Browsing by Author "Masson, J"

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Heterogeneous Structures in Promoted Chromia-PAlumina Dehydrogenation Catalysts
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (10), 1977) Masson, J; Bonnier, J. M
    The catalytic activity and various physical–chemical properties (crystallographic phase, specific surface area, electric conductivity, e.p.r.) of alkali metal doped Al2O3+ Cr2O3 catalysts (7.5 mol % Cr2O3) have been compared before and after dissolution of the superficial layers in water. The active promoters (i.e. K, Rb and Cs) extensively segregate from the bulk to the outer layers. A substantial amount of chromium is simultaneously segregated. Some of the segregated alkali metal ions are associated with segregated chromium, and form a chromate in the regenerated (i.e. oxidized) catalyst. The additional activity brought about by the promoters can be explained by the formation of incompletely coordinated Cr3+ upon reduction in isobutane in the first minutes of the catalytic run.