An ab Initio Molecular Orbital Study of the Hydrogen Sorbed Site in Co/MoS2Catalysts

A cluster model quantum chemical approach is used to study the electronic structure of Co in bimetallic sulfide catalysts Co/MoS 2 . The oxidative addition of hydrogen to the Co−Mo component is considered. Ab initio HF/MP2 and DFT calculations show that hydrogen occluded in the catalyst bulk is sorbed on the cobalt ion and stabilizes the Co(III) d 6 electronic state of cobalt ions in the sulfide catalysts. This electronic state is rather active, when surface sites interact with the S-containing reagents participating in the HDS catalysis. A model of active sites on the Co/MoS 2 catalyst is used to discuss the suggested molecular mechanism of the HDS catalysis.