Alkylation Performance of Thiophene and Its Derivatives during Olefinic Alkylation of Thiophenic Sulfur in Gasoline

The alkylation performance of thiophene and its derivatives (such as 2-methylthiophene, 3-methylthiophene, and 2,5-dimethylthiophene) with 1-hexene was investigated in a fixed-bed reactor. The results showed that thiophene and all its derivatives could be mono-alkylated with 1-hexene easily, and their conversion was close to 100% under experimental conditions. However, with the increase of the number of the branched chain on the thiophene ring, the di- and tri-alkylation capability of thiophene derivatives decreased a lot because of the thermodynamics and steric effects, and their primary products are restricted to the mono-alkylated products. The decrease in alkylation capability of thiophene derivatives enhanced the other two parallel competitive reactions, the aromatics alkylation and alkene alkylation (or called alkene oligomerization). The relative content of their further alkylated products was even more than that of the mono-alkylated products during the alkylation of dimethylthiophene.