Ferrospinels of nickel, cobalt and copper and their sulphatcd analogues were prepared by the room temperature coprecipitation route (0 yield samples with high surface areas. The intrinsic acidity among the ferrites was found to decrease in the order: cobalt> nickel> copper. Sulphation caused an increase in the number of weak and medium strong acid sites, whereas the strong acid sites were left unaffected. Electron donor studies revealed that copper ferrite has both the highest proportion of strong sites and the lowest proportion of weak basic sites. All the ferrite samples proved 10 be good catalysts for the bcnzoy lation of toluene with benzoyl chloride. copper and cobalt ferrites being much more active than niekel ferrite. The catalytic activity for benzoylation was not much influenced by sulphation, hut it increased remarkably with calcination temperature of the catalyst. Surface Lcwis acid sites, provided by the octahedral cations on the spinel surface. are suggested to be responsible for the catalytic activity for the benzoylation reaction.

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Invertase was adsorbed onto micro-porous acid-activated montmorillonite clay (K-10) by two procedures, namely adsorption and covalent binding. The immobilized enzymes were characterized by XRD, surface area measurements and 27 Al NMR. XRD measurements revealed an expansion of clay layers due to immobilization which suggests that intercalation had taken place. Surface area measurements also support this observation. 27 Al NMR showed that interaction of enzyme with tetrahedral and octahedral Al changes with the immobilization procedure. Sucrose hydrolysis was performed in a batch reactor. The immobilized enzymes showed enhanced pH and thermal stabilities. Optimum pH and temperature were found to increase upon immobilization. The effectiveness factor (g) and Michaelis constant (K m ) suggest that diffusional resistances play a major role in the reaction. The immobilized invertase could be stored in buffer of pH 5 and 6 at 5°C without any significant loss in activity for 20 days.

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The synthesis of dimethyl acctals of carbonyl compounds such as cyclohcxanone, acetophenone, and bcnzophenone has successfully been carried out by the reaction between ketones and methanol using different solid acid catalysts. The strong influence of the · textural properties of the catalysts such as acid amount and adsorption properties (surface area and pore volume) determine thẽ catalytic activity. The molecular size of the reactants and products determine the acetalization ability of a particular ketone. The