| 摘要 |
An FCC process for obtaining light olefins comprises contacting a hydrocarbon feed stream with blended catalyst comprising regenerated catalyst and coked catalyst. The catalyst has a composition including a first component and a second component. The second component comprises a zeolite with no greater than medium pore size wherein the zeolite comprises at least 1 wt-% of the catalyst composition. The contacting occurs in a riser to crack hydrocarbons in the feed stream and obtain a cracked stream containing hydrocarbon products including light olefins and coked catalyst. The cracked stream is passed out of an end of the riser such that the hydrocarbon feed stream is in contact with the blended catalyst in the riser for less than or equal to 2 seconds on average. The hydrocarbon products including light olefins are separated from the coked catalyst. The first portion of the coked catalyst is passed to a regeneration zone in which coke is combusted from the catalyst to produce a regenerated catalyst. A second portion of the coked catalyst is blended with the regenerated catalyst and introduced to the riser. The regenerated catalyst has substantially the same relative proportions of the first component and the second component as the blended catalyst that contact the hydrocarbon feed stream. |
