Zirconia Pillared Clays: Synthesis, Characterization and Catalytic Properties in the NOx Selective Reduction by Hydrocarbons in the Oxygen Excess
V. A. Sadykov1,2 , T. G. Kuznetsova1, V. P. Doronin1, T. P. Sorokina1, G. M. Alikina1, D. I. Kochubei1,B. N. Novgorodov1 , E. A. Paukshtis1, V. B. Fenelonov1, V. I. Zaikovskii1, V. A. Rogov1, V. F. Anufrienko1, N. T. Vasenin1, V. A. Matyshak3, G. A. Konin3 , A. Ya. Rozovskii4, V. F. Tretyakov4, T. N. Burdeynaya4, J. R. H. Ross5 and J. P. Breen5
1G. K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences,
Pr. Akademika Lavrentyeva 5, Novosibirsk 630090 (Russia), E-mail: sadykov@catalysis.nsk.su
2Novosibirsk State University,
Ul. Pirogova 2, Novosibirsk 630090 (Russia)
3N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences,
Ul. Kosygina 4, Moscow 117977 (Russia)
4A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences,
Leninskiy pr. 29, Moscow 117912 (Russia)
5University of Limerick, Technology Park, Limerick (Ireland)
Abstract
Procedures for synthesis of thermally stable up to 750 °C zirconiα-pillared clays (ZrPC) via intercalation of a montmorillonite clay with zirconium polyoxocations modified by cations of Ce, Fe, Al, Ca, Sr, Ba, were elaborated. Optimization of the preparation procedure allowed to obtain samples with specific surface area up to 300–400 m2/g, the gallery height up to 10 Å and micropore volume up to 0.13 m2/g. Active components comprised of copper cations and/or Pt clusters were supported on ZrPC by using photoassisted deposition. The structural and surface properties of pillars and effects of mutual interaction between the nanosized zirconia particles, and metal and oxide components were elucidated by using EXAFS, UV-Vis, ESR, H2 TPR, NOx TPD and FTIRS of adsorbed CO molecules. Catalytic properties of these systems were characterized in the reactions of NOx selective reduction in the excess of oxygen by propane, propylene and decane. Strong interaction between the Pt atoms and copper cations resulted in substantial variation of the reactivity of the surface oxygen as well as bonding strength and coverages of surface ad-NOx species. It was reflected in substantial improvement of the low-temperature activity of these systems as compared with those containing separate components. The nature of cation used for pillar modification was found to affect catalytic properties of supported active components, which can be explained by variation of the pillars structure and uniformity of their spatial distribution in clay galleries.
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