In Situ EXAFS Studies of Small Fe Particles Used as Catalysts for NH3 Synthesis

  • W. Niemann
  • B. S. Clausen
  • H. Topsøe


Supported Fe particles used as catalysts for ammonia synthesis are studied by X-ray absorption measurements in a newly developed in situ cell under real reaction conditions. Starting with the precursor, various reduction stages and the final reaction conditions at high pressure and high temperature (80 bar, 400°C) have been investigated. The reduction of iron oxide and the growth of Fe particles can be directly observed in the x-ray absorption fine structure. Simultaneously, the activity of the catalyst is measured. A comparison with the absorption fine structure of an iron foil measured at the same temperature gives indications for the size of the small Fe particles in the catalyst.


Reduction Stage Iron Foil Real Reaction Condition Small Cluster Model 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    M.G. Mason, Phys. Rev. B27:748 (1983).ADSGoogle Scholar
  2. 2.
    R.C. Baetzold, Inorqan. Chem. 20:118 (1981).CrossRefGoogle Scholar
  3. 3.
    P. Stoltze and J.K. NjzSrskov, Phys. Rev. Lett. 55:2502 (1985).ADSCrossRefGoogle Scholar
  4. 4.
    B.S. Clausen, H. Topsjzie, R. Candia, J. Villadsen, B. Lengéler, J. Als-Nielsen and F. Christensen, J. Phys. Chem. 85:3868 (1981).CrossRefGoogle Scholar
  5. 5..
    B.S. Clausen, B. Lengeier, B.S. Rasmussen, W. Niemann and H. Topsøe, Journ. Physique, in pressGoogle Scholar
  6. 6..
    B.S. Clausen, W. Niemann and H. Topsøe, to be publishedGoogle Scholar
  7. 7.
    W. Malzfeldt, IaI. Niemann, R. Haensel and P. Rabe, Nucl. Instr. Meth. 208:359 (1983).CrossRefGoogle Scholar
  8. 8.
    W. Niemann, Ph.D. thesis, University of Kiel, FRG, (1985)Google Scholar
  9. 9..
    F.W. Lytle, G.H. Via and J.H. Sinfelt, in: “Synchrotron Radiation Research”, ed. by H. Winick and S. Doniach (Plenum Press, New York, 1980), p. 401.CrossRefGoogle Scholar
  10. 10.
    D.C. Koningsberger and J.W. Cook, Jr., in “EXAFS and Near Edge Structure”, ed. by A. Bianconi, L. Incoccia, S. Stipcich (Springer-Verlag, Berlin 1983), p. 412.CrossRefGoogle Scholar
  11. 11.
    R.A. Dalla Betta, M. Boudart, K. Foger, D.G. Löffler and J. Sanchez-Arrieta, Rev. Sci. Instr. 55:1910 (1984).ADSCrossRefGoogle Scholar
  12. 12.
    P.A. Lee, P.H. Citrin, P. Eisenberger, B.M. Kincaid, Rev. Mod. Phys. 53:769 (1981).ADSCrossRefGoogle Scholar
  13. 13.
    B. Lengeler, P. Eisenberger, Phys. Rev. B21:4507 (1980).ADSGoogle Scholar
  14. 14.
    B. Lengeler, Journ. Physique, in pressGoogle Scholar
  15. 15.
    R.B. Greegor, F.W. Lytle, Journ. Catalysis 63:476 (1980).CrossRefGoogle Scholar
  16. 16.
    A. Nielsen and H. Bohlbro, J. Am. Chem. Soc. 74:963 (1952) A. Nielsen, “An investigation on promoted iron catalysts for the synthesis of ammonia”, (J. Gjellerups Forlag, Kopenhagen 1968).CrossRefGoogle Scholar
  17. 17.
    P. Stoltze, private communication (1986).Google Scholar
  18. 18.
    W. Niemann, to be published.Google Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • W. Niemann
    • 1
  • B. S. Clausen
    • 1
  • H. Topsøe
    • 1
  1. 1.Haldor Topsøe Research LaboratoriesLyngbyDenmark

Personalised recommendations