化工学报 ›› 2014, Vol. 65 ›› Issue (10): 4056-4062.DOI: 10.3969/j.issn.0438-1157.2014.10.040

• 能源和环境工程 • 上一篇    下一篇

SCR反应过程中NO/NH3在γ-Al2O3表面吸附特性

曹蕃1, 苏胜1, 向军1, 王鹏鹰1, 胡松1, 孙路石1, 张安超2   

  1. 1 华中科技大学煤燃烧国家重点实验室, 湖北 武汉 430074;
    2 河南理工大学机械与动力工程学院, 河南 焦作 454000
  • 收稿日期:2014-03-20 修回日期:2014-05-27 出版日期:2014-10-05 发布日期:2014-10-05
  • 通讯作者: 苏胜
  • 基金资助:

    教育部科学技术研究项目(113045A);国家自然科学基金项目(51176062,51306046)。

NO/NH3 adsorption properties on γ-Al2O3 (110) surface during SCR process

CAO Fan1, SU Sheng1, XIANG Jun1, WANG Pengying1, HU Song1, SUN Lushi1, ZHANG Anchao2   

  1. 1 State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China;
    2 School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China
  • Received:2014-03-20 Revised:2014-05-27 Online:2014-10-05 Published:2014-10-05
  • Supported by:

    supported by the Foundation for Key Program of Ministry of Education (113045A) and the National Natural Science Foundation of China (51176062,51306046).

摘要: 采用密度泛函理论(DFT)方法研究了NO和NH3在完整和有缺陷的γ-Al2O3(110)表面吸附与SCR(选择催化还原)反应特性。研究表明,NO在完整的(110)表面的吸附作用较弱,而NH3分子的吸附作用较强,NH3分子在Al原子顶位可形成稳定吸附。反应路径研究结果表明完整的(110)表面上SCR反应的决速步为-NH2NO基团的分解,反应的最大能垒为235.75 kJ·mol-1。对于产生氧空穴的有缺陷(110)表面,NO和NH3均可稳定吸附,NH3在吸附过程中可直接裂解成NH2和H。另外,SCR反应在有缺陷(110)表面的最大能垒明显较低,说明氧空穴的存在促进了SCR脱硝反应的进行。

关键词: 氧化铝, 分子模拟, 吸附, 密度泛函, 一氧化氮

Abstract: γ-Al2O3 is an outstanding catalyst carrier and has been widely used in the SCR (selective catalytic reduction) catalyst study. The adsorption and reaction properties of NO/NH3 on the bare and defective γ-Al2O3 (110) surface were studied by the DFT (density functional theory) method. The corresponding microscopic parameters, such as adsorption energies, bond length, changes of net charge and PDOS (partial density of states) were calculated. NO could be adsorbed on the bare (110) surface weakly, and it was more inclined to be adsorbed on the top sites of O2c. NH3 could be adsorbed strongly on top sites of Al. The rate-determining step of SCR reaction was the -NH2NO decomposition, while the largest energy barrier reached 235.75 kJ·mol-1. For the defective (110) surface with the oxygen vacancy, NO and NH3 could be both adsorbed strongly on the surface, and NH3 could also decompose into NH2 and H directly in this situation. The largest energy barrier of SCR reaction in this situation was much lower, indicating that the presence of oxygen vacancy could promote SCR reaction proceeding.

Key words: alumina, molecular simulation, adsorption, density functional theory, nitric oxide

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