Calcination of the MCM-41 mesophase: mechanism of surfactant thermal degradation and evolution of the porosity

(Note: The full text of this document is currently only available in the PDF Version )

Matthew T. J. Keene, Regis D. M. Gougeon, Renaud Denoyel, Robin K. Harris, Jean Rouquerol and Philip L. Llewellyn


Abstract

Sample controlled thermal analysis (SCTA) has been used to carefully and reproducibly eliminate the organic surfactant template from pure silica mesoporous MCM-41. The reproducibility allowed a number of intermediate species to be isolated permitting complementary measurements. To understand the mechanisms by which the surfactant is removed, evolved gas analysis as well as 1H and 13C MAS NMR were used. The liberation of the porosity and evolution of the surface hydrophobicity were followed by gas adsorption, XRD and immersion microcalorimetry.

It would seem that two types of cetyltrimethylammonium surfactant exist in the confined state, of which the large majority decomposes at a lower temperature (up to 200[thin space (1/6-em)]°C) within the silica organic host than in the pure state. A small quantity of organic fragments are still observed within the pore structure up to 500[thin space (1/6-em)]°C. Gas adsorption shows a pore blocking effect occurs during the surfactant removal.


References

  1. J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T. Kresge, K. D. Schmitt, C. T.-U. Chu, D. H. Olsen, E. W. Sheppard, S. B. McCullen, J. B. Higgins and J. L. Schlenker, J. Am. Chem. Soc., 1992, 114, 10 834 CrossRef CAS.
  2. C. T. Kresge, M. E. Leonowicz, W. J. Roth, J. C. Vartuli and J. S. Beck, Nature, 1992, 359, 710 CrossRef CAS.
  3. See for example, various articles in Stud. Surf. Sci. Catal., 1998, 117 Search PubMed.
  4. R. Schmidt, D. Akporiaye, M. Stöcker and O. H. Ellestad, Stud. Surf. Sci. Catal., 1994, 84, 61 CAS.
  5. A. Corma, V. Fornés, M. T. Navarro and J. Pérez-Pariente, J. Catal., 1994, 148, 569 CrossRef CAS.
  6. A. Montes, E. Cosenza, G. Giannetto, E. Urquieta, R. A. de Melo, N. S. Gnep and M. Guisnet, Stud. Surf. Sci. Catal., 1998, 117, 237 CAS.
  7. S. Hitz and R. Prins, J. Catal., 1997, 168, 194 CrossRef CAS.
  8. S. Kawi and M. W. Lai, Chem. Commun., 1998, 1407 RSC.
  9. P. T. Tanev and T. J. Pinnavaia, Chem. Mater., 1996, 8, 2068 CrossRef CAS.
  10. X. S. Zhao, G. Q. Lu, A. K. Whittaker, G. J. Millar and H. Y. Zhu, J. Phys. Chem. B, 1997, 101, 6525 CrossRef CAS.
  11. M. T. J. Keene, R. Denoyel and P. L. Llewellyn, Chem. Commun., 1998, 2203 RSC.
  12. J. Rouquerol, J. Thermal Anal., 1989, 144, 209 Search PubMed.
  13. R. Schmidt, M. Stöcker, E. Hansen, D. Akporiaye and O. H. Ellestad, Microporous Mater., 1995, 3, 443 CrossRef CAS.
  14. O. Franke, G. Schulz-Ekloff, J. Rathousky, J. Starek and A. Zunkal, J. Chem. Soc., Chem. Commun., 1993, 724 RSC.
  15. P. J. Branton, P. G. Hall and K. S. W. Sing, J. Chem. Soc., Chem. Commun., 1993, 1257 RSC.
  16. P. L. Llewellyn, Y. Grillet, F. Schüth, H. Reichert and K. K. Unger, Microporous Mater., 1994, 3, 345 CrossRef CAS.
  17. M. Grün, I. Lauer and K. Unger, Adv. Mater., 1997, 9, 254 CrossRef.
  18. H. P. Lin, S. Cheng and C.-Y. Mou, J. Chin. Chem. Soc., 1996, 43, 375 CAS.
  19. J. Rouquerol, S. Bordère and F. Rouquerol, Thermochim. Acta, 1992, 203, 193 CrossRef CAS.
  20. S. Partyka, F. Rouquerol and J. Rouquerol, J. Colloid Interface Sci., 1979, 68, 21 CAS.
  21. R. Denoyel, F. Rouquerol and J. Rouquerol, in Fundamentals of Adsorption, ed. A. J. Liapis, Engineering Foundation, New York, 1987, p. 199 Search PubMed.
  22. K. S. W. Sing, D. H. Everett, R. A. W. Haul, L. Moscou, R. A. Pierotti, J. Rouquerol and T. Siemieniewska, Pure Appl. Chem., 1985, 57, 603 CrossRef CAS.
  23. L.-Q. Wang, J. L. Liu, G. J. Exarhos and B. C. Bunker, Langmuir, 1996, 12, 2663 CrossRef CAS.
  24. M. T. Janicke, C. C. Landry, S. C. Christiansen, D. Kumar, G. D. Stucky and B. F. Chmelka, J. Am. Chem. Soc., 1998, 120, 6940 CrossRef CAS.
  25. D. A. Spagnolo, Y. Maham and K. T. Chang, J. Phys. Chem., 1996, 100, 6626 CrossRef CAS.
  26. Y. Grillet and P. L. Llewellyn, in The Surface Properties of Silica, ed. A. P. Legrand, J. Wiley & Sons, Chichester, 1998, p. 60 Search PubMed.
  27. L. M. Parker, D. M. Bibby and J. E. Patterson, Zeolites, 1984, 14, 168 CrossRef CAS.
Click here to see how this site uses Cookies. View our privacy policy here.