Sulfonic acid ion-exchange resins as catalysts in nonpolar media: II. Influence of conditioning methods on the acidity and catalytic activity

The behaviour of macroporous sulfonated styrene-divinylbenzene copolymers has been investigated in relation to their acidity and catalytic efficiency in the alkylation of benzene with propene. In order to optimize catalyst activity, the following separate parameters have to be taken into account: Adsorbed water lowers the catalytic activity, but after an induction period the poisoning effect of water is at least partially offset by the interaction of the sulfonic acid groups with the olefin. The optimal drying temperature is 100°C; higher temperatures cause a sharp decrease in catalyst acidity and therefore lower catalyst activity. In addition, the perfusion of the dried resin with benzene can produce a considerable decrease in catalyst activity. The deactivation caused by elevated drying temperatures and by interaction with benzene is discussed in terms of their effect on the flexibility of the polymer backbone.