The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of an unsupported rhenium sulfide and a sulfided CoMo/Al2O 3-SiO2 catalyst are compared using 4,6- diethyldibenzothiophene (46DEDBT) and 3-ethylcarbazole (3ECBZ) as probe molecules. The active site densities and adsorption-reaction rate constants are determined from transient experiments. It is found that ReS2 has an unusually high selectivity toward hydrogenation. As such, it has a far higher activity than CoMo/Al2O3-SiO2 for desulfurizing 46DEDBT in the absence of 3ECBZ. The higher activity of ReS2 arises from a higher turnover frequency as the active site density on ReS2 is about one-third that on CoMo/Al2O3-SiO2. Due to ReS2's higher hydrogenation power, the HDS of 46DEDBT on ReS 2 is less resilient to 3ECBZ inhibition than that on CoMo/Al 2O3-SiO2. ReS2 shows about a sevenfold activity advantage over the CoMo/Al2O3-SiO 2 catalyst in the hydrodenitrogenation of 3ECBZ. The results shed some light on the HDS-HDN interactions in real-feed deep HDS. ?? 2010 Elsevier Inc. All rights reserved.
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