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Abstract: The catalytic hydrodesulfurization (HDS) reactions of COS and CS2 with Mo3S9 cluster have been systematically investigated as a part of HDS of industrial feedstocks by DFT-based method. A detailed description of mechanisms is given, and different pathways are discussed and compared. It is found that the S in COS and CS2 will be hydrogenated, and the reactions will lead to formations of H2S, CO and CS. Comparing with COS, CS2 reacts with lower activation free energy and shows more reaction activity. [Copyright &y& Elsevier]

Abstract: The reaction mechanism of thiophene hydrodesulfurization (HDS) on a Mo3S9 model catalyst has been investigated at the GGA level of density functional theory. On the basis of the computed energetic data, 2,5-dihydrothiophene has been identified as the most important intermediate of HDS processes, and it is responsible for the direct formation of butadiene as the principal product. Neither the stepwise formation of cis-2-butene nor that of butane is competitive. However, butene (or butane) can be obtained from the hydrogenation of the formed butadiene. [Copyright &y& Elsevier]

Abstract: The entire catalytic hydrodesulfurization (HDS) cycle of benzothiophene over Mo3S9 cluster has been investigated at the level of density functional theory. It is found that the hydrogenation and hydrogenolysis route with dihydrobenzothiophene (DHBT) as intermediate is more favored than the hydrogenolysis and hydrogenation route with styrene as intermediate. The stepwise hydrogenolysis of SB–C9 (C(aryl)–S) bond in DHBT leading to the formation of 2-phenylethanethiol is more favored than that of SB–C2 (C(alkyl)–S) bond with 2-ethylthiophenol as intermediate. The computed activation free energy and rate constant of benzothiophene hydrogenation to DHBT agree well with the available experimental data. The difference in HDS reactivity between benzothiophene and thiophene has been discussed. [Copyright &y& Elsevier]