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Abstract:
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Zeolites have established themselves as industrial catalysts for over two
decades for a variety of hydrocarbon processing reactions where acidity and shape
selectivity are important factors. As solid catalysts, zeolites may be advantageous and
superior compared to their homogenous counterparts due to their characteristic
properties. It is only in recent years that the utility of zeolites for organic synthesis is
recognized for producing specific organic intermediates and fine chemicals in high
selectivity.
In this thesis an attempt has been made to compare the catalytic activity of
some medium and large pore zeolites in a few alkylation and acylation reactions. The
work reported in the present study is basically centered around the following zeolites
namely, ZSM-5, mordenite, zeolite Y and beta. The major reactions carried out were
benzoylation of o-xylene, propionylation of toluene and anisole and benzylation of oxylene.
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The programme involves the synthesis, modifications and characterization of
the zeolite catalysts by various methods. The influence of various parameters such as
non-framework cations, Si/Al ratio of zeolites, temperature of the reaction, catalyst
concentration, molar ratio of the reactants and recycling of the catalysts were also
examined upon the conversion of reactants and the formation of the desired products
in the alkylation/ acylation reactions.
The general conclusions drawn by us from the results obtained are summarized
in the last chapter of the thesis. Zeolite beta ofi'ers interesting opportunities as a
potential catalyst in alkylation reactions and the area of catalysis by medium and large
pore zeolites is very fascinating and there is plenty of scope for further research in this
field. Moreover, zeolite based catalysts are effective in meeting current industrial
processing and more stringent environment pollution limits. |