Gasoline octane enhancement in fluid catalytic cracking process with split feed injection to riser reactor

Abstract

A fluid catalytic cracking unit equipped with multiple feed injection points along the length of the riser is operated such that portions of the same fresh feed are charged to different feed injection points. Preferably, the hydrocarbon fresh feed can be split into two or more non-distinct fractions, with one fraction charged to the bottom injection point along the length of the riser reactor, and the remaining fractions charged to injection points progressively higher up along the length of the riser reactor. Unconverted slurry oil boiling above 650 DEG F. can be recycled to one or more of the various injection points along the length of the riser.

What is claimed is: 
     
       1. A process for the conversion of unsegregated hydrocarbon feed in an FCC riser reactor employing zeolitic catalyst .Iadd.to produce gasoline .Iaddend.which comprises: (a) splitting the hydrocarbon feed and injecting at a plurality of positions along a length of said FCC riser reactor, wherein about 60 to 75 volume percent of said feed is injected to the lowest injection position, and the distance between said lowest injection position and the next highest injection position comprises at least 20% of the total length of said riser reactor;   (b) selecting the number of feed splits and selecting said positions along said length of said FCC riser reactor, to maximize the octane number of the gasoline;   (c) recycling regenerated catalyst into the bottom of said FCC riser reactor; and   (d) lifting said regenerated catalyst up said FCC riser reactor said injection position of said hydrocarbon .[.oil.]. feed with a flow of catalytically inert gas.   
     
     
       2. A process for the conversion of unsegregated hydrocarbon feed in an FCC riser reactor employing zeolitic catalyst .Iadd.to produce gasoline .Iaddend.which comprises: (a) injecting said hydrocarbon feed at a plurality of positions along a length of said FCC riser reactor, wherein about 60 to 75 volume percent of said feed is injected to the lowest injection position, and the distance between said lowest injection position and the next highest injection position comprises at least 20% of the total length of said riser reactor;   (b) apportioning throughput through said position along said length of said FCC riser reactor to maximize octane number of the gasoline;   (c) recycling regenerated catalyst into the bottom of said FCC riser reactor; and   (d) lifting said regenerated catalyst up said FCC riser reactor to said injection position of said hydrocarbon .[.oil.]. feed with a flow of catalytically inert gas.   
     
     
       3. The process of claim.[.s.]. 1 .[.and.]. .Iadd.or .Iaddend.2 wherein one of the upper injection points is located in the reactor or stripper vessel. 
     
     
       4. The process of claim.[.s.]. 1 .[.and.]. .Iadd.or .Iaddend.2 which further comprises: recycling unconverted slurry oil to one or more injection positions along the length of the riser. 
     
     
       5. The process of claim 4 wherein said slurry oil comprises material boiling above 650° F. 
     
     
       6. The process of claim.[.s.]. 1 .[.and.]. .Iadd.or .Iaddend.2 wherein said catalytically inert gas is steam. 
     
     
       7. The process of claim.[.s.]. 1 .[.and.]. .Iadd.or .Iaddend.2 wherein said catalytically inert gas is recycled absorber gas. 
     
     
       8. The process of claim.[.s.]. 1 .[.and.]. .Iadd.or .Iaddend.2 wherein said catalytically inert gas is gas selected from the group consisting of hydrogen, hydrogen sulfide, ammonia, methane, ethane, propane, and combinations thereof. .Iadd. 
     
     
       9.  A process for conversation of a full boiling range unsegregated hydrocarbon feed in an FCC riser reactor employing zeolitic catalyst to produce gasoline which comprises: a) injecting said hydrocarbon feed at a plurality of positions along the length of said FCC riser reactor, wherein about 60 to 75 volume percent of said feed is injected to the lowest injection position, and the distance between said lowest injection position and the next highest injection position comprises at least 20% of the total length of said riser reactor;   b) apportioning throughput through said position along said length of said FCC riser reactor to maximize octane number of the gasoline;   c) recycling generated catalyst into the bottom of said FCC riser reactor; and   d) lifting said regenerated catalyst up said FCC riser reactor to said injection position of said hydrocarbon feed with a flow of catalytically inert gas. .Iaddend..Iadd.   
     
