METHODS FOR PREPARING THERMALLY STABLE AND ACTIVE ACID CATALYSTS BY INCORPORATION OF LANTHANUM INTO Y, DESILICATED Y-ZEOLITE AND X-ZEOLITE

The incorporation of La3+ ions by ion exchange into the Na forms of X, Y and desilicated Y zeolites does not alter the thermal stability of these materials, while it dramatically increases their activity in the acid-catalysed hydrocracking/hydroisomerization of n-octane. On the other hand, lanthanum ions, when ion-exchanged into the ammonium forms of these zeolites, stabilize the acid forms currently obtained by calcination of the corresponding ammonium zeolites at high temperatures. Interestingly, high catalytic performances are obtained when the amount of La3+ ions incorporated into the Na forms of these zeolites is equal to or higher than 70% of the cationic capacity of these materials, which now become as active and selective as the LaH or ultrastabilized HY zeolites.