Maximization of FCC light olefins by high severity operation and ZSM-5 addition

The effects of high severity operation and ZSM-5 addition on the FCC produc t yield structure have been studied in a MAT unit. VGO cracking at high rea ction temperatures of 500-650 degrees C increases the yield of light olefin s (propylene and butenes) with a corresponding loss in gasoline yield and i ncrease in dry gas formation. Similar behavior is observed with the additio n of 0-20 wt.% ZSM-5 additive, however, with no increase in dry gas. The co mbination of the two effects (high severity and ZSM-5 addition) makes the F CC unit an excellent source of light olefins for downstream petrochemical a nd alkylation units. A novel downer reactor FCC configuration is proposed t o suppress thermal cracking reactions and dry gas formation during high sev erity operation. (C) 2000 Elsevier Science B.V. All rights reserved.