Formation of sulfur-containing compounds under fluid catalytic cracking reaction conditions

Reactions of Organic Sulfur and Nitrogen Compounds in the FCC Pretreater and the FCC Unit

“…It is possible to produce the gasoline thiophenic sulfur compounds through the cracking of heavier alkylthiophenes, alkylbenzothiophenes, or other heavy sulfur containing molecules present in the FCC feedstock. Recent results suggest that benzothiophene and its alkylated derivatives may also be formed during cyclization and dehydrogenation of long-chain alkylthiophenes.…”

“…These compounds will thus be present in the FCC gasoline but are not originally present in the FCC feed. Leflaive et al , have reported that alkylthiophenes under FCC conditions are formed from transformation of hexene in the presence of H 2 S over a FCC catalyst. Pentadiene and hexadiene give the same products but a slightly different product distribution.…”

“…It is the general belief that sulfur in gasoline is present as stable fragments formed by dealkylation partial cracking of higher molecular weight sulfur compounds. 1,[7][8][9][10][11] In a study, 12 it was shown that the concentration of sulfur in gasoline only to a very low degree depends on conversion but that the dependence increases with increasing temperature in the FCCU. FCC catalysts with higher hydrogen transfer activity tend to produce less sulfur in gasoline.…”

“…The amount of NH 3 formed in the reactor from conversion of the organic nitrogen compounds and in particular the noncarbazole compounds react with the olefins or diolefins also produced as a consequence of the hydrocarbon cracking reactions. This was also proposed for the analogous sulfur compounds by Leflaive et al 9 The aromatic and aliphatic amines formed undergo cyclization and dehydrogenation reactions into aniline and indole compounds according to the reaction schemes shown in Figure 11.…”

“…It is the general belief that sulfur in gasoline is present as stable fragments formed by dealkylation partial cracking of higher molecular weight sulfur compounds. ,− In a study, it was shown that the concentration of sulfur in gasoline only to a very low degree depends on conversion but that the dependence increases with increasing temperature in the FCCU. FCC catalysts with higher hydrogen transfer activity tend to produce less sulfur in gasoline. , Catalysts containing REY, REUSY, and Lewis acid materials were developed as gasoline sulfur reduction catalysts or additives. − The mechanism of the sulfur reduction additives was explained by these materials having a higher hydrogen transfer activity , and by the alkylthiophenes having a higher desulphurization activity.…”