions were elaborated. Structural features of pillars and Pt + Cu active components fixed at these nanoparticles were shown to determine catalytic properties of pillared clays in NO x selective reduction by hydrocarbons in the oxygen excess.KEY WORDS: zirconia pillared clay; synthesis; structure of zirconia nanoparticles and texture of clays; copper and Pt-loaded catalysts; reducibility and adsorption properties; catalysis of NO x HC SCR; performance and reaction mechanism

No abstract

The nanocrystalline samples of 10wt.%Scandia stabilized Zirconia (10ScSZ) and 1wt.%Ceria doped ScSZ (1Ce10ScSZ) prepared via co-precipitation route were characterized and compared to commercially available samples regarding their transport properties and electrical conductivity. The results of oxygen isotope experiments show that for Zirconia-based electrolytes, the rate of heteroexchange is lower than that for Samaria-doped Ceria. The results of Secondary Ions Mass Spectrometry (SIMS) indicate that all admixed components are present both in the surface layer and the bulk of the studied samples with pronounced segregation on the grain boundary. The highest total conductivity is observed for DKKK sample. In the range of 600-400°C the highest conductivity observed for synthesized nanocrystalline 1Ce10ScSZ sample is explained by the effect of segregated Scandia doped Ceria surface layers.