Impact of diverse active sites on MoS2 catalyst: Competition on active site formation and selectivity of thiophene hydrodesulfurization reaction
Impact of diverse active sites on MoS2 catalyst: Competition on active site formation and selectivity of thiophene hydrodesulfurization reaction
复制标题
不同活性位点对MoS2催化剂的影响：活性位点形成的竞争和噻吩加氢脱硫反应的选择性
DOI：
10.1016/j.mcat.2018.11.014
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发表时间：
2019-02-01
影响因子：
4.6
通讯作者：
Wu, Chi-Man Lawrence
中科院分区：
文献类型：
--
作者：
Guo, Chen;Zhang, Tian;Wu, Chi-Man Lawrence
MoS 2是一种广泛应用于加氢脱硫（HDS）反应的高效催化剂。缺陷MoS 2簇上的配位不饱和活性位点（CUS）是HDS反应最活跃的位置。本研究利用密度泛函理论研究了MoS 2纳米团簇上不同活性位点的CUS形成竞争和噻吩HDS反应机理。首先，我们构建了五个有缺陷的MoS 2集群与不同的BOS。计算的形成能和吉布斯自由能表明，单角或单棱的MoS 2团簇是HDS条件下的有利结构，尤其是单角或单棱的MoS 2团簇。随后，噻吩吸附构型和HDS反应在角落和边缘的MoS（2）团簇上的解释。结果表明，角位CUS比边位CUS更有利于噻吩的吸附，这是因为角位CUS的空间位阻效应较小。对于在拐角CUS处的HDS工艺，通过加氢路线的反应更具竞争力，并且反应形成作为产物的2-丁烯和作为杂质的四氢噻吩。相比之下，在边缘CUS，丁二烯生产的直接脱硫路线在能量上更有利，表明增强的催化HDS性能。本工作为工业加氢脱硫过程中催化剂活性中心和催化反应产物的筛选提供了理论依据。
MoS2 is an efficient catalyst widely used in hydrodesulfurization (HDS) reaction. Coordinatively unsaturated active sites (CUS) on defective MoS2 clusters are the most active positions for HDS reaction. In this study, we investigated CUS formation competition and thiophene HDS reaction mechanism at diverse active sites on MoS2 nanoclusters by using density functional theory. First, we constructed five defective MoS2 clusters with different CUSs. The calculated formation energies and Gibbs free energies of these CUSs indicated that the MoS2 clusters with single-corner or -edge CUSs were the favorable structures under HDS condition, especially the former type. Subsequently, thiophene adsorption configurations and HDS reactions at the corner and edge CUSs on MoS(2 )clusters were elucidated. Results showed that the corner CUS was more beneficial for thiophene adsorption than the edge CUS due to the smaller steric hindrance effect. For HDS process at the corner CUS, reaction via hydrogenation route was more competitive, and the reaction formed 2-butene as a product and tetra-hydrothiophene as an impurity. By contrast, at the edge CUS, the direct desulfurization route with butadiene production was more energetically favorable, indicating an enhanced catalytic HDS property. This work provides theoretical basis in screening catalyst active sites and catalytic reaction products in industrial HDS processes.