FCC process using a modified catalyst

1. A method for fluidized catalytic cracking, comprising:

cracking a mixed C4 feed stream in the presence of a catalyst under conditions sufficient to produce an effluent comprising ethylene, propylene, gasoline, and a coked-catalyst, wherein the catalyst comprises a first catalytic component having an average pore size of less than 6.4 Å and a second catalytic component having an average pore size of 6.4 Å or more;

separating the effluent to provide a recovered coked-catalyst and a cracked product, wherein the coked-catalyst comprises between 1.5% and 5% coke by weight of the mixed C4 feed stream; and

regenerating the recovered coked-catalyst to produce heat and the catalyst.

2. The method of claim 1 , wherein the conditions comprise temperatures from about 590° C. to about 675° C. and pressures from about 68 kPa to about 690 kPa.

3. The method of claim 1 , wherein the first catalytic component has an average pore size from about 5 Å to about 6 Å.

4. The method of claim 1 , wherein the first catalytic component is ZSM-5.

5. The method of claim 1 , wherein the second catalytic component has an average pore size from about 6.4 Å to about 50 Å.

6. The method of claim 1 , wherein the second catalytic component is zeolite Y.

7. The method of claim 1 , wherein the second catalytic component is an active matrix component.

8. The method of claim 1 , wherein the hydrocarbon has a sulfur concentration of less than 200 ppmw.

9. The method of claim 1 , wherein the hydrocarbon is substantially free of sulfur.

10. The method of claim 1 , wherein the gasoline has a diene concentration of less than about 0.5 wt %.

11. A method for fluidized catalytic cracking, comprising:

cracking a mixed C4 feed stream in the presence of a catalyst and a sulfur containing compound under conditions sufficient to produce an effluent comprising ethylene, propylene, gasoline, and a coked-catalyst, wherein the catalyst comprises a first catalytic component having an average pore size from about 5 Å to about 6 Å and a second catalytic component having an average pore size of 6.4 Å or more, and wherein the gasoline has a diene content of less than about 3 wt %;

separating the effluent to provide a recovered coked-catalyst and a cracked product, wherein the coked-catalyst comprises between 1.5% and 5% coke by weight of the mixed C4 feed stream; and

regenerating the recovered coked-catalyst to produce heat and the catalyst.

12. The method of claim 11 , wherein the first and second conditions comprise a temperature from about 590° C. to about 675° C. and a pressure from about 68 kPa to about 690 kPa.

13. The method of claim 11 , wherein the first catalytic component is ZSM-5 and the second catalytic component is zeolite Y, USY, or an active matrix component.

14. The method of claim 11 , wherein the first catalytic component is ZSM-5 and the second catalytic component is peptized pseudoboehmite alumina.

15. A method for fluidized catalytic cracking, comprising:

cracking a mixed C4 feed stream in the presence of a catalyst under conditions sufficient to produce an effluent comprising ethylene, propylene, gasoline, and a coked-catalyst, wherein the catalyst comprises a first catalytic component having an average pore size of about 5.2 Å to about 5.8 Å and a second catalytic component having an average pore size of 6.4 Å or more, and wherein the hydrocarbon comprises one or more C 4 -C 8 hydrocarbons;

separating the effluent to provide a recovered coked-catalyst and a cracked product, wherein the coked-catalyst comprises between 1.5% and 5% coke by weight of the mixed C4 feed stream; and

regenerating the recovered coked-catalyst to produce heat and the catalyst.

16. The method of claim 15 , wherein the first catalytic component is ZSM-5 and the second catalytic component is zeolite Y.

17. The method of claim 15 , wherein the gasoline has a diene concentration of less than about 0.5 wt %.

18. The method of claim 15 , wherein the feed and the cracked product are substantially free of sulfur.