%0 Journal Article %T Hydrogenolysis and β–elimination mechanisms for C S bond scission of dibenzothiophene on CoMoS edge sites %+ IFP Energies nouvelles (IFPEN) %+ Laboratoire de Chimie - UMR5182 (LC) %A Dumon, Alexandre %A Sahu, Amit %A Raybaud, Pascal %< avec comité de lecture %@ 0021-9517 %J Journal of Catalysis %I Elsevier %V 403 %P 32-42 %8 2021-11 %D 2021 %R 10.1016/j.jcat.2021.01.030 %K hydrodesulfurization %K dibenzothiophene %K hydrogenolysis %K beta-elimination %K CoMoS %K edge sites %K density functional theory %Z Chemical Sciences %Z Chemical Sciences/CatalysisJournal articles %X Unraveling the mechanisms of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and the corresponding active sites represents a scientific challenge to improve the intrinsic performances of Co-promoted MoS2 (CoMoS) catalysts. By using density functional theory calculations, we compare two historical mechanisms for the Csingle bondS bond scission of DBT (direct desulfurization): direct hydrogenolysis of DBT and β–elimination of α,β–dihydro-diobenzothiophene (α,β–DHDBT) on four relevant sites of the two CoMoS M- and S-edges. On the Co promoted M-edge, the α,β–DHDBT is formed through dihydrogenation which is kinetically competing with hydrogenolysis (both exhibiting activation free energies, ΔG‡, smaller than +1.24 eV). On the S-edge, both dihydrogenation and hydrogenolysis exhibit higher ΔG‡ (>+1.78 eV). Interestingly, on the S-edge, the β–elimination (E2 type) on the α,β–DHDBT is found to be kinetically competing (ΔG‡ = +1.14 eV). The elimination of Hβ atom involves a S2 dimer close to the S-vacancy site where DHDBT is adsorbed. Since this leaving Hβ atom is distinct from the one added at dihydrogenation step, this may explain why direct desulfurization of 4,6-alkyl substituted DBT compounds is hampered according to the elimination mechanism. We finally discuss the possible synergy between the two edges of CoMoS for HDS of DBT. %G English %2 https://ifp.hal.science/hal-03596645/document %2 https://ifp.hal.science/hal-03596645/file/Manuscript-DBT.pdf %L hal-03596645 %U https://ifp.hal.science/hal-03596645 %~ ENS-LYON %~ IFP %~ CNRS %~ UNIV-LYON1 %~ HAL-CHIMIE-ENSLYON %~ INC-CNRS %~ UDL %~ UNIV-LYON %~ ANR