Ti-modified alumina supports prepared by sol–gel method used for deep HDS catalysts

Abstract

The typical physico-chemical properties and their hydrodesulfurization activities of NiMo/TiO 2-Al 2O 3 series catalysts with different TiO 2 loadings were studied. The catalysts were evaluated with a blend of two kinds of commercially available diesels in a micro-reactor unit. Many techniques including N 2-adsorption, UV–vis DRS, XRD, FT-Raman, TPR, pyridine FT-IR and DRIFT were used to characterize the surface and structural properties of TiO 2-Al 2O 3 binary oxide supports and the NiMo/TiO 2-Al 2O 3 catalysts. The samples prepared by sol–gel method possessed large specific surface areas, pore volumes and large average pore sizes that were suitable for the high dispersion of nickel and molybdenum active components. UV–vis DRS, XRD and FT-Raman results indicated that the presence of anatase TiO 2 species facilitated the formation of coordinatively unsaturated sites (CUS) or sulfur vacancies, and also promoted high dispersion of Mo active phase on the catalyst surfaces. DRIFT spectra of NO adsorbed on the pure MoS 2 and the catalysts with TiO 2 loadings of 15 and 30% showed that NiMo/TiO 2-Al 2O 3 catalysts possessed more CUS than that of pure MoS 2. HDS efficiencies and the above characterization results confirmed that the incorporation of TiO 2 into Al 2O 3 could adjust the interaction between support and active metals, enhanced the reducibility of molybdenum and thus resulted in the high activity of HDS reaction.