Abstract: The transformation mechanism of dibenzothiophene (DBT) in FCC process was studied on a fixed fluidized bed unit in laboratory using DBT containing hexadecane as feed. Test results showed that under the conditions of a reaction temperature of 500 ℃, a catalyst to oil mass ratio of 6 and a space velocity of 10 h-1, the conversion of DBT was about 45%. Alkylation reactions were the main reactions in which DBT took place. The main product was methtyl-benzothiophene and followed by C2~C5 alkyl-DBT. Nearly 90 percentage of the sulfur in the DBT-hexadecane reaction system was distributed in the liquid products, only a small portion was converted to H2S and coke. The presence of DBT reduced the conversion of hexadecane, the yield of gasoline fractions decreased, the yields of dry gas, diesel fractions and coke increased.

Key words: catalytic cracking, dibenzothiophene, Sulfur transformation