Abstract: The impact of non-basic nitrogen compounds represented by indole on FCC reaction and the contribution and conversion rule of these compounds during the process was studied in a fixed fluidized bed (FFB). The results showed that the addition of non-basic nitrogen compounds reduces the conversion of FCC process, and influences the product distribution. The higher the nitrogen content in feedstock, the greater the influence on the reactions. In the catalytic cracking reaction of indole, the nitrogen in the raw material oil was distributed in gasoline distillates, diesel distillates, coke and heavy oil fractions were 12.58%, 54.15% and 24.88% respectively. In addition, 4.46% nitrogen was converted into ammonia, and the nitrogen in the heavy oil distillate was less than 5%. Indole is the most susceptible to alkylation during catalytic cracking. Due to hydrogen transfer reaction, the nitrogen-containing heteroatomic ring of indole molecule is saturated, and then converted further into aniline or ammonia through the ring-opening cracking reaction. Ammonia reacts with olefin to form aniline and further quinoline. The macromolecular nitrogen compounds are generated from small molecule nitrogen compounds by cyclization and condensation reactions.

Key words: fluid catalytic cracking, non-basic nitrogen compound, indole, conversion rule