Insight of 1D gamma-Al2O3 nanorods decoration by NiWS nanoslabs in ultra-deep hydrodesulfurization catalyst

摘要

Novel 1D-gamma-Al2O3 nanorods were used to prepare a NiW hydrodesulfurization catalyst. Acid/base measurements of the NiW/Al-catalyst revealed a mainly weak and lower acidity and a great quantity of Lewis sites in oxide/sulfided forms. HRTEM exposed a homogeneously distributed active phase all over the surface of the Al-nR supported catalyst. Marked differences on the stacking degree and slabs length were observed when compared both materials. The activity for NiW/Al-nR resulted higher than that obtained for NiWP/gamma-Al2O3 catalyst. Even when both materials showed almost the same specific hydrogenation rate, the main change was the higher hydrogenolysis on the NiW/Al-nR catalyst. Theoretical calculations showed that 1T-S-W-S cluster with Ni on the top resulted with less metallic character than when Ni was modeled in a corner of a 2H-S-W-S 3D crystal. For that reason, it was proposed that Ni-W-S sites on small slabs could act rather as hydrogenolysis sites than as hydrogenation sites. (c) 2014 Elsevier Inc. All rights reserved.