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针对常规实验方法对硫化物加氢脱硫机理研究存在的不足,本文研究中运用分子模拟方法,建立了较为合理的MoS_2簇结构模型,在此基础上对MoS_2上几种主要活性位的加氢脱硫反应进行了比较系统的量子化学计算。计算结果表明,在噻吩加氢脱硫的过程中,Mo边和角位主要起加氢作用,主要生成2,5-二氢噻吩;而S边空位是主要的脱硫活性位,不仅接收Mo边和角位转移来的二氢噻吩并按加氢途径(HYD)脱硫,还可以吸附噻吩分子按直接脱硫途径(DDS)脱硫。但是1-己烯在三种活性中心上都可以发生加氢饱和反应。因此,对于MoS_2活性相而言,适当减少Mo边和角位的比例、增加S边的比例将有助于加氢脱硫活性和选择性的提高。
Aiming at the shortcomings of conventional experimental methods in the study of sulfidation hydrodesulfurization mechanism, a more reasonable model of MoS_2 cluster structure was established by using molecular simulation method in this study. Based on this, the hydrodesulfurization of several main active sites on MoS_2 was studied. The reaction proceeded with a relatively systematic quantum chemistry calculation. The calculated results show that during the hydrodesulfurization of thiophene, the Mo side and the angular position mainly play the role of hydrogenation, mainly generating 2,5-dihydrothiophene. The S-side vacancy is the main active site for desulfurization, which not only receives Mo edge and The dihydrothiophene transferred from the angle is desulfurized by hydrogenation (HYD), and the adsorbed thiophene can be desulfurized by the direct desulfurization (DDS). However, 1-hexene can undergo a hydrogenation saturation reaction on all three active sites. Therefore, for the active phase of MoS_2, it is helpful to increase the hydrodesulfurization activity and selectivity by properly reducing the ratio of Mo edge to the angular position and increasing the ratio of S edge.