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首页> 外文期刊>Catalysis science & technology >Density functional theory study of thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni-55 cluster: implication for the mechanism of reactive adsorption desulfurization over Ni/ZnO catalysts
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Density functional theory study of thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni-55 cluster: implication for the mechanism of reactive adsorption desulfurization over Ni/ZnO catalysts

机译：密度泛函理论研究噻吩脱硫的脱硫和转换倪(111)表面的产品和Ni-55集群:机制的含义活性吸附脱硫在Ni /氧化锌催化剂

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摘要

Ni/ZnO catalysts have been well recognized by industry and academia for exhibiting excellent desulfurization activities. However, the intrinsic reaction mechanism on the Ni active center is still obscure. Herein, we performed periodic density functional theory (DFT) calculations to study thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni-55 cluster, and clarify the size effect of the Ni substrate and the essential role of hydrogen. The thiophene molecule binds more strongly to Ni-55 than Ni(111), and proceeds easily along the direct desulfurization pathway without prior hydrogenation on both Ni(111) and Ni-55. Ni-55 exhibits higher desulfurization activity while Ni(111) performs better in converting the remaining C4H4 species to butadiene and the deposited S atom to H2S. In contrast to the classic S transfer mechanism via H2S, we found that direct S diffusion occurs easily on the Ni substrate and has priority over its further hydrogenation to H2S, indicating that the S diffusion mechanism could play an important role in transferring surface S from Ni to ZnO. The results also show that the C-S bond rupture of thiophene and subsequent S removal from Ni tend to proceed without the assistance of hydrogen, and hydrogen mainly takes part in the hydrogenation of C4H4 species. The present work clearly demonstrates that the rate-determining step for thiophene desulfurization and subsequent alkene formation is the C4H4 hydrogenation rather than the cleavage of C-S bonds, in accordance with the experimental results.
机译：Ni /氧化锌催化剂已被认可表现出优秀的工业和学术界脱硫的活动。内在Ni活性反应机理中心仍然是模糊的。周期性的密度泛函理论(DFT)计算研究噻吩脱硫和脱硫产品的转换倪(111)表面和Ni-55集群,并澄清倪衬底和的尺寸效应氢的重要作用。分子结合Ni-55比更强烈倪(111),沿着直接收益很容易脱硫途径事先氢化镍(111)和Ni-55。展品更高的脱硫活性倪(111)在转换执行得更好剩余C4H4丁二烯和物种原子沉积年代硫化氢。经典的年代转移机制通过H2S,我们发现直接扩散容易发生在倪底物,并对其进一步的优先级加氢H2S,表明S扩散机制能发挥重要作用在氧化锌表面年代从倪转移。结果还表明,c键的断裂噻吩和随后的年代从倪往往删除继续没有氢的援助,和氢主要参加加氢C4H4物种。清楚地表明,速率决定一步噻吩脱硫和后续烯烃是C4H4加氢而形成根据c债券的乳沟与实验结果。

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