CIESC Journal ›› 2018, Vol. 69 ›› Issue (4): 1476-1483.DOI: 10.11949/j.issn.0438-1157.20170871

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Mechanisms of selective hydrogenation of crotonaldehyde on In/Au (111) and Ir/Au (111) surfaces

XIA Shengjie1, LUO Wei1, XUE Jilong1, MENG Yue1,2, JIANG Junhui1, NI Zheming1   

  1. 1. College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China;
    2. School of Life Sciences, Huzhou University, Huzhou 313000, Zhejiang, China
  • Received:2017-07-07 Revised:2017-09-23 Online:2018-04-05 Published:2018-04-05
  • Supported by:

    supported by the National Natural Science Foundation of China (21503188) and the Natural Science Foundation of Zhejiang Province (LQ15B030002).

In/Au(111)和Ir/Au(111)面上巴豆醛选择加氢的机理研究及比较

夏盛杰1, 罗伟1, 薛继龙1, 孟跃1,2, 蒋军辉1, 倪哲明1   

  1. 1. 浙江工业大学化学工程学院, 浙江 杭州 310014;
    2. 湖州师范学院生命科学学院, 浙江 湖州 313000
  • 通讯作者: 倪哲明
  • 基金资助:

    国家自然科学基金项目(21503188);浙江省自然科学基金项目(LQ15B030002)。

Abstract:

From stable structures of vertical crotonaldehyde (CAL) adsorption on alloy surfaces of M/Au (111) (M=In, Ir), reaction mechanisms of incomplete hydrogenation (C=O addition, C=C addition, and 1,4-conjugate addition) of CAL on the M/Au (111) surface were studied by density functional theory (DFT) in combination with periodic slab model. Calculation of activation energy and heat of elementary step reactions and analysis of conformation change at various hydrogenation mechanisms showed that CAL on the In/Au (111) and Ir/Au (111) planes first hydrogenated near-surface C=O by A2 mechanism, which an H atom was first added to active C on generation of MS1 and then another H atom was added to intermediate MS1. Both elementary reactions were exothermic but the first one was the rate-determining step due to higher activation energy. The maximum energy barrier of elementary reactions of CAL hydrogenation by the optimal hydrogenation mechanism on In/Au (111) surface was 0.969 eV, which was much lower than that of 1.332 eV on the Ir/Au (111) surface. Hence, In/Au (111) had better catalytic activity than Ir/Au (111) surface for incomplete hydrogenation of CAL. Adsorption of reactant and products on M/Au (111) surface indicated that formation of strong chemical adsorption between crotonaldehyde O atom and alloy doping element M improved selectivity of M/Au (111) to C=O hydrogenation.

Key words: DFT, crotonaldehyde, computational chemistry, hydrogenation, adsorption, In/Au (111), Ir/Au (111)

摘要:

基于巴豆醛在M/Au(111)合金表面(M=In,Ir)垂直吸附的最稳定吸附结构,采用密度泛函理论对其不完全加氢的反应机理进行探究。从不同加氢机理下各基元反应的活化能、反应热计算以及构型变化分析中可知,巴豆醛在M/Au(111)面上均优先对距离合金表面较近的C=O进行加氢,且以C为活性中心优先进行加氢为最优机理,其中第1步加氢反应的活化能较高,是该机理的控速步骤。反应物巴豆醛的O原子与合金的掺杂原子M形成较强的化学吸附,提高了M/Au(111)面对C=O加氢的选择性。巴豆醛按最优机理加氢的基元反应中在In/Au(111)面上最高反应能垒为0.969 eV,比在Ir/Au(111)面的最高反应能垒1.332 eV低,因此认为In/Au合金对其不完全加氢有更好的催化活性。

关键词: 密度泛函理论, 巴豆醛, 计算化学, 加氢, 吸附, In/Au (111), Ir/Au (111)

CLC Number: