The electrical properties of NOx-storing carbonates during NOx exposure
The electrical properties of NOx-storing carbonates during NOx exposure
复制标题
DOI：
10.1016/j.ssi.2012.05.009
复制
发表时间：
2012-10-04
影响因子：
3.2
通讯作者：
Moos, R.
中科院分区：
文献类型：
--
作者：
Gross, A.;Bishop, S. R.;Moos, R.
为了更深入地了解多组分汽车催化剂系统和集成型NOx传感器中的不同组分，研究了原位电学方法。研究了汽车NOx存储催化剂中关键组分BaCO3和K2CO3的电导率随气体组成和温度的变化。BaCO3，K2CO3，和两者的等摩尔混合物上进行的阻抗测量表明，在所有情况下，在NO2气体的存在下，随着碳酸盐表面上的渐进NOx吸附的电阻降低。将吸湿但低电阻率的K2CO3与非常高电阻但稳定的BaCO3混合导致比单独的K2CO3更大的稳定性，以及测量电阻率变化的改进的能力。从气流中除去NO2后，混合物的电阻恢复到其值的约50%，据信这是由于吸附的NOx从K迁移到Ba，而不是单独解吸。NOx捕集器材料的这些结果表明，原位阻抗谱测量提供了贫NOx捕集器催化剂组分中NOx负载水平的实时表征。(C)2012爱思唯尔有限公司版权所有。
In order to gain a deeper understanding of the different components in multi-component automotive catalyst systems and integrating type NOx-sensors, in-situ electrical methods are examined. The conductivity of BaCO3 and K2CO3, key components in automotive NOx storage catalysts, was examined as a function of gas composition and temperature. Impedance measurements performed on BaCO3, K2CO3, and equimolar mixtures of both, demonstrated that, in all cases, the resistance decreases in the presence of NO2 gas with progressive NOx sorption on the carbonate surface. Mixing the hygroscopic but low resistivity K2CO3 with the very highly resistive but stable BaCO3 resulted in greater stability than K2CO3 alone, as well as improved ability to measure resistivity changes. The resistance of the mixture recovered about 50% of its value after removing NO2 from the gas stream, believed to result from migration of sorbed NOx from K to Ba, instead of desorption alone. These results on NOx trap materials show that in-situ impedance spectroscopy measurements offer real-time characterization of NOx loading levels in lean NOx trap catalyst components. (C) 2012 Elsevier B.V. All rights reserved.