Catalysis Letters

, Volume 20, Issue 1–2, pp 23–36 | Cite as

A combined QEXAFS/XRD method for on-line, in situ studies of catalysts: Examples of dynamic measurements of Cu-based methanol catalysts

  • Bjerne S. Clausen
  • Lars Gråbæk
  • Gert Steffensen
  • Poul L. Hansen
  • Henrik Topsøe
Article

Abstract

The development of a new in situ method which allows high quality XRD and EXAFS to be obtained on-line under ideal catalytic conditions is discussed. The possibility to obtain both types of information simultaneously enables a much better structural description of catalytic materials which typically contain both crystalline and X-ray amorphous structures. The system employs a capillary tube as the microreactor/in situ cell. The high degree of temperature uniformity of the cell and the possibilities of fast changes in reaction conditions make the system ideal for dynamic studies. For this purpose, the EXAFS measurements are carried out in the newly developed quick scanning mode (QEXAFS) which also allows high quality data to be obtained. The XRD is acquired using a position sensitive detector. The application of the setup for time resolved measurements is demonstrated in a study of the calcination and reduction of Cu-based methanol catalysts where the changes take place over a few degrees. The high quality of the data made it possible to obtain important new insight regarding the presence of intermediate phases during these processes. Studies of Cu/SiO2 catalysts show the advantages of a newly developed theory for a better estimation of coordination numbers (and thus particle sizes) from EXAFS.

Keywords

EXAFS QEXAFS XRD methanol catalyst molecular dynamics in situ studies Cu catalysts 

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References

  1. [1]
    R. Prins and D.C. Koningsberger, in:X-ray Absorption: Principles, Applications, Techniques of EXAFS, SEXAFS and XANES, eds. D.C. Koningsberger and R. Prins (Wiley, New York, 1988) p. 321.Google Scholar
  2. [2]
    B.S. Clausen, G. Steffensen, B. Fabius, J. Villadsen, R. Feidenhans'l and H. Topsøe, J. Catal. 132 (1991) 524.Google Scholar
  3. [3]
    B.S. Clausen, L. Gråbæk, G. Steffensen and H. Topsøe, HASYLAB Annual Report (1991) p.495;Google Scholar
  4. [3] a
    B.S. Clausen, L. Gråbæk, G. Steffensen, P.L. Hansen and H. Topsøe, HASYLAB Annual Report (1992) p.223.Google Scholar
  5. [4]
    J.W. Couves, J.M. Thomas, D. Waller, T.H. Jones, A.J. Dent, G.E. Derbyshire and G.N. Greaves, Nature 354 (1991) 465.Google Scholar
  6. [5]
    A.J. Dent, M.P. Wells, R.C. Farrow, C.A. Ramsdale, G.E. Derbyshire, G.N. Greaves, J.W. Couves and J.M. Thomas, Rev. Sci. Instr. 63 (1992) 903.Google Scholar
  7. [6]
    R. Frahm, Nucl. Instr. Meth. Phys. Res. A 270 (1988) 578.Google Scholar
  8. [7]
    B.S. Clausen, L. Gråbæk, H. Topsøe, L.B. Hansen, P. Stoltze, J.K. Nørskov and O.H. Nielsen, J. Catal. 140 (1993), in press.Google Scholar
  9. [8]
    B.S. Clausen, H. Topsøe, L.B. Hansen, P. Stoltze and J.K. Nørskov, Japan. Appl. Phys., in press.Google Scholar
  10. [9]
    B.S. Rasmussen, P.E. Højlund Nielsen, J. Villadsen and J.B. Hansen, in:Preparation of Catalysts, Vol. 4, eds. B. Delmon, P. Grange, P.A. Jacobs and G. Poncelet (Elsevier, Amsterdam, 1987) p. 785.Google Scholar
  11. [10]
    J.A. van Dillen, J.W. Geus, L.A.M. Hermans and J. van der Meijden, in:Proc. 6th Int. Congr. on Catalysis, eds. G.C. Bond, P.E. Wells and F.C. Tompkins (The Chemical Society, London, 1976) p. 677.Google Scholar
  12. [11]
    K. Klier, Appl. Surf. Sci. 19 (1984) 267.Google Scholar
  13. [12]
    G.C. Chiunchen, K.C. Waugh and D.A. Whan, Appl. Catal. 25 (1986) 101.Google Scholar
  14. [13]
    R. Burch, S.E. Golunski and M.S. Spencer, Catal. Lett. 5 (1990) 55.Google Scholar
  15. [14]
    K. Shimomura, K. Ogawa, M. Oba and Y. Kotera, J. Catal. 52 (1978) 191.Google Scholar
  16. [15]
    K. Tohji, Y. Udagawa, T. Mizushima and A. Ueno, J. Phys. Chem. 89 (1985) 5671.Google Scholar
  17. [16]
    B.S. Clausen, B. Lengeler, B.S. Rasmussen, W. Niemann and H. Topsøe, J. Phys. (Paris) C8 (1986) 237.Google Scholar
  18. [17]
    T.L. Neils and J.M. Burlitch, J. Catal. 118 (1989) 79.Google Scholar
  19. [18]
    D. Duprez, Z. Fer-Hamida and M.M. Bettahar, J. Catal. 124 (1990) 1.Google Scholar
  20. [19]
    B.S. Clausen and H. Topsøe, Catal. Today 9 (1991) 189.Google Scholar
  21. [20]
    G.D. Moggridge, T. Rayment, R.M. Ormerod, M.A. Morris and R.M. Lambert, Nature 358 (1992) 658.Google Scholar
  22. [21]
    L.B. Hansen, P. Stoltze, J.K. Nørskov, B.S. Clausen and W. Niemann, Phys. Rev. Lett. 64 (1990) 3155.Google Scholar
  23. [22]
    D.E. Sayers, E.A. Stern and F.W. Lytle, Phys. Rev. Lett. 27 (1971) 1204.Google Scholar
  24. [23]
    B.S. Clausen, H. Topsøe, L.B. Hansen, P. Stoltze and J.K. Nørskov, Paper to be presented at the National ACS Meeting, Chicago, Illinois, 22–27 August 1993.Google Scholar

Copyright information

© J.C. Baltzer AG, Science Publishers 1993

Authors and Affiliations

  • Bjerne S. Clausen
    • 1
  • Lars Gråbæk
    • 1
  • Gert Steffensen
    • 1
  • Poul L. Hansen
    • 1
  • Henrik Topsøe
    • 1
  1. 1.Haldor Topsøe Research LaboratoriesLyngbyDenmark

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