Thiophene, desulfurization

A mixed microbial community was isolated for thiophene desulfurization using enrichments from oilfield samples and showed the presence of biphenyl as a by-product. However, a pure strain could not be obtained due to over-competence by homo-acetogenic bacteria in the consortium [23],... 

Matsui, T. Onaka, T. Maruhashi, K., and Kurane, R., Benzo(b)thiophene desulfurization by Gordonia rubropertinctus strain T08. Applied Microbiology and Biotechnology, 2001. 57 pp. 212-215. 

Silylene and disilene adducts are obtained with dienes (equation 18). With thiophene, desulfurization takes place and the products are more complicated, as shown in equation 1949. 

Examination of the reaction products indicated that the primary products of reaction were probably butadiene and H2S. The rates of hydrogenation of butadiene and butene were found to be consistent with the amounts appearing in the reaction products (provided, in the case of cobalt molybdate catalyst, that H2S was present to simulate reaction conditions). The results support the view that C-S bond cleavage is the first step in thiophene desulfurization, rather than hydrogenation of the ring. 

The thiophene ring is not saturated prior to removal of sulfur atom. The first step may be involved with the simultaneous removal of a sulfur atom and the saturation of the hydrocarbon. Studies show that HDS and subsequent HYD reactions occur on separate sites. In case of benzothiophene, however, the thiophene ring is hydrogenated to thiophene before sulfur atom is removed and this is in contrast with thiophene desulfurization. 

The thiophene desulfurization activities of [RUC02] and [RU2C0] heterogeneous catalysts derived from carbon- and 7-alumina-supported [RuCo2(/y3-S)(CO)9] and [HRu2Co(//3-S)(CO)9], respectively, were lower at 673 K than those of catalysts containing only Ru or Co. At 423 K however, this trend was reversed. ... 

A great deal is known about the current generation of hydroprocessing catalysts. Using in-situ Mossbauer emission spectroscopy and extended x-ray absorption fine structure (EXAFS), the Haldor-Topsoe group has conclusively shown that the active sites on the sulfided C0-M0-AI2O3 catalyst are vacancies associated with the edge sites in the Co-Mo-S phase. In fact, the thiophene desulfurization rate is linearly proportional to the concentration of the Co-Mo-S phase. A... 

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