CuCl/γ-Al_2O_3上NO脱除过程研究

Reaction Mechanism of NO Conversion over CuCl/γ-Al_2O_3

设计了一系列的对比实验 ,利用 XRD、XPS、TPR、EXAFS等技术 ,系统研究了 Cu Cl/γ- Al2 O3上的 NO脱除反应过程 .结果发现 ,Cu Cl/γ- Al2 O3样品暴露在空气中 ,表面被部分氧化生成 Cu Cl2 及 Cu O等 .在高温处理和反应过程中 ,造成样品表面氯的损失 ,同时生成更多的 Cu O.因而重新还原处理后测活性时 ,得到高分散的金属铜 ,使样品的 NO分解活性提高 .但由于 NO对低价铜有很强的氧化作用 ,NO可通过氧化还原反应转化为 N2 ,同时将 Cu0 及 Cu+ 氧化为无活性的 Cu2 + ,从而引起 NO转化活性下降 .

A series of comparision tests were designed to examine the reaction mechanism of NO conversion over CuCl/ γ Al 2O 3 by using XRD, XPS, TPR and EXAFS techniques. The results show that, when CuCl/ γ Al 2O 3 is exposed to air, CuCl is partially oxidized to CuCl 2 and CuO etc. In the course of heat treatment and reaction at high temperature, Cl content in the sample decreases and CuO content increases. As a result, highly dispersed metal Cu is obtained when the sample is reduced again , and higher NO conversion is obtained. This is the reason for the enhancement of NO conversion over used sample. However, NO has a strong oxidizing effect to low valence copper, it can be converted to N 2 through redox reaction, and at the same time, Cu 0 and Cu + are oxidized to Cu 2+ which has no activity for NO conversion. This is the reason of deactivation of the catalyst.