Systems and methods for making a middle distillate product and lower olefins from a hydrocarbon feedstock

1. A method comprising:

catalytically cracking a gas oil feedstock within an FCC riser reactor zone by contacting under suitable catalytic cracking conditions including a temperature of from 450 to 550° C., within said FCC riser reactor zone said gas oil feedstock with a first catalyst comprising a molecular sieve having cracking activity dispersed in a porous inorganic refractory oxide matrix or binder, to yield an FCC riser reactor product comprising a cracked gas oil product and a first used cracking catalyst, wherein the gas oil feedstock comprises a first portion comprising a heavy hydrocarbon feedstock and a second portion comprising at least one of a fatty acid and a fatty acid ester having from about 12 to about 25 carbon atoms;

providing an intermediate reactor feedstock, wherein the wherein the intermediate reactor feedstock comprises a first portion comprising a hydrocarbon feedstock having a boiling temperature in the gasoline range and a second portion comprising at least one of a fatty acid and a fatty acid ester having from about 6 to about 10 carbon atoms;

contacting the intermediate reactor feedstock with a second catalyst comprising a molecular sieve having cracking activity dispersed in a porous inorganic refractory oxide matrix or binder within an intermediate cracking reactor operated under suitable high severity cracking conditions including a temperature of from about 482° C. to about 871° C., to so as to yield a cracked intermediate reactor product, comprising at least one lower olefin compound, and a second used cracking catalyst; and

separating said cracked intermediate reactor product into a lower olefin product comprising said at least one lower olefin compound.

2. The method of claim 1 , further comprising regenerating said first used catalyst to yield a regenerated first catalyst.

3. The method of claim 1 , further comprising using at least a portion of said second used catalyst as said first catalyst.

4. The method of claim 2 , further comprising using at least a portion of said regenerated first catalyst as said second catalyst.

5. The method of claim 1 , further comprising: using said lower olefin compound as an olefin feed to a polyolefin manufacturing system.

6. The method of claim 1 , further comprising introducing into said intermediate cracking reactor a ZSM-5 additive.

7. The method of claim 1 , wherein said suitable catalytic cracking conditions are sufficient to provide for a conversion of said gas oil feedstock in the range of from 40 to 90 weight percent of the total gas oil feedstock.

8. The method of claim 1 , wherein first portion comprises from 70 to 95 percent of the intermediate reactor feedstock, and the second portion comprises from 5 to 30 percent of the intermediate reactor feedstock.

9. The method of claim 8 , wherein first portion comprises from 80 to 90 percent of the intermediate reactor feedstock, and the second portion comprises from 10 to 20 percent of the intermediate reactor feedstock.

10. The method of claim 1 , wherein the second used cracking catalyst from the intermediate reactor is split into two portions, one portion of which is sent to the FCC riser reaction zone and another portion is sent to a regenerator.

11. The method of claim 1 , wherein second catalyst employed in the intermediate reactor is a middle distillate selective cracking catalyst.

12. The method of claim 11 , wherein a ZSM-5 additive is used along with the middle distillate selective catalyst in the intermediate reactor.