The effects of stepped sites and ruthenium adatom decoration on methanol dehydrogenation over platinum-based catalyst surfaces
The effects of stepped sites and ruthenium adatom decoration on methanol dehydrogenation over platinum-based catalyst surfaces
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DOI：
10.1016/j.cattod.2014.08.012
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发表时间：
2015-03
期刊：
影响因子：
5.3
通讯作者：
B. Y. Liu;J. Jin;X. Lin;C. Hardacre;P. Hu;Chun’an Ma;Wen-Feng Lin
中科院分区：
文献类型：
--
作者：
B. Y. Liu;J. Jin;X. Lin;C. Hardacre;P. Hu;Chun’an Ma;Wen-Feng Lin
采用密度泛函理论（DFT）研究了Pt基催化剂上甲醇脱氢反应在Pt（2 1 1）台阶表面上的催化行为.研究了CH 3OH脱氢的两种主要途径：由O-H键断裂形成甲氧基（CH 3 O）中间体，随后C-H键连续断裂成CO引发的O-H途径，C-H途径是由C-H键断裂形成羟甲基（CH_2 OH），然后两次C-H键断裂形成COH，然后是CO。还计算了H途径。与平坦的Pt（1 1 1）相比，阶梯状的Pt（2 1 1）增加了中间体的吸附能，除了在第一氢断裂中之外，对降低所涉及的大多数基本步骤的反应势垒没有显著贡献。然而，在Ru改性的表面上，发现C-H键断裂的第一步的反应势垒显著降低，并且许多进一步的脱氢步骤跨越到O-H途径，其中最容易的途径被确定。我们的数据揭示了甲醇催化反应过程在原子水平上的复杂性，并有助于对Pt基催化剂上燃料反应的基本理解。
A density functional theory study of methanol dehydrogenation over stepped Pt(2 1 1) surfaces without and with Ru modification was carried out to understand fuel catalytic reactions on Pt-based catalysts. Two main pathways of the CH3OH dehydrogenation were examined: the O–H pathway which was initiated by O–H bond scission to form the methoxy (CH3O) intermediate followed by sequential cleavage of C–H bonds to CO, and the C–H pathway which was initiated by C–H bond scission to form the hydroxymethyl (CH2OH) followed by two C–H bond cleavages to COH and then CO. Possible crossover reactions between the O–H and C–H pathways were also computed. Compared to flat Pt(1 1 1), stepped Pt(2 1 1) increases the adsorption energies of intermediates, making no significant contribution to decreasing the reaction barriers of most elementary steps involved, except in the first hydrogen scission. However, on the Ru-modified surface, a significant reduction was found in reaction barriers for the first step of the C–H bond scission and a number of further dehydrogenation steps crossing over to the O–H pathway, with the most facile paths identified. Our data reveals the complexity of methanol catalytic reaction processes at the atomic level and contributes to a fundamental understanding of fuel reactions on Pt-based catalysts.