Iron and mixed iron aluminium pillared montrnorillonites prepared by partial hydrolysis method were subjected to room temperature
exchange with transition metals of the first series. The resulting materials were characterised by different spectroscopic techniques
and surface area measurements. About 1-3% transition metals were incorporated into the porous network. The structural
stability of the porous network was not affected by exchange. XRD and AI NMR spectroscopy evidenced the presence of iron
substituted Al13 like polymers in FeAl pillared systems. Acidity and basicity benefited much as a result of metal exchange. Acidity
and basicity were quantified by model reactions, viz., cumene cracking and cyclohexanol decomposition respectively. The presence
of basic sites in otherwise acidic pillared clays, though diminutive in amount can be of much importance in acid base catalysed
reactions.
Sugunan, S; Kumaree Seena, C R(Indian Journal of Chemistry, May , 1998)
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Abstract:
We have investigated the changes in surface acidity/basicity
and catalytic pro~erties of samarium oxide due to surface modification
by SO42- ion. The acidity/basicity of the catalysts is
determined by titration method using Hammett indicators.
Esterification of acetic acid by n-butanol is chosen as a test
reaction. Sm203, owing to its high basicity and low acidity, does
not catalyze the reaction. But sulphated Sm20J catalyzes the
esterification reaction effectively. Activation temperature does
not have much effect on the acidity of sulphated samaria.