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 O_2c. 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

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