Pathways for H<sub>2</sub> Activation on (Ni)-MoS<sub>2</sub> Catalysts
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Abstract
The activation of H<sub>2</sub> and
H<sub>2</sub>S on (Ni)MoS<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> leads
to the formation of SH
groups with acid character able to protonate 2,6-dimethylpyridine.
The variation in concentrations of SH groups induced by H<sub>2</sub> and H<sub>2</sub>S adsorption shows that both molecules dissociate
on coordinatively unsaturated cations and neighboring S<sup>2–</sup>. In the studied materials, one sulfur vacancy and four SH groups
per 10 metal atoms exist at the active edges of MoS<sub>2</sub> under
the conditions studied. H<sub>2</sub>–D<sub>2</sub> exchange
studies show that Ni increases the concentration of active surface
hydrogen by up to 30% at the optimum Ni loading, by increasing the
concentration of H<sub>2</sub> and H<sub>2</sub>S chemisorption sites