Fluid catalytic cracking of gas oil and 3-4C aromatisation - in separate riser reactors with a faujasite catalyst

摘要

The fluid catalytic cracking of high-boiling hydrocarbon fractions and low-boiling C3/C4 - rich fractions is carried out by (a) passing a suspension of faujasite catalyst in the high-boiling hydrocarbon at 950-1100 degrees F through a 1st riser reactor with a residence time of 2-10 sec.; (b) discharging the suspension into a sepn. zone above a fluid bed of catalyst and passing the sepd. catalyst into the fluid bed; (c) mixing the catalyst in the upper part of the bed with a C3/C4 -rich feed to form a suspension at 700-1050 degrees F; (d) passing this suspension through a 2nd riser reactor extending from the upper part of the catalyst bed to the upper part of a catalyst/hydrocarbon vapor sepn. zone; (e) separating the suspension into hydrocarbon product and catalyst; and (f) recovering the products from both reactors and passing the catalyst from both reactors to a stripping zone and then to a regenerator. In the 2nd riser reactor, the C3/C4 fraction undergoes H-transfer and cyclisation to produce significant amts. of isobutane and aromatics.