The particular characteristics of the active sites of MoS2, WS2 catalysts in thiophene hydrodesulfurization

It was reported in earlier studies that a linear correlation existed between the total sulfur exchange capacity and thiophene hydrodesulfurization activity of different, alumina- or silica-supported molybdenum- or tungsten-sulfide based porous catalysts promoted with different metals: Co, Ni, Pt and Pd. The aim of this study was to clear up how general the linear correlation is, whether that correlation is generally applicable, whether it shows a particular character of the active sites in thiophene hydrodesulfurization (HDS). Industrial catalysts are more complex than typical model catalysts so the extents of thiophene HDS were determined on six industrially manufactured catalysts available today (combinations of Mo, W and Ni supported on alumina and of one NiW on silica-alumina) and compared to their sulfur uptake, and radiosulfur exchange capacity at 623 K. The majority of these catalyst samples also contained some phosphorus in different amounts. The results of the cyclohexane dehydrogenation as a model reaction indicated the absence of metallic nickel on the surface of the catalysts. A linear correlation was observed between the sulfur exchange capacity and HDS activity of these catalysts (with the exception of the sample supported on silica-alumina) similar to that observed previously.