Most of the benzene in the gasoline pool comes from reformate. Reformate, the high-octane blending component from a reformer unit, comprises about 30 vol% of the gasoline pool. Depending on the reformer feedstock and severity, reformate contains 3 5 vol% benzene.
FCC gasoline contains 0.5 1.3 vol% benzene. Since it accounts for about 35 vol% of the gasoline pool, it is important to know what affects the cat cracker gasoline benzene levels. The benzene content in the FCC gasoline can be reduced by the following:
• Short contact time in the riser and in the reactor dilute phase
• Lower catalyst to oil ratio and lower reactor temperature
• A catalyst with less hydrogen transfer.