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Chemisorbed oxygen atom on the activation of C-H bond in methane: a Rh model study

机译:甲烷中C-H键活化的化学吸附氧原子:RH模型研究

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摘要

Single atom catalysts usually show unique catalytic activity and the physical nature is not clear. In the present work, density functional theory calculations are presented for adsorption and dissociation of CH4 on clean and oxygen atom pre-adsorbed Rh metal surfaces with different coordinate numbers such as (111), (100), (110), (211), kink, ad-row (add two atoms on a p(2 x 2)-111 unit cell) and ad-atom (add one atom on a p(2 x 2)-111 unit cell). The present calculation results show that the pre-adsorbed oxygen atom inhibits the methane dehydrogenation on Rh surfaces in general except on the ad-atom model where it has no effect, thus resulting in the possibility of the partial oxidation of methane to produce syngas (the mixture of CO and H-2) on Rh ad-atom catalysts. Having been analyzed by the barrier decomposition method, it was found that the presence of an oxygen atom usually reduces the adsorption energy of dissociated fragments and increases the interaction between the dissociated fragments, both of which lead to an increase of the reaction barrier. Moreover, the electronic analysis indicated that the oxygen effect can be attributed to the strong interaction of acid-base pair sites on oxygen-metal systems, and a strong acid-base interaction related to the low dehydrogenation barrier.
机译:单个原子催化剂通常显示出独特的催化活性,物理性质不明确。在本作工作中,介绍密度函数理论计算,用于在清洁和氧原子上的CH 4对CH 4的吸附和解离具有不同坐标数,例如(111),(100),(110),(211),扭结,ad-row(在ap(2 x 2)-111单元电池上添加两个原子)和ad-atom(在ap(2 x 2)-111单位单元上添加一个原子)。本计算结果表明,预吸附的氧原子通常抑制Rh表面上的甲烷脱氢,但除了施联的抗体模型,从而导致甲烷部分氧化的可能性产生合成气( CO和H-2的混合物)对rh Ad-原子催化剂。通过阻隔分解方法分析,发现氧原子的存在通常会降低离解碎片的吸附能量,并增加离解碎片之间的相互作用,这两者都导致反应屏障的增加。此外,电子分析表明氧效可归因于酸碱对氧 - 金属系统上的强相互作用,以及与低脱氢屏障有关的强酸碱相互作用。

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  • 来源
    《RSC Advances》 |2015年第81期|共10页
  • 作者单位

    Shandong Univ School Chem &

    Chem Engn Jinan 250100 Peoples R China;

    Shanxi Datong Univ Coll Chem &

    Envirom Engn Datong 037009 Shanxi Peoples R China;

    Nankai Univ Dept Chem Tianjin 300071 Peoples R China;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
  • 关键词

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