Resonance Raman spectroscopic studies of probe molecules interacting with acidic sites on silica–alumina

Abstract

Resonance Raman spectra have been recorded from Methyl Red, Ethyl Red, α-Naphthyl Red, o-aminoazotoluene and 4-(phenyl-azo)diphenylamine adsorbed from toluene solutions on to untreated and calcined silica–alumina. The spectra show clear evidence for the protonation of all five molecules, resulting from interaction with Brønsted acidic sites on the silica–alumina surface. Adsorption data over a wide range of equilibrium concentrations give satisfactory fits to Langmuir isotherms. The densities of acidic sites increase after calcination at 300°C.

References

1. J. G. Larson, H. R. Gerberich and W. K. Hall, J. Am. Chem. Soc., 1965, 87, 1880.
2. M. W. Tamele, Discuss. Faraday Soc., 1950, 8, 270.
3. M. Ai, J. Catal., 1977, 50, 291.
4. K. Tanabe, Solid Acids and Bases, Academic Press, New York, 1970.
5. P. Yarlagadda, C. R. F. Lund and E. R. Ruckenstein, J. Catal., 1990, 125, 421.
6. I. M. Campbell, Catalysis at Surfaces, Cambridge University Press, Cambridge, 1988.
7. M. R. Basila and T. R. Kantner, J. Phys. Chem., 1967, 71, 467.
8. J. E. Mapes and R. P. Eischens, J. Phys. Chem., 1954, 58, 1059.
9. M. R. Basila, T. R. Kantner and K. H. Rhee, J. Phys. Chem., 1964, 68, 3197.
10. H. A. Benesi and B. H. C. Winquist, Adv. Catal., 1978, 27, 97.
11. J. G. Larson and W. K. Hall, J. Phys. Chem., 1965, 69, 3080.
12. I. D. Gay and S. Liang, J. Catal., 1976, 44, 306.
13. S. Rajagopal, J. A. Marzari and R. Miranda, J. Catal., 1995, 151, 192.
14. K. Machida, in Raman Spectroscopy: Sixty Years On, Vibrational Spectra and Structure, ed. J. R. Durig, Elsevier, Amsterdam, 1989, vol. 17A, p. 421.
15. J. F. Brazdil and E. B. Yeager, J. Phys. Chem., 1981, 85, 995.
16. J. F. Brazdil and E. B. Yeager, J. Phys. Chem., 1981, 85, 1005.
17. J. F. Brazdil and E. B. Yeager, J. Phys. Chem., 1981, 85, 2194.
18. R. D. Place and P. K. Dutta, Anal. Chem., 1991, 63, 348.
19. A. Bisset and T. J. Dines, J. Chem. Soc., Faraday Trans., 1995, 91, 499.
20. A. Bisset and T. J. Dines, J. Raman Spectrosc., 1995, 26, 791.
21. A. Bisset and T. J. Dines, J. Raman Spectrosc., 1996, 27, 49.
22. K. Machida, B.-K. Kim, Y. Saito, K. Igarashi and T. Uno, Bull. Chem. Soc. Jpn., 1974, 47, 78.
23. J. C. Merlin, J. L. Lorriaux, A. Dupaix and E. W. Thomas, J. Raman Spectrosc., 1981, 11, 131.
24. A. Bisset and T. J. Dines, unpublished work.