高等学校化学学报

高等学校化学学报 ›› 1997, Vol. 18 ›› Issue (7): 1153.

• 论文 • 上一篇    下一篇

Rh(100)表面乙醇吸附与分解的HREELS研究

田志坚1, 魏绪明2, 翟润生2, 任素贞2, 梁东白1, 林励吾1   

  1. 1. 中国科学院大连化学物理研究所, 大连 116023;
    2. 中国科学院催化基础国家重点实验室, 大连
  • 收稿日期:1997-02-03 出版日期:1997-07-24 发布日期:1997-07-24
  • 通讯作者: 林励吾.
  • 作者简介:田志坚, 男, 27岁, 博士, 助理研究员.
  • 基金资助:

    国家自然科学基金

HREELS Studies of Ethanol Adsorption and Decomposition on Rh(100) Surface

TIAN Zhi-Jian1, WEI Xu-Ming2, ZHAI Run-Sheng2, REN Su-Zhen2, LIANG Dong-Bai1, LIN Li-Wu1   

  1. 1. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023;
    2. State Key Laboratory of Catalysist, Chinese Academy of Sciences, Dalian 116023
  • Received:1997-02-03 Online:1997-07-24 Published:1997-07-24

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被引次数

6

摘要： 利用热脱附谱和高分辨能量损失谱技术研究了乙醇在Rh(100)表面的吸附和分解过程. 结果表明,130K时Rh(100)面暴露乙醇,表面首先形成化学吸附层,随乙醇暴露量增加,表面出现多层凝聚态. 表面升温至150K,吸附乙醇从Rh(100)表面脱附,同时部分化学吸附乙醇分子发生羟基断裂,生成表面乙氧基,进一步升温,表面乙氧基脱氢分解,其分解的主要途径是发生甲基脱氢,β-C与表面发生作用,生成一种含氧的金属有机环状中间体. 该表面中间体继续脱氢并同时发生C－C键断裂,表面生成CO和CHx物种;α－H断裂则是表面乙氧基分解的次要途径,其转变为表面乙醛中间体,乙醇中间体在进一步脱氢前发生C－C键断裂,分解为CO和CH3(在表面加氢生成CH4)脱附.

关键词: 乙醇吸附与分解, Rh(100), 高分辨能量损失谱, 热脱附谱, 含氧金属有机环状中间体

Abstract: The adsorption and decomposition of ethanol on the clean Rh (100) surface werestudied using thermal desorption spectroscopy(TDS) and high resolution electron energy lossspectroscopy (HREELS).At 130 K, on Rh (100) surface, the adsorption started from achemisorbed ethanol structure which was bonded to the surface through both Oand Hmoi-eties, with the O-Hbond almost parallel to the surfaces.Additional condensed phase of ad-sorbed ethanol was found to exist through hydrogen bonding.At about 150 K, the multilay-er-adsorbed ethanol desorbed from the surfaces, while the remaining chemisorbed ethanolcompletely converted to an ethoxy species via the first decomposition step in which O-Hbond scission occurred.The small amount of methane formed indicated that the dehydro-genation of the ethoxide intermediates on the clean Rh(100) surface was non-selective.Lossof hydrogen from the methylene group would result in the formation of an aldehyde interme-diate.Decarbonylation of the aldehyde intermediates produced methane and CO.This path-way appeared to be a minor one for ethoxide decomposition on Rh(100).The main ethoxidedehydrogenation proceeded via the cleavage of a C-Hbond on the methyl group, resultingin the formation of an oxametallocyclic intermediate.The loss spectra at 629 cm-1 is as-signed to this intermediate.The C-Cbond scission occurred at the same time in the oxamet-allocyclic dehydrogenation sequence.Then the COand hydrocarbon moieties were formed onthe surface.

Key words: Adsorption and decomposition of ethanol, Rh (100), High resolution electron en-ergy loss spectroscopy, Thermal desorption spectroscopy, Oxametallocyclic intermediate

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