While rising the automobile octane number of the re-resolution mannered null naphtha of the cat naphtha in order

摘要

PROBLEM TO BE SOLVED: To provide a recracking method so designed as to add light cat naphtha and steam to a reaction zone and subject the light cat naphtha together with heavy stock to a fluid catalytic cracking to obtain lower olefins and high- octane automotive gasoline in high yield. ;SOLUTION: This method comprises: introducing a hot reclaimed catalyst A10 into a riser reactor 34 comprising an upstream reaction zone R₁34 and downstream reaction zone R₂36; bringing A10 into contact with a light cat naphtha B22 at 620 to 775°C in R₁34 for less than 1.5 s of a steam retention time of a steam D24 to effect cracking part or the whole of 5-9C olefins into 3-4C olefins; bringing a reaction mixture from R₁34 into contact with a heavy stock 28 such as (depressurized) gasous oil at 600 to 750°C in R₂36 for less than 20 s of a steam retention time; separating a waste catalyst A', cracked product and D from R₁34 and R₂36 into a cracked product E containing B and D, and A' in the separation zone; recirculating a part or the whole of E to R₁34; and stripping A' in the stripping zone and then introducing it to the reclaiming zone for reclaiming A'.;COPYRIGHT: (C)1998,JPO