|
|
|
|
Catalytic properties of cobalt-molybdenum/alumina (CMA), nickel-molybdenum/alumina (NMA), nickel-tungsten/alumina (NWA) and nickel-tungsten/silica-alumina (NWSA) catalysts, in hydrodesulfurization (HDS) of benzothiophene were studied. The study was pursued on five types of reaction: HDS, hydrogenation of benzothiophene without HDS, hydro-ring-opening of benzothiophene without HDS, addition reaction of HDS intermediates and hydrogenation of HDS products.
In the reactions of HDS and hydrogenation without HDS, both CMA and NMA catalysts showed the highest and comparable activities and NWSA catalyst showed the lowest activity, while in the addition reaction, NWSA catalyst showed the highest activity. In the reactions of hydro-ring-opening of benzothiophene without HDS and of hydrogenation of HDS products, CMA and NMA catalysts showed higher but different activities.
In the hydro-ring-opening of benzothiophene, CMA catalyst showed much higher activity, which suggests that the rupture of C-S bonds without HDS does not relate to HDS directly. The hydrogenation of HDS products consists of two reactions: hydrogenation of ethylbenzene and hydrogenation of addition products. The NMA catalyst showed higher activity in the former reaction while the CMA catalyst showed rather higher activity in the latter reaction.