摘要
采用共浸渍法制备了Fe-Mo／ZSM-5样品，并分别利用NO-TPD和暂态响应技术研究了NO的吸附性能。结果表明，NH。的存在不但能够大大减弱NO的吸附，而且使得催化剂表面NO的吸附位性质发生了改变，340℃左右的脱附峰可能对应于反应的活性位，并且其可能是与吸附氧有关的酸性吸附位。而O2的存在对NO吸附起着重要作用，吸附氧可能参与了NO的吸附过程。在反应条件下Fe-Mo／ZSM-5催化剂上可能有两种不同的NO吸附位存在，一种是没有吸附氧的吸附位，而另一种是与吸附氧有关的吸附位。在O2存在条件下，催化剂表面吸附态NO直接与毗邻的吸附态NH3物种作用形成N2和H2O。气相O2的作用是补充催化剂表面氧物种，使NO，氧化还原反应能够持续进行。
The Fe-Mo/ZSM-5 catalyst was prepared by co-impregnation method, and the properties of NO adsorption were studied by NO-TPD and Step-response techniques, respectively. The results showed that the adsorbed NH3 species restraied NO from adsorption, due to its strong competition ability to be adsorbed on the surface, as well as the properties of NO adsorption being changed greatly. The peak of 340℃, assigned to the acid site combined with adsorbed oxygen on the surface, may be related to the active site of SCR reaction. The presence of O2 obviously enhanced the NO adsorption on the surface of Fe-Mo/ZSM-5, the reason for which is the activity increase of some surface sites during the co-adsorption of O2 and NO, and the adsorbed oxygen may take part in the process of NO adsorption. It can be presumed that there are at least two types of adsorption sites on the surface, one is with adsorbed oxygen and another is without. It was also found that there were no gaseous NO2 detected during the whole adsorption/desorption process, which means that adsorbed NO species may be related to the active intermediate of SCR reaction, and can directly react with adjacent NH3 species on the surface to form N2 and HzO. And the role of gaseous O2in SCR reaction is to add the adsorbed oxygen species on the surface.
出处
《石油学报（石油加工）》
EI
CAS
CSCD
北大核心
2008年第B10期96-101,共6页
Acta Petrolei Sinica(Petroleum Processing Section)
