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The acidity of trivalent cation-exchanged montmorillonite. II. Desorption of mono- and di-substituted pyridines

Published online by Cambridge University Press:  09 July 2018

C. Breen
C. Breen*
Affiliation:
Chemistry Department, Sheffield City Polytechnic, Pond Street, Sheffield, S1 1WB, UK
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Abstract

Temperature programmed desorption (TPD) and IR spectroscopy were used to examine the desorption of pyridine, 2-methyl-, 4-methyl- and 2,6-dimethylpyridine from Al3+- and Cr3+-montmorillonite. Pyridine desorbed from Lewis sites at 150°C and from Bronsted sites at 340°C. 4-methylpyridine desorbed from Lewis and Bronsted centres at 210°C and 410°C respectively, some 60°C higher than pyridine due to its higher basicity. Conversely, the 2-methyl- and 2,6-dimethylpyridine, which are sterically hampered with respect to their coordination to Lewis centres, desorbed from these sites near 100°C, but due to their greater basicity desorbed from Bronsted sites at higher temperatures. These interpretations were confirmed by IR spectroscopy.

Type
Research Article
Information
Clay Minerals , Volume 23 , Issue 3 , September 1988 , pp. 323 - 328
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1988

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References

Ballantine, J.A. (1986) The reactions in clays and pillared clays. Pp. 197–212 in: Chemical Reactions in Organic and Inorganic Constrained Systems.(Setton, R., editor). D. Reidel, Holland.CrossRefGoogle Scholar
Ballantine, J.A., Graham, P., Patel, I., Purnell, J.H., Williams, K. & Thomas, J.M. (1987) New differential thermogravimetric method using cyclohexylamine for measuring the concentration of interlamellar protons in clay catalysts. Proc. Int. Clay Conf. Denver, 311–318.Google Scholar
Benesi, H.A. (1973) Determination of proton acidity of solid catalysts by chromatographic adsorption of sterically hindered amines. J. Catal. 28, 176–178.Google Scholar
Breen, C., Deane, A.T. & Flynn, J.J. (1987) The acidity of trivalent cation exchanged montmorillonite. Temperature programmed desorption and infrared studies of pyridine and «-butylamine. Clay Miner., 22, 169–178.Google Scholar
Corma, A., Fornes, V. & Ortega, E. (1985) The nature of acid sites on fluorinated γ-Al2O3 J. Catal., 92, 284–290.Google Scholar
Deane, A.T. (1987) Physicochemical studies of clay-organic interactions. PhD thesis, NIHE, Dublin.Google Scholar
Jacobs, P.A. & Heylen, C.F. (1974) Active sites in zeolites. III. Selective poisoning of Bronsted sites on synthetic Y zeolites. J. Catal., 34, 267–274.Google Scholar
Knozinger, H. & Stolz, H. (1971) IR-spektroskopische unterschung der adsorption von methylpyridinen an A1203. Ber. Bunsenges. Phys. Chem., 75, 1055–1063.Google Scholar
Mortland, M.M. & Raman, K.V. (1968) Surface acidity of smectites in relation to hydration, exchangeable cation and structure. Clays Clay Miner., 16, 393–398.Google Scholar
Russell, J.D. (1965) Infra-red study of the reactions of ammonia with montmorillonite and saponite. Trans. Farad. Soc., 61, 2284–2294.Google Scholar
Thomas, J.M. (1982) Sheet silicate intercalates: new agents for unusual chemical conversions. Pp. 56-97 in: Intercalation Chemistry(Whittingham, M. S. & Jacobson, A. J., editors). Academic Press, New York.Google Scholar
Tronconi, E. & Forzatti, P. (1985) Experimental criteria for diffusional limitations during temperature- programmed desorption from porous catalysts. J. Catal., 93, 197–200.Google Scholar