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运用密度泛函理论(DFT),采用Mo16S32团簇模型,在PW91/DNP水平上研究了噻吩(TP)及一系列烷基噻吩类硫化物如2-甲基噻吩(2-MT)、3-甲基噻吩(3-MT)、2,3-二甲基噻吩(2,3-DMT)、2,4-二甲基噻吩(2,4-DMT)、2,5-二甲基噻吩(2,5-DMT)及3,4-二甲基噻吩(3,4-DMT)等在加氢脱硫催化剂MoS2上的吸附行为.结果表明,在η1S吸附构型中,Mo16S32团簇对烷基噻吩吸附能力的顺序为2,5-DMT>2,4-DMT≈2,3-DMT>2-MT>3,4-DMT>3-MT>TP.通过键长、Mayer键级、Mulliken电荷分析可知,当噻吩环的2-或5-位不含甲基时,吸附能随硫原子电荷密度的增加而增大;2-或5-位含甲基时,甲基与团簇上相邻的Mo原子发生了弱的相互作用,使吸附能增大;虽然2,5-DMT的2-和5-位均含有甲基,但甲基离团簇上相邻的Mo较远,相互作用较小,吸附能较2,3-DMT和2,4-DMT增加的较少.文中还对各硫化物在MoS2催化剂上的加氢脱硫反应进行了讨论.
Thiophene (TP) and a series of alkylthiophene sulfides such as 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 the hydrodesulfurization catalyst MoS2.The results show that in the η1S adsorption configuration, the molar ratio of Mo16S32 to alkyl The order of thiophene adsorption capacity is 2,5-DMT> 2,4-DMT ≈2,3-DMT> 2-MT> 3,4-DMT> 3-MT> The analysis shows that when the 2- or 5-position of the thiophene ring contains no methyl group, the adsorption energy increases with the increase of the charge density of the sulfur atom. When the 2- or 5-position contains the methyl group, Mo atoms near the weak interaction occurs, so that the adsorption energy increases; Although the 2,5-DMT 2- and 5-bit contain methyl groups, but the methyl group is far away from the adjacent Mo Mo, mutual The adsorption capacity is less than that of 2,3-DMT and 2,4-DMT.The hydrodesulfurization reaction of each sulfide on MoS2 catalyst is also discussed.