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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (10): 1264-1268. 上一篇    下一篇

研究简报

NOx/CO2/H2O在BaO(001)表面吸附的理论研究

吕乃霞*,1, 徐昕2   

  1. (1莱芜职业技术学院 莱芜 271100)
    (2厦门大学化学化工学院 厦门 361005)
  • 投稿日期:2010-08-28 修回日期:2011-01-18 发布日期:2011-01-24
  • 通讯作者: 吕乃霞 E-mail:xiaoxia791102@163.com
  • 基金资助:

    表面吸附的基础理论研究

Theoretical Study of NOx/CO2/H2O Adsorption on BaO(001) Surface

Naixia*,1,Xu Xin2   

  1. (1 Laiwu Vocational and Technical College, Laiwu 271100)
    (2 College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005)
  • Received:2010-08-28 Revised:2011-01-18 Published:2011-01-24
  • Contact: Nai-Xia LV E-mail:xiaoxia791102@163.com

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采用密度泛函理论(DFT)研究了NOx/CO2/H2O在BaO(001)表面不同覆盖度下的吸附情况. 计算表明NO以N端吸附在表面氧位, 形成 吸附物种|CO2以C端吸附在表面氧位, 形成表面 |而H2O在表面发生解离吸附, 导致BaO表面的羟基化. NO2有两种主要的吸附模式: 以N端吸附在表面氧位, 或以O端吸附表面Ba位. 各物种在表面的吸附顺序为: NO≈H2O＜CO2＜NO2, 并且随着覆盖度增加吸附能呈线性递减趋势. 值得注意的是, 两分子NO2在表面同时吸附存在显著的协同效应, 形成稳定的 / 吸附物种, 这种共吸附作用可能是BaCO3, Ba(OH)2分解最终形成表面 Ba(NO3)2的主要驱动力.

关键词: 稀燃, NSR 催化剂, DFT, NOx吸附, BaO(001)

Density functional theory (DFT) are used to carry out the trends in the adsorption chemistry of NOx (x＝1, 2), CO2, H2O on the BaO(001) surface. NO adsorbs on the surface O atom in the formation of species|CO2 is adsorbed on the surface O via its C atom and a carbonate-type structure is identified|while for the H2O adsorption, it is observed that H2O adsorbs dissociatively, forming hydroxyl on the surface|as for the adsorption structures of NO2, two important geometries are identified: one is N-bonded adsorbate, and the other is O-bonded adsorbate. The adsorption strength increases in the order NO≈H2O＜CO2＜NO2. For all adsorption species, the adsorption energies are markedly descending as the surface coverage increasing. It is worth noting that the simultaneous formation of surface / pairs by adsorptions of two NO2 is most energetically favorable, and the cooperation effect probably could be the driving force for the BaCO3 and Ba(OH)2 eventual conversion into Ba(NO3)2.

Key words: lean-burn, NSR catalyst, density functional theory (DFT), NOx adsorption, BaO(001)

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