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 o ther hand, lanthanum ions, when ion-exchanged into the ammonium forms of these zeolites, stabilize the acid forms currently obtained by calc ination of the corresponding ammonium zeolites at high temperatures. I nterestingly, high catalytic performances are obtained when the amount of La3+ ions incorporated into the Na forms of these zeolites is equa l to or higher than 70% of the cationic capacity of these materials, w hich now become as active and selective as the LaH or ultrastabilized HY zeolites.