Sulphide catalysts on silica as a support. III. x-ray photoelectron spectroscopy study

Superficial characterization and hydroconversion of tetralin over NiW sulfide catalysts supported on zirconium doped mesoporous silica

“…after sulfidation at 673 K, nickel is sulfided and interacts with W 2 S-like slabs covering all the edges. In fact, this BE is very close to those reported for this species on silica and alumina NiW supported catalysts [47,49]. It is noteworthy that Ni(5)W exhibits the maximum superficial concentration of W(IV) and the least of Ni 2+ as spinel, which means that the more sulfidable precursor is that with the maximum content of the dispersed NiWO 4 phase.…”

“…The precursors of both catalysts also exhibited the highest content of nickel as a NiWO 4 phase, as deduced from XPS analysis (Table 1) and from the I(845 cm −1 )/I(935 cm −1 ) ratio in the IR study. According to the literature the sulfidation at 673-773 K of nickel ions surrounding the W(VI) species leads to the formation of the so-called NiSW phase [46,47]. Thus, both catalysts derived from precursors with a higher amount of nickel as a NiWO 4 spinel exhibit a major degree of sulfidation.…”

Performance of NiMoS/Al2O3 prepared by sonochemical and chemical vapor deposition methods in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

“…It was previously reported that the binding energy of Ni increased when Ni formed mixed sulfide species with Mo, the so-called Ni-Mo-S phase, and when these species were in a highly dispersed state. 9,10 The shift in the binding energy by 0.6 eV for Ni(c)Mo(i) indicates that Ni added by CVD interacts more efficiently with the MoS 2 than when added by impregnation, which means that a larger amount of Ni-Mo-S species are produced in the former case. This is supported by the results of catalyst surface analyses (Table 2), which show that the ratio in the amounts of surface Ni to those of the total added Ni was higher for Ni(c)Mo(i) than for Ni(i)Mo(i).…”

Chelate complex Ni(S2C2H2)2 as a molecular model of the hydrodesulfurization active center

“…Ni(II) is the only common oxidation state of nickel, though its chemistry is known to span all oxidation states from -1 to +4 [6]. In this oxidation state, Ni has a d g electron configuration and forms a six-coordinate ion with octahedral symmetry and a paramagnetic (hg6,egl,eg l) ground state with weak-field ligands such as H20.…”