Deep Hydrodesulfurization of Dibenzothiophenes Over NiW Sulfide Catalysts Supported on Sol–Gel Titania–Alumina

This work showed that the use of Al₂O₃–TiO₂ as carriers has a positive effect on the activity of supported NiW catalysts in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene carried out in a batch reactor at 320 °C and total H₂ pressure of 5.5 MPa. Two Al₂O₃–TiO₂ mixed oxides with Al/Ti atomic ratios of 10 and 2 were synthesized by sol–gel method together with the pure Al₂O₃ synthesized as reference support. For NiW/Al₂O₃–TiO₂ and NiW/Al₂O₃ catalysts, a metal load of 17 and 5.5 wt% of W and Ni were considered respectively. It was found that both Al₂O₃–TiO₂-supported catalysts exhibited higher activity than alumina-supported one. The catalyst with a largest TiO₂ content (NiW/AT2) demonstrated to be 23 % more active with respect to NiW/Al₂O₃. Solids were characterized by temperature-programmed reduction (TPR), high resolution transmission electronic microscopy and X-ray photoelectronic spectroscopy (XPS) techniques. A decrease in support–metal interaction (from TPR) was observed when Ti content increased, which could lead to a higher amount of NiWS phase (from XPS). Besides, a slight increase in the slabs length in WS₂ was observed for titania-containing catalyst with respect to NiW/Al₂O₃, indicating that the dispersion can still be optimized. The atomic ratio Al/Ti = 2 of the NiW/Al₂O₃–TiO₂ catalyst proved to be a potential substitute for current catalysts for sulfur reduction in ultra-clean diesel.