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Buckypapers made with CNx nanotubes.

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Graphical abstract Abstract Individual and simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrodenitrogenation (HDN) of carbozole reactions have been studied in the presence of hydrogen (P=55 bar) at 310 ºC in a batch reactor over a series of sulfided NiMo/P/Al-HMS catalysts modified with phosphorus (0.5-2.0 wt.%). Both oxidic precursors and sulfide catalysts have been characterized by specific surface area, XRD, Raman, TPD-NH 3 , HRTEM, XPS and IR spectroscopy of adsorbed pyridine.Regardless of the reaction studied, all P-containing catalysts showed higher activity than that to the P-free one. The catalyst modified with optimized amount of P (1 wt.%) the best HDS activity and exhibited a lowest inhibition factor during simultaneous HDS and HDN, which was close to that of a commercial NiMo/Al 2 O 3 sulfide catalyst. This was linked with formation of irregular MoS 2 structures having high concentration of brim sites as well as with its largest total acidity.

Partially sulfided nanostructures were synthesized by direct sulfurization of alpha-MoO(3) nanorods using a mixture of H(2)S/H(2), 15 vol%, at several temperatures (400, 500, 600, 700, and 800 degrees C). These materials were tested as catalysts in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and characterized by specific surface areas using the expression developed by Brunauer, Emmett, and Teller (BET equation), x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM images show a gradual evolution from a smooth surface to a rough material, presenting some type of holes all over the particles, but keeping their rod-like structure throughout sulfidation. The results of evaluating the catalysts in the HDS of DBT showed that the best temperature for sulfidation is 500 degrees C. In all samples, a higher selectivity for hydrogenation over sulfur removal was observed.