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wt. % FCC zeolite Y, the stated amount of in-situ ZSM-5, and the balance inert particles. 

<img src='content_image/931834.jpg'>

$^{1}$2.5% Example 3, 90% FCC catalyst, balance 7.5% inert microsphere. 

$^{2}$10% ZSM-5 additive and 90% FCC catalyst. 

$^{3}$Incorporated additive contains 15% ZSM-5 

$^{4}$Activity is defined as x/(1 - x), where x is the gas oil conversion. 

As can be seen from Table 8, the additive catalyst of the present invention was substantially more active than the baseline catalyst and even more active than the incorporated ~!~Jedcf~a!:~u:~;~/~~~!~ v!h;f :~:t~}i~~e ~~~~;~r;:~ additive. The addition of ZSM-5 additive to the baseline is expected to increase activity for gasoline cracking as is characterized by the reduced gasoline yield of both compo› sitions containing the additive ZSM-5 catalysts. What is surprising is that the in-situ additive at a 2.5% level (0.625% ZSM-5) is more active than the incorporated ZSM-5 addi› tive at a 10% level (1.5% ZSM-5) (gasoline 44.8 versus 47.54). Importantly, the propylene yield of the in-situ addi› tive was increased relative to the ZSM-5 incorporated additive, again even though the in-situ additive was present in smaller amounts (propylene 7.9 versus 6.8). 

What is claimed is: 

1. A process for making ZSM-5 comprising forming an aqueous reaction mixture containing calcined kaolin microspheres, a solution of seeds characterized as promoting growth of zeolite Y crystals, and silicate, said reaction 50 mixture having a mole ratio of silica to reactive alumina of at least 20 and a pH of less than 14, reacting said mixture at elevated temperature and for a time to form in-situ ZSM-5 crystals on said microspheres, said aqueous reaction mixture being free of organic templates and free of ZSM-5 seed- 55 crystals. 

2. The process of claim 1 wherein the mole ratio of silica to reactive alumina in said reaction mixture is at least 30. 

3. The process of claim 1 wherein said calcined kaolin microspheres are agitated during said reacting. 

4. The process of claim 1 wherein the pH of said reaction mixture is at a range of 10.5 to less than 14. 

5. The process of claim 1 wherein said elevated tempera› ture is 130-240° C. and said time for reaction is from about 5-30 hours. 

6. The process of claim 5 wherein said elevated tempera- ture is 150---200° C. and said time of reaction is from about 10-25 hours. 

7. The process of claim 1 wherein said reaction mixture includes an acid to provide said pH. 

8. The process of claim 1 wherein said calcined kaolin microspheres are formed from hydrous kaolin, metakaolin, kaolin calcined at a temperature of greater than 1400° F., or mixtures thereof. 

9. The process of claim 8 wherein said calcined kaolin microspheres are formed with a silica or silicate binder. 

10. The process of claim 9 wherein said calcined kaolin microspheres comprise spinel, mullite, or mixture thereof. 

11. The process of claim 9 wherein said calcined kaolin microspheres contain less than 10 wt. % metakaolin. 

12. The process of claim 9 wherein said calcined kaolin microspheres contain less than 5 wt. % metakaolin. 

13. The process of claim 1 wherein said calcined kaolin microspheres comprise silica-rich components and/or metakaolin which has been leached with an acid to extract at least a portion of the aluminum oxide content of said metakaolin. 

14. The process of claim 1 wherein said calcined kaolin microspheres have an average particle size of from about 20 to about 150 microns. 

15. The process of claim 1 wherein said calcined kaolin microspheres have an average particle size of from about 40 to about 100 microns. 

16. The process of claim 1 wherein said solution of seeds does not exhibit detectable crystallinity by x-ray diffraction. 

17. The process of claim 1 wherein said solution of seed includes zeolite Y crystals. 

18. The process of claim 1 wherein said calcined kaolin microspheres have a BET surface area of less than 200 g/m 2 . 

19. The process of claim 16 where said calcined kaolin microspheres contain less than 5 wt % metakaolin. 

20. In a process for catalytic cracking of a petroleum faction under cracking conditions in the presence of a conventional cracking catalyst and an additive catalyst com› prising ZSM-5, the improvement wherein said additive catalyst is formed by the process of claim 1. 

21. The process of claim 20 wherein said conventional cracking catalyst is zeolite Y. 

