Hydrodesulfurization of Dibenzothiophene over Ni-Mo-W Sulfide Catalysts Supported on Sol-Gel Al(2)O(3)-CeO(2)

To achieve sulfur content in gas oil at a near-zero level, new catalysts with improved hydrogenation functions are needed. In this work, new Ni-Mo-Mo hydrodesulfurization (HDS) catalysts supported by Al(2)O(3)-CeO(2) materials were synthesized to evaluate their efficiency in the reaction of HDS with dibenzothiophene (DBT). Al(2)O(3)-CeO(2) supports different CeO(2) loadings (0, 5, 10 and 15 wt.%) and supported NiMoW catalysts were synthesized by sol-gel and impregnation methods, respectively. The physicochemical properties of the supports and catalysts were determined by a variety of techniques (chemical analysis, XRD, N(2) physisorption, DRS UV-Vis, XPS, and HRTEM). In the DBT HDS reaction carried out in a batch reactor at 320 °C and a H(2) pressure of 5.5 MPa, the sulfide catalysts showed a dramatic increase in activity with increasing CeO(2) content in the support. Nearly complete DBT conversion (97%) and enhanced hydrogenation function (HYD) were achieved on the catalyst with the highest CeO(2) loading. The improved DBT conversion and selectivity towards the hydrogenation products (HYD/DDS ratio = 1.6) of this catalyst were attributed to the combination of the following causes: (i) the positive effect of CeO(2) in forcing the formation of the onion-shaped Mo(W)S(2) layers with a large number of active phases, (ii) the inhibition of the formation of the undesired NiAlO(4) spinel phase, (iii) the appropriate textural properties, (iv) the additional ability for heterolytic dissociation of H(2) on the CeO(2) surfaces, and (v) the increase in Brønsted acidity.