     
       10.  The process of claim 9 wherein one of the upper injection points is located in the reactor or stripper vessel. .Iaddend..Iadd.11. The process of claim 9 which further comprises recycling unconverted slurry oil to one or more injection positions along the length of the riser. .Iaddend..Iadd.12. The process of claim 11 wherein said slurry oil comprises material boiling above 650° F. .Iaddend..Iadd.13. The process of claim 9 wherein said catalytically inert gas is steam. .Iaddend..Iadd.14. The process of claim 9 wherein said catalytically inert gas is recycled absorber gas. .Iaddend..Iadd.15. The process of claim 9 wherein said catalytically inert gas is selected from the group consisting of hydrogen, hydrogen sulfide, ammonia, methane, ethane, propane or combinations thereof. .Iaddend..Iadd.16. The process of claim 9 wherein all of said feed is apportioned between said lowest injection position and one higher injection position. .Iaddend..Iadd.17. A process for the conversion of a full boiling range unsegregated hydrocarbon feed in a vertically elongated FCC riser reactor employing zeolitic catalyst to produce gasoline comprising: a) injecting a first portion of said feed to a first injection position at the bottom of said riser reactor wherein about 60 to 75 volume percent of said feed is injected to the first injection position;   b) injecting the remaining portion of said feed at a second injection position in said riser reactor, said second injection position at a higher elevation in said riser reactor than said first injection position and wherein the distance between said first injection position and said second injection position is at least 20% of the said FCC riser reactor;   c) apportioning throughput throughout said first and second injection positions along said riser reactor to increase the octane number of gasoline product over that obtainable when said entire feed is injected at said first feed position under the same reactor conditions;   d) recycling regenerated catalyst to the bottom of said FCC riser reactor; and   e) lifting said regenerated catalyst up said FCC riser reactor to said first injection position of said hydrocarbon feed with a flow of   
     
     
        catalytically inert gas. .Iaddend..Iadd.18.  The process of claim 17 wherein said catalytically inert gas is steam. .Iaddend..Iadd.19. The process of claim 17 wherein said gas is selected from the group consisting of hydrogen, hydrogen sulfide, ammonia, methane, ethane, propane, and 
     
     
        combinations thereof. .Iaddend..Iadd.20.  The process of claim 1 wherein said zeolitic catalyst comprises a zeolite selected from the group consisting of rare earth exchanged X, rare earth exchanged Y, hydrogen Y, ultrastable Y, superstable Y and ZSM-5. .Iaddend..Iadd.21. The process of claim 20 wherein said zeolite is selected from the group consisting of rare earth exchanged Y and ZSM-5. .Iaddend..Iadd.22. The process of claim 2 wherein said zeolitic catalyst comprises a zeolite selected from the group consisting of rare earth exchanged X, rare earth exchanged Y, hydrogen Y, ultrastable Y, superstable Y and ZSM-5. .Iaddend..Iadd.23. The process of claim 22 wherein said zeolite is selected from the group consisting of rare earth exchanged Y and ZSM-5. .Iaddend..Iadd.24. The process of claim 9 wherein said zeolitic catalyst comprises a zeolite selected from the group consisting of rare earth exchanged X, rare earth exchanged Y, hydrogen Y, ultrastable Y, superstable Y and ZSM-5. .Iaddend..Iadd.25. The process of claim 24 wherein said zeolitic catalyst comprises a zeolite selected from the group consisting of rare earth exchanged Y and ZSM-5. .Iaddend..Iadd.26. The process of claim 17 wherein said zeolitic catalyst comprises a zeolite selected from the group consisting of rare earth exchanged X, rare earth exchanged Y, hydrogen Y, ultrastable Y, superstable Y and ZSM-5. .Iaddend..Iadd.27. The process of claim 26 wherein said zeolite is selected from the group consisting of rare earth exchanged Y and ZSM-5. .Iaddend.