Advertisement

The European Physical Journal E

, Volume 12, Supplement 1, pp 35–38 | Cite as

Gas diffusion in zeolite beds: PFG NMR evidence for different tortuosity factors in the Knudsen and bulk regimes

  • S. Vasenkov
  • O. Geir
  • J. Kärger
Article

Abstract.

Self-diffusion of ethane in beds of zeolite NaX is studied using Pulsed Field Gradient (PFG) NMR. The ethane diffusivities were measured for displacements, which are orders of magnitude larger than the size of individual crystals. These diffusivities were compared with those, calculated using simple gas kinetic theory. The results of the comparison indicate that for the same bed of NaX crystals the apparent tortuosity factor in the Knudsen regime (i.e. when molecule-solid collisions dominate) is significantly larger than that in the bulk regime (i.e. when molecule-molecule collisions dominate). This finding is attributed to the more pronounced geometrical trapping by the pore structure of the zeolite bed in the Knudsen than in the bulk regime.

PACS codes.

47.55.Mh - Flows through porous media 81.05.Rm - Porous materials; granular materials 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1. W.G. Pollard, R.D. Present, Phys. Rev. 73, 762 (1948)CrossRefGoogle Scholar
  2. 2. V.N. Burganos, J. Chem. Phys. 109, 6772 (1998) CrossRefGoogle Scholar
  3. 3. G.L. Vignoles, J. Phys. IV France 5, 159 (1995)Google Scholar
  4. 4. M.M. Tomadakis, S.V. Sotirchos, AIChE J. 39, 397 (1993)Google Scholar
  5. 5. R.W. Mair, G.P. Wong, D. Hoffmann, M.D. Hürlimann, S. Patz, L.M. Schwartz, R.L. Walsworth, Phys. Rev. Lett. 83, 3324 (1999)CrossRefGoogle Scholar
  6. 6. J. Kärger, D.M. Ruthven, Diffusion in Zeolites and Other Microporous Solids (Wiley, New York, 1992)Google Scholar
  7. 7. J. Kärger, M. Kocirik, A. Zikanova, J. Colloid Interface Sci. 84, 240 (1981)Google Scholar
  8. 8. F. Rittig, C.G. Coe, J.M. Zielinski, J. Am. Chem. Soc. 124, 5264 (2002)CrossRefGoogle Scholar
  9. 9. P. Galvosas, F. Stallmach, G. Seiffert, J. Kärger, U. Kaess, G. Majer, J. Magn. Reson. 151, 260 (2001)CrossRefGoogle Scholar
  10. 10. R.M. Cotts, M.J.R. Hoch, T. Sun, J.T. Markert, J. Magn. Reson. 83, 252 (1989)Google Scholar
  11. 11. L.Z.Wang, A. Caprihan, E. Fukushima, J. Magn. Reson. A 117, 209 (1995)CrossRefGoogle Scholar
  12. 12. E.J. Fordham, P.P. Mitra, L.L. Latour, J. Magn. Reson. A 121, 187 (1996)CrossRefGoogle Scholar
  13. 13. J.G. Scland, G.H. Sorland, K. Zick, B. Hafskjold, J. Magn. Reson. 146, 14 (2000)CrossRefGoogle Scholar
  14. 14. S. Vasenkov, P. Galvosas, O. Geier, N. Nestle, F. Stallmach, J. Kärger, J. Magn. Reson. 149, 228 (2001)CrossRefGoogle Scholar
  15. 15. S.P. Zhdanov, S.S. Khvoshchev, N.N. Feoktistova, Synthetic Zeolites (Gordon & Breach, New York, 1990)Google Scholar
  16. 16. P. Lorenz, M. Bülow, J. Kärger, Colloids Surf. 11, 353 (1984)CrossRefGoogle Scholar
  17. 17. P.L. McDaniel, C.G. Coe, J. Kärger, J.D. Moyer, J. Phys. Chem. 100, 16263 (1996)CrossRefGoogle Scholar
  18. 18. J.A. Dunne, M. Rao, S. Sircar, R.J. Gorte, A.L. Myers, Langmuir 12, 5896 (1996)CrossRefGoogle Scholar
  19. 19. O. Grubner, P. Jira, M. Ralek, Molekularsiebe (VEB Deutscher Verlag der Wissenschaften, Berlin, 1968)Google Scholar
  20. 20. Landolt-Börnstein, Zahlenwerte und Funktionen aus Physik, Chemie, Astronomie, Geophysik und Technik, 6th edn, Vol. 1, Part 1 (Springer-Verlag, Berlin, Göttingen, Heidelberg, 1950, p. 323)Google Scholar
  21. 21. F.A. Dullien, Porous Media: Fluid Transport and Pore Structure (Academic Press, New York, 1976)Google Scholar
  22. 22. P. Levitz, J. Phys. Chem. 97, 3813 (1993)Google Scholar
  23. 23. K. Malek, M.-O. Coppens, Phys. Rev. Lett. 87, 125505-1 (2001)CrossRefGoogle Scholar

Copyright information

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003

Authors and Affiliations

  • S. Vasenkov
    • 1
  • O. Geir
    • 1
  • J. Kärger
    • 1
  1. 1.Universität Leipzig, Abteilung Grenzflächenphysik, Linnéstr. 5, 04103, Leipzig, Germany

Personalised recommendations