Comparison of the morphology and HDS activity of ternary Ni(Co)-Mo-W catalysts supported on Al-HMS and Al-SBA-16 substrates

This research compares the hydrodesulphurization (HDS) activity of supported Co(Ni)-Mo-W ternary catalysts with respect to the nature of the support (hexagonal mesoporous silica (HMS) versus SBA-16 material having cage-like mesoporous structure), the type of promoter (Co vs. Ni) and the nature of Al species formed after support modification with Al. Both Al-HMS and Al-SBA-16 mesoporous silica substrates were prepared by the one-pot sol–gel synthesis method via the neutral templating pathway using dodecylamine and Pluronic F127 as surfactants, respectively. The oxide precursors were characterized by a variety of techniques (N2 adsorption–desorption isotherms, XRD, DRS UV–vis spectroscopy and 27Al NMR), whereas sulphided catalysts were characterized by XPS and HRTEM, and tested in the HDS of DBT conducted in a high-pressure batch reactor at T = 350 °C and P = 3.1 MPa. The activity results revealed that NiMoW/Al-HMS catalyst was more active than all Co-promoted catalysts (including a commercial CoMo/Al2O3 catalyst). The HDS activity was found to be markedly influenced by the textural properties of support and the dispersion of the active phases on the catalyst surface. It has been hypothesised that the presence of extraframework AlNO3 phases on the surface of CoMoW/Al-SBA16 compromises its HDS activity because of the formation of a less active “onion-type” Mo(W)S2 structure.

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► HDS activity is markedly influenced by the type of promoter and support used.
► Ni promoter is much more effective than Co.
► Al-HMS is more effective than the Al-SBA-16 counterpart.
► The presence of extraframework AlNO3 phases on catalyst surface favours the formation of a less active “onion-type” Mo(W)S2 phases.