用过渡应答技术研究V2O5-TiO2上NO-NH3选择性还原反应的机理
STUDIES ON THE SELECTIVE REDUCTION OF NO WITH NH3 OVER V2O5-TiO2 CATALYSTS BY TRANSIENT RESPONSE TECHNIQUE
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摘要: 在固定床、柱塞流反应器中,以浓度跃变方法进行过渡应答实验,研究了在V2O5-TiO2催化剂上,存在O2时NO与NH3进行的选择性还原反应.根据应答曲线提出了该过程的反应历程,认为:反应是在吸附态的NH3与NO物种之间进行的,其速率控制步骤是NO的吸附;催化剂表面Vs4+-OH再氧化为V5+=O所需要的氧,可以从气相、也可以从体相骨架中逐层获得,而从V2O5体相骨架传递氧到表面是通过一个“氧空穴”完成的.Abstract: The selective catalytic reduction of NO with NHa in the presence of O2 on TiO2-supported V2O5 have been studied with a fixed bed, plug flow reactor by the transient response technique of concentration step perturbation. A reaction mechanism based on the response curves of this study and those of others is proposed. The reaction involved adsorbed NH3 and NO species is limited by the NO adsorption in the presence of excess oxygen. Oxygen from either the gas phase or the bulk lattice reoxidizes the catalyst surface Vs4+-OH to V5+ = O layer by layer. Transport of oxygen in V2O5 from the bulk lattice to the surface occurs by a vacancy mechanism.
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Key words:
- transient response technique /
- catalyst /
- selective reduction /
- nitric oxides
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