Two-stage catalytic cracking process

Claim 1

PROCESS FOR THE PRODUCTION OF GASOLINE AND RELATED PRODUCTS BY THE CATALYTIC CRACKING OF HYDROCARBON OILS BOILING ESSENTIALLY ABOVE GASOLINE WHICH COMPRISES PASSING THE OIL TO BE CRACKED THROUGH A FIRST REACTION ZONE IN THE VAPOR PHASE, PASSING SIMULTANEOUSLY THROUGH SAID FIRST REACTION ZONE IN CONTACT WITH SAID OIL A FRESHLY REGENERATED FINELY DIVIDED SOLID CRACKING CATALYST, SAID PASSAGE OF CATALYST THROUGH SAID REACTION ZONE BEING AT SUCH A RATE THAT THE RESIDENCE TIME OF THE CATALYST IN SAID ZONE IS NOT ABOVE 12 SECONDS, THE HORIZONTAL CROSS-SECTION OF SAID FIRST REACTION ZONE BEING SUCH THAT THE LINEAR VELOCITY IS ABOVE THAT AT WHICH THE SOLID CATALYST WILL SEPARATE INTO A PSEUDO LIQUID PHASE, THE TEMPERATURE IN SAID REACTION ZONE BEING AT LEAST ABOUT 1000*F., SAID OIL BEING PASSED AT A SPACE VELOCITY ADJUSTED TO PROVIDE A CONVERSION OF AT LEAST 40% REMOVING HYDROCARBON OIL VAPORS SUBSTANTIALLY FREE OF CATALYST FROM SAID REACTION ZONE AND COOLING AND DISTILLING THEM TO SEPARATE AN INTERMEDIATE OIL BOILING ESSENTIALLY ABOVE GASOLINE THEREFROM, PASSING CATALYST FROM SAID FIRST REACTION ZONE AFTER A RESIDENCE TIME THEREIN OF LESS THAN 12 SECONDS TO A SECOND REACTION ZONE OF SUCH SIZE THAT THE RESIDENCE TIME THEREIN IS CONSIDERABLY LONGER THAN IN SAID FIRST REACTION ZONE, MAINTAINING SAID SECOND REACTION ZONE AT A TERMPRATURE BELOW THE SAID FIRST REACTION ZONE AND BETWEEN ABOUT 850*F. AND 975*F., PASSING THE ABOVE SAID INTERMEDIATE OIL THROUGH SAID SECOND REACTION ZONE IN CONTACT WITH THE PARTIALLY USED CATALYST THEREIN AT A SPACE VELOCITY ADJUSTED SUCH THAT THE ONVERSION THEREIN IS BETWEEN ABOUT 10% AND ABOUT 40%, REMOVING HYDROCARBON OIL VAPORS FROM SAID SECOND REACTION ZONE AND COOLING AND SEPARATELY DISTILLING THE SAME TO SEPARATE THE GASOLINE PRODUCED.