Catalytic conversion of hydrocarbons with catalyst activity adjustment

Claim 1

IN A CYCLICALLY OPERATING CATALYTIC CRACKING SYSTEM, IN WHICH A CATALYST CYCLES THROUGH REACTION AND REGENERATION, THAT METHOD OF CHANGING THE PRODUCT DISTRIBUTION OF THE REACTION WHICH COMPRISES WITHDRAWING A FIRST CATALYST FROM THE SYSTEM AFTER ITS REGENERATION, AT A HIGH RATE, OF THE ORDER OF ABOUT HALF THE RATE AT WHICH CATALYST IS CIRCULATED WITHIN THE SYSTEM AND ADDING TO THE SYSTEM AN AMOUNT, EQUAL TO THAT WITHDRAWN, OF A SECOND CATALYST, THE SECOND CATALYST BEING HEATED TO A TEMPERATURE SUBSTANTIALLY THE SAME AS THAT OF THE CIRCULATING CATALYST AT THE POINT OF INTRODUCTION OF THE SECOND CATALYST TO MAINTAIN WITHOUT SUBSTANTIAL CHANGE THE OPERATING VARIABLES OF THE SYSTEM IN WHICH ONE CATALYST IS A COMPOSITE OF A SILICEOUS ACIDIC CRACKING COMPONENT AND A RATE-EARTH EXCHANGED CRYSTALLINE ALUMINOSILICATE.