| 摘要 |
2130816 9322400 PCTABS00027 In a process for catalytically cracking a heavy feed in a single riser reactor (10) FCC unit, the catalyst inventory contains 3-10 wt % of a shape selective zeolite, preferably ZSM-5, in the form of a separate additive particle. The addition of such a large quantity of ZSM-5 as a separate additive produces unexpectedly large amounts of C3/C4 olefins. A high catalyst/feed mix temperature in the base of the riser (10) is preferably employed and the mixture quenched, preferably with a recycled heavy naphtha or light cycle oil, at a distance at least 10 % of the length of the riser (10) upstream from the outlet (20) and preferably after at least 1 second of riser (10) cracking.
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