LI Huailei1, LI Qiang2, DING Yong3, ZHANG Xiaotong1, LING Mingli1, SUN Zhaolin1, SONG Lijuan1
(1. Liaoning Key Laboratory of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001, Liaoning Province, P.R. China; 2. College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, P.R. China; 3. School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu Province, P.R. China)
Abstract: Adsorption properties of thiophene (TP) and alkylthiophene (2-methylthiophene (2-MT), 3-methylthiophene (3-MT), 2,3-dimethylthiophene (2,3-DMT), 2,4-dimethylthiophene (2,4-DMT), 2,5-dimethylthiophene (2,5-DMT) and 3,4-dimethylthiophene (3,4-DMT))on a MoS2 catalyst for hydrogenation desulfurization (HDS) have been Investigated by the first-principle DFT calculations which were based on a Mo16S32 cluster model and performed with PW91 function and DNP basis set. The calculated interaction energies indicate that the adsorption ability of the Mo16S32 cluster for the alkylthiophene molecules in η1S adsorption mode decreases in the order of 2,5-DMT＞2,4-DMT≈2,3-DMT＞2-MT＞3,4-DMT＞3-MT＞TP. According to the bond length, Mayer bond orders and Mulliken charge analysis, the adsorption energies are consistent with the electron density of the sulfur atom for the thiophenic compounds without any substituent in 2- and 5-positions. When 2- or 5- position is replaced by a methyl group, a weak interaction can be found between the methyl and the adjacent Mo atom and the adsorption energies increase compared with above sulfur compounds. For 2,5-DMT in which both 2- and 5- positions are substituted, the distance between the methyl groups and the adjacent Mo atom enlarges, leading weak interactions between them, The adsorption energy of 2,5-DMT on the Mo16S32 cluster does not increase as much as those for 2,4-DMT and 2,3-DMT molecules. The HDS reactions of all the sulfur compounds on the catalyst are also discussed in this paper.
Key words: alkylthiophene; HDS; adsorption; DFT; Mo16S32 cluster
E-mail: lsong@lnpu.edu.cn
Journal of Molecular Catalysis, Vol. 26, Issue 1, 2012, 62-69
