Distribution of Metal Cations in Ni‐Mo‐W Sulfide Catalysts

Abstract

The distribution of metal cations and the morphology of unsupported NiMo, NiW, and NiMoW sulfide catalysts were explored qualitatively and quantitatively. In the bi‐ and trimetallic catalysts, Mo(W)S2 nanoparticles are deposited on Ni sulfide particles of varying stoichiometry and sizes (crystalline Ni9S8, and Ni3S4 were identified). These nanoparticles are stacks of Mo(W)S2 slabs with varying size, degrees of bending and mismatch between the slabs. High resolution electron microscopy and X‐ray absorption spectroscopy based on particle modeling revealed a statistical distribution of Mo and W within individual layers in sulfide NiMoW, forming intralayer mixed Mo1−xWxS2. Ni is associated with MoS2, WS2, and Mo1−xWxS2 creating Ni‐promoted phases. The incorporation of Ni at the edges of the slabs was the highest for sulfide NiMoW. This high concentration of Ni in sulfide NiMoW, as well as its long bent Mo1−xWxS2 slabs, were paralleled by the highest activity for nitrogen and sulfur removal from model hydrocarbons such as o‐propylaniline and dibenzothiophene.

Towards Understanding Structure–Activity Relationships of Ni–Mo–W Sulfide Hydrotreating Catalysts

“…Some characterization results of bimetallic NiMo, NiW, and NiMoW2 sulfides have been reported in ref. . We complete these results and compare them with the characterization of NiWMo1 in the Supporting Information.…”

“…We have shown previously that in bulk Ni–Mo–W sulfide catalysts Mo and W cations are present in the same sulfide slabs, which might facilitate the formation of Ni‐promoted Mo 1− x W x S 2 species . The cause of this is explored in this work, which further studies the nature of the interactions of Mo 1− x W x S 2 species with the promoter Ni as well as how the precursor materials determine these interactions and influence catalysis.…”

“…The maxima in the radial distribution function (RDF) of the sulfides were more intense and the peaks shifted to higher distances compared to the oxide precursors owing to the stronger backscattering of S, and the covalent metal−S (M−S) bond character. We have presented a detailed analysis of the EXAFS of NiMo, NiW, and NiMoW2 previously and, therefore, we now focus on the comparison of the two trimetallic catalysts in relation to both bimetallic catalysts emphasizing the differences in structure.…”

“…The activity has been correlated with the replacement of Mo by Co or Ni at the edges of the MoS 2 phase . However, the local environment of metal cations and their relative locations in unsupported sulfides has only been studied incompletely . These studies indeed indicate that the structure and distribution of metal cations play an important role for the promotion effects in sulfide catalysts.…”

“…These studies indeed indicate that the structure and distribution of metal cations play an important role for the promotion effects in sulfide catalysts. The activity of such sulfides for hydrodenitrogenation (HDN) has been explored less extensively than for hydrodesulfurization (HDS) . Thus, the present paper aims to describe the structure of multimetallic Ni–Mo, Ni–W, and Ni–Mo–W oxide precursors and sulfide materials (focusing here on the interfacial Mo(W)–Ni interactions) and its consequences for hydrotreating during HDS and HDN.…”