Catalysis Letters

, Volume 48, Issue 1–2, pp 47–54 | Cite as

Laser Raman spectroscopy (LRS) and time differential perturbed angular correlation (TDPAC) study of surface species on Mo/SiO2 and Mo,Na/SiO2. Their role in the partial oxidation of methane

  • A.J. Marchi
  • E.J. Lede
  • F.G. Requejo
  • M. Rentería
  • S. Irusta
  • E.A. Lombardo
  • E.E. Miró


Silica-supported molybdenum (1.6 and 5.0 wt%) and molybdenum (5 wt%)-sodium (0.4 wt%) catalysts have been characterized by laser Raman spectroscopy (LRS), time differential perturbed angular correlation (TDPAC), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The presence of different molybdenum species was correlated with activity and selectivity to formaldehyde during the methane partial oxidation reaction. The main species identified on the Mo(5.0 wt%) /SiO2 surface were MoO3 and monomeric species with a single Mo=O terminal bond. The pre-impregnation of the silica support with sodium strongly diminishes the Mo=O concentration due to the formation of Na2Mo2O7 species and tetrahedral monomers with a high degree of symmetry. As a result of these modifications, both methane conversion and formaldehyde formation are strongly inhibited. The combination of LRS and TDPAC techniques resulted in a powerful tool for the identification and quantification of the molybdenum species present on the surface of a silica support.


Electric Field Gradient Methane Conversion Monomeric Species Laser Raman Spectroscopy Time Differential Perturb Angular Correlation 


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  1. [1]
    A. Bielanski and J. Haber, Catal. Rev. Sci. Eng. 19 (1979) 1.Google Scholar
  2. [2]
    M.M. Koranne, J.G. Goodwin Jr. and G. Marcelin, J. Catal. 148 (1994) 369.CrossRefGoogle Scholar
  3. [3]
    N.D. Spencer, J. Catal. 109 (1988) 187.CrossRefGoogle Scholar
  4. [4]
    N.D. Spencer, C.J. Pereira and R.K. Grasselli, J. Catal. 126 (1990) 546.CrossRefGoogle Scholar
  5. [5]
    M.A. Ba~nares, N.D. Spencer, M.D. Jones and I.E. Wachs, J. Catal. 146 (1994) 204.CrossRefGoogle Scholar
  6. [6]
    M.A. Bañares and J.L.G. Fierro, in: Catalytic Selective Oxidation, ACS Symposium Series 523, eds. S.T. Oyama and J.W. Hightower (Am. Chem. Soc., Washington DC, 1993) p. 354.Google Scholar
  7. [7]
    M.M. Koranne, J.G. Goodwin Jr. and G. Marcelin, J. Phys. Chem. 97 (1993) 673.CrossRefGoogle Scholar
  8. [8]
    B. Kartheuser and B.K. Hodnett, J. Chem. Soc. Chem. Commun. (1993) 1093.Google Scholar
  9. [9]
    S. Irusta, A.J. Marchi, E.A. Lombardo and E.E. Miró, Catal. Lett. 40 (1996) 9.CrossRefGoogle Scholar
  10. [10]
    S. Irusta, L. Cornaglia, E.E. Miró and E.A. Lombardo, J. Catal. 156 (1995) 167.CrossRefGoogle Scholar
  11. [11]
    K. Suzuki, T. Hayakawa, M. Shimizu and K. Takehira, Catal. Lett. 30 (1995) 167.CrossRefGoogle Scholar
  12. [12]
    M. Smith and U. Ozkan, J. Catal. 142 (1993) 226.CrossRefGoogle Scholar
  13. [13]
    C.C. Willams, J.G. Ekerdt, J.M. Jengh, F.D. Hardcastle, A.M. Turek and I.E.Wachs, J. Phys.Chem. 95 (1991) 8781.CrossRefGoogle Scholar
  14. [14]
    D.S. Kim, K. Segawa, T. Soeya and I.E. Wachs, J. Catal. 136 (1992) 539.CrossRefGoogle Scholar
  15. [15]
    T. Butz, C. Vogdt, A. Lerf and H. Knözinger, J. Catal. 116 (1989) 31.CrossRefGoogle Scholar
  16. [16]
    H. Frauenfelder and R.M. Steffen, in: Alpha-, Beta-, Gamma-Ray-Spectroscopy, Vol. 2, ed. K. Siegbahn (North-Holland, Amsterdam, 1965) p. 917.Google Scholar
  17. [17]
    M. del Arco, S.R.G. Carrazán, C. Martín, V. Rives, J.V. García-Ramos and P.Carmona, Spectrochim. Acta 50A (1994) 2215.CrossRefGoogle Scholar
  18. [18]
    M.A.Vuurman and I.E. Wachs, J. Phys. Chem. 96 (1992) 5008.CrossRefGoogle Scholar
  19. [19]
    M. de Boer, A.J. van Dillen, D.C. Koningsberger, J.W. Geus, M.A.Vuurman and I.E.Wachs, Catal. Lett. 11 (1991) 227.CrossRefGoogle Scholar
  20. [20]
    N. Nakamoto, Infrared and Raman Spectroscopy of Inorganic and Coordination Compounds (Wiley, NewYork, 1978).Google Scholar
  21. [21]
    I.E.Wachs, Catal. Today 27 (1996) 437.Google Scholar
  22. [22]
    V.H.J. Becker, Z. Anorg.Allg. Chem. 474 (1981) 63.Google Scholar
  23. [23]
    C.C. Williams, J.G. Ekerdt, J.-M. Jehng, F.D. Hardcastle and I.E.Wachs, J. Phys. Chem. 95 (1991) 8791.CrossRefGoogle Scholar
  24. [24]
    C. Vogdt, T. Butz, A. Lerf and H. Knözinger, J. Catal. 116 (1989) 31.CrossRefGoogle Scholar
  25. [25]
    F.G. Requejo, A.G. Bibiloni, H. Saitovitch and P.R.J. Silva, Phys. Stat. Sol. (a) 120 (1990) 105.Google Scholar
  26. [26]
    F.G.Requejo and A.G. Bibiloni, Langmuir 12 (1996) 51.CrossRefGoogle Scholar
  27. [27]
    A. Ralston and H.S. Wilf, eds., Mathematical Methods for Digital Computers (Wiley, NewYork, 1962) ch. 7.Google Scholar
  28. [28]
    F.A. Schröder, Acta Cryst. B 31 (1975) 2294.CrossRefGoogle Scholar
  29. [29]
    I.D. Brown and R.D. Shannon, Acta. Cryst. A 29 (1973) 266.CrossRefGoogle Scholar
  30. [30]
    E. Payen, J. Grimblot and J. Kasztelan, J. Phys. Chem. 91 (1987) 6642.CrossRefGoogle Scholar
  31. [31]
    Y. Okamoto and T. Imanaka, J. Phys. Chem. 92 (1988) 7102.CrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • A.J. Marchi
  • E.J. Lede
  • F.G. Requejo
  • M. Rentería
  • S. Irusta
  • E.A. Lombardo
  • E.E. Miró

There are no affiliations available

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