Influence of sulfur vacancy on thiophene hydrodesulfurization mechanism at different MoS2 edges: A DFT study
Influence of sulfur vacancy on thiophene hydrodesulfurization mechanism at different MoS2 edges: A DFT study
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不同MoS2边缘硫空位对噻吩加氢脱硫机理的影响：DFT研究
DOI：
10.1016/j.ces.2017.02.037
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发表时间：
2017
影响因子：
4.7
通讯作者：
Jiyuan Fan
中科院分区：
文献类型：
--
作者：
Peng Zheng;Aijun Duan;Kebin Chi;Liang Zhao;Chunyun Zhang;Chunming Xu;Zhen Zhao;Weiyu Song;Xilong Wang;Jiyuan Fan
通过密度泛函理论（DFT）计算研究了不同MoS2边缘结构的硫空位上噻吩的详细氢化（HYD）和直接脱硫（DDS）途径。通过色散校正方法（DFT + D）评估相互作用能。创新性地提出了硫空位上的详细噻吩加氢脱硫（HDS）反应网络，涉及实验中可以检测到的大部分产物。考虑到硫空位的影响，通过比较DDS和HYD途径的反应势垒可以发现，Mo边缘的硫空位更有利于DDS途径所含中间体和产物的形成。 HYD反应途径涉及氢化成2-氢噻吩，然后氢化成2,3-二氢噻吩和2,5-二氢噻吩，可以在S边缘处以温和的反应势垒进行，并产生硫空位。结果还表明，丁烷可以在 S 和 Mo 边缘形成，具有相对较高的反应势垒，分别为 52.60 kcal/mol（Mo-edge，DDS）、53.99 kcal/mol（S-edge，DDS）和 58.07 kcal/mol（Mo-edge，HYD），然而，1-丁烯和 2-丁烯的形成更有利于 1-丁烯和 2-丁烯的形成，其能量势垒为分别为 33.45 kcal/mol（S-edge HYD）和 35.20 kcal/mol（Mo-edge DDS）。这些结果表明MoS2催化剂不同边缘的硫空位对整个HDS反应路线有很大影响。基于系统计算，明确了硫空位对某些中间体和产物形成的贡献，为加氢脱硫技术设计高活性催化剂提供了理论指导。
The detailed hydrogenation (HYD) and direct desulfurization (DDS) pathways of thiophene over the sulfur vacancy of different MoS2edge structures were investigated by density functional theory (DFT) calculations. The interaction energies were evaluated by dispersion corrected methods (DFT + D). Innovatively, a detailed thiophene hydrodesulfurization (HDS) reaction network over the sulfur vacancy was proposed, involving most of products which could be detected in the experiments. Taking the influence of sulfur vacancy into consideration, it could be found that the sulfur vacancy at Mo-edge was more beneficial for the formation of intermediates and products contained in DDS pathway by comparing the reaction barriers of DDS and HYD pathways. The HYD reaction pathway, which involved hydrogenation to 2-hydrothiophene followed by hydrogenation to 2,3-dihydrothiophene and 2,5-dihydrothiophene, could proceed with a mild reaction barrier at the S-edge with the creation of sulfur vacancy. The results also showed that butane could be formed at both S and Mo edges with relatively high reaction barriers of 52.60 kcal/mol (Mo-edge, DDS), 53.99 kcal/mol (S-edge, DDS) and 58.07 kcal/mol (Mo-edge, HYD), however, the formations of 1-butene and 2-butene were much more favored with energy barriers of 33.45 kcal/mol (S-edge HYD) and 35.20 kcal/mol (Mo-edge DDS), respectively. These results demonstrated that the sulfur vacancy at the different edges of MoS2catalysts had a great impact on the overall HDS reaction routes. Based on the systematic calculations, the contribution of sulfur vacancy to the formation of certain intermediates and products was clearly orientated, which provided theoretical guidance for designing highly active catalysts for HDS technology.