Relationships of Structural, Electronic and Energy Properties of Free and Adsorbed Molecules Over MoS2 Model Clusters, Involved in the DDS and HYDS Pathways for the HDS Of 4,6-DMDBT. A CDFT Study
Academic Article in Scopus
The reaction pathways, direct desulfurization (DDS) and hydrogenation-desulfurization (HYDS), in the HDS of 4,6-DMDBT on MoS2 clusters representing different models of coordinatively unsaturated sites (CUS) and brim active sites are analyzed using Density Functional Theory (DFT) and related concepts (CDFT). Reactivity indices of free molecule are related to the structural and energy properties of the chemisorbed molecules in model clusters. The results show that the bond lengths between the S atom of the adsorbed organic molecules and the Mo atom at CUS are multilinearly related to nucleophilic indices of nucleophilic centers of free molecules. In the DDS pathway, the high adsorption energy and the large S-Mo bond length of 3,3'-dimethyl-biphenyl-2-thiol suggest that the controlling reaction step is the hydrogenolysis of its S-C bond. It was found that a multilinear relationship exists between surface reaction energies (hydrogenation, hydrogen transfer, and hydrogenolysis) and reaction energies calculated for free molecules, electrophilicity global indices, and HOMO-LUMO gaps of free sulfur-containing molecules. Similarly, multilinear relationships were found between adsorption energies of the molecules on CUS and brim sites of model clusters and the nucleophilic indices of the different nucleophilic centers in free molecule.
