TEM and XPS studies of Ni/WS2 catalysts for thiophene hydrogenolysis

Hydrodesulfurization of sulfur refractory compounds: Effect of gallium as an additive in NiWS/γ-Al2O3 catalysts

“…8B). The obtained value for the NiS was fairly close to the ones reported in the literature [48][49][50][51][52][53].…”

Effects of pH and chelating agent on the NiWS phase formation in NiW/γ-Al2O3 HDS catalysts

“…Apparently, the electronegativity of the [Ni(CyDTA)] 2À complex has little effect on the binding energies separating satellite and main peaks of Ni 2p 3/2 spectra. The BE at 853.1 eV is close to value reported in literature for bulk NiS on unsupported WS 2 (852.9 eV) [36] whereas the BE at 854.4 eV is close to value reported for NiWS species formed after sulfidation of the NiW/g-Al 2 O 3 catalysts at 673 K [40,41].…”

“…11. Each Ni 2p 3/2 profile was resolved in three components at 853.1, 854.4 and 855.8 eV, corresponding to highly dispersed NiS [36], NiWS [32,37] and NiO x phases [32,37], respectively. Apparently, the electronegativity of the [Ni(CyDTA)] 2À complex has little effect on the binding energies separating satellite and main peaks of Ni 2p 3/2 spectra.…”

“…The observation of three well-resolved spin orbit split doublet peaks corresponding to W 4f 7/2 and W 4f 5/2 states indicates that there are three different W-species. The first doublet with W 4f 7/2 and W 4f 5/2 binding energy values at 32.3 and 34.4 eV, is assigned to WS 2 (W 4þ ) species [36,37] whereas the other two doublets at 34.9 and 37.1 eV, and at 35.7 and 37.8 eV are attributed to WO x S y (W 5þ ) and WO x (W 6þ ) species, respectively [38,39]. Table 1 reports the relative concentration for each species.…”

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

“…853.5 and 856.5 eV in the XP spectra, being assigned to sulfided nickel and nickel remaining as NiWO 4 , respectively. Taking into account that the BE for Ni 2+ ions in NiS is close to 852.9 eV [48], the value at 853.5 eV for Ni 2+ indicates that this part of the nickel is embedded in the WS 2 structure and probably forming the NiWS phase, i.e. after sulfidation at 673 K, nickel is sulfided and interacts with W 2 S-like slabs covering all the edges.…”