Oxidative addition of dihydrogen as the key step of the active center formation in the HDS sulfide bimetallic catalysts: ab initio MO/MP2 study

MoS2 single slab as a model for active component of hydrodesulfuration catalyst: a quantum chemical study 1. Molecular and electronic structure of Mo12S24 macromolecule and its adsorption complex with H2S

“…These results substantiate the recom mendations reported earlier. 16 Molecular and electronic structure of adsorption com plex Mo 12 S 24 •6H 2 S. In order to characterize the adsorp tion ability (or Lewis acidity) of the coordinatively unsat urated Mo I centers, we carried out calculations of the adsorption complex of Mo 12 S 24 macromolecule with six H 2 S molecules to retain the MoS 2 single slab sym metry. The calculated band gap (energy difference be tween the highest occupied and lowest unoccupied MOs, ε i (HOMO) -ε i (LUMO)) equals 0.98 (0.85) eV.…”

The Reaction Mechanisms of H2S Decomposition into Hydrogen and Sulfur: Application of Classical and Biological Thermodynamics

“…The active component of the sulfide hydrodesulfurization (HDS) catalysts consists of a single slab of MoS 2 with Ni or Co atoms being located in its edge plane in the center of a square pyramid made of sulfur atoms (Figure 1). The active sites for H 2 S adsorption are Co(III) or Ni(IV) atoms in the d 6 electronic configuration (Figures 2 and 3) [13][14][15]. The essential element of the active component is hydrogen occluded into the MoS 2 matrix (Figures 1 and 3).…”

“…It localizes in the center of ''empty'' trigonal prism of a MoS 2 matrix made from six sulfur atoms under Ni (Co) atom at the distance of 1.5 Å (Figure 1). The active metal ions are oxidized by the occluded hydrogen to Co(III) and Ni(IV) and acquired d 6 electron configuration ( Figure 3) [13][14][15]. Two unoccupied orbitals of the active metal atom, 3d z2 and 3d xz interact effectively with the n σ and n π orbitals of the H 2 S molecule ( Figure 3).…”

Modelling hydrogen transport in molybdenum disulfide catalysts with muon spin relaxation spectroscopy

“…3 Molybdenum disulfide will uptake an amount of hydrogen which exceeds considerably a monolayer coverage. 7,16 Therefore, it is not necessarily surprising that MoS 2 acts more like a metal than a semiconductor such as GaAs. If the muons are sitting in the van der Waals gap, then they may be screened by the negative sulfur atoms.…”

“…6 The dissociation of H 2 on an NiMoS cluster has been examined by Hartree-Fock calculations at the MP2 level. 7 Dissociation of hydrogen proceeds by oxidative addition on the nickel atom resulting in the formation of surface hydrogen bound to nickel and sub-surface, occluded hydrogen within the trigonal sulfur prism of the MoS 2 unit cell. However, hydrogen is apparently not dissociated by bulk cobalt sulfide.…”