加氢脱硫反应分子在MoS_2表面吸附的分子模拟研究

Molecular simulation of reactant molecules adsorption on MoS_2 surface in hydrodesulfurization process

采用DFT计算的方法研究了加氢脱硫反应的模型化合物噻吩和1-己烯在S边空位、Mo边和角位上的吸附能,并分析该过程中的电荷转移和C—S及C=C键键长变化情况。计算结果表明:噻吩和1-己烯在3种活性中心上吸附的强弱趋势是一致的,都是角位最强,S空位其次,最弱是Mo边,同时,对于3种活性中心噻吩和1-己烯在各活性中心上的吸附能相差很小,即3种活性中心上噻吩和1-己烯的吸附选择性都很小。噻吩加氢后各中间产物在活性中心上的吸附显著增强,并且表现出了明显的选择性。此时吸附强弱大致顺序为S空位>角位>Mo边。

DFT calculation were used in this paper to study adsorption energy of the model compounds thiophene and 1-hexene on S vacancy at S edge, Mo edge and comer site in hydrodesulfurization process. After a comprehensive analysis of Charge-Transfer and the change of reactant bond length in HDS processing on MoS2, it could be concluded that the trend of the adsorption on thiophene and 1-hexene on active centers is consistent. The adsorption on comer site is the strongest, the second is S vacancy at S edge, and Mo edge is the weakest. In the meantime, there is little difference between the adsorption energy of thiophene and 1-Hexene. The adsorption selec- tivity of thiophene and 1-hexene on the active centers is very small. The adsorption of intermediate products of thiophene hydrogenation on the active center was significantly enhanced, and showed a significant selectivity. At this time the strength order of adsorption is S vacancy at S edge 〉 comer site 〉 Mo edge.