Study of the Hydrogen Activation Reaction on Nanosized MoS2 Particles under Hydroconversion Conditions

Resumo

The mechanism of activation of a hydrogen molecule upon interaction with the surface of nanosized particles of the MoS₂ hydroconversion catalyst has been modeled using a quantum-chemical method of the density functional theory (DFT) with the hybrid functional B3LYP/dgdzvp in the cluster approximation. Two clusters, Mo₂S₄ and Mo₃S₆, have been considered as structural models of nanosized catalyst particles. It has been shown that the primary event of interaction of molecular H₂ with the catalyst surface is the chemisorption of hydrogen atoms on the molybdenum atom with H–H bond breaking. The local minima of the total electronic energy of the complexes in the chemisorption of hydrogen atoms on Mo and S atoms and the energy of the transition state between local minima have been found. It has been established that the stability of the complexes [Mo₃S₆…H₂] varies in the order: [···MoH₂] > [(S)H···(S)H] > [(Mo)H···(S)H] > [(Mo)H···(Mo)H] > [···SH₂].