Electrical conductivity study of NOx trap materials BaCO3 and K2CO3/La-Al2O3 during NOx exposure
Electrical conductivity study of NOx trap materials BaCO3 and K2CO3/La-Al2O3 during NOx exposure
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DOI：
10.1016/j.snb.2013.01.083
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发表时间：
2013-10-01
影响因子：
8.4
通讯作者：
Moos, R.
中科院分区：
文献类型：
--
作者：
Gross, A.;Weller, T.;Moos, R.
碱性（土）碳酸盐应用于氮氧化物储存和还原催化剂，因为它们能够在过量氧气环境中积累NO2，并在富燃条件下释放它。它们的电导率对NOx负载状态的依赖性使得它们适合作为NO2敏感层，并且能够原位表征这种催化剂体系的状态。通过阻抗谱分析了具有不同形貌的NOx捕集组分BaCO 3和K2 CO 3在各种含NOx气氛中的电导率。虽然逐步吸收的NO2可以检测到电对两种碳酸盐，只有一个弱的相应的影响NO检测。碳酸盐的电导率在NO2积累过程中的增加可以被描述为一个扩散控制的过程，在BaCO 3的情况下具有特征的成核延迟。比较在250至600摄氏度的未加载和NO2饱和状态下的碳酸盐的电导率的Arrhenius样图显示，BaCO 3的电导率比K2 CO 3/La-Al 2 O3的电导率对NO2更敏感，但后者表现出约5个数量级的电导率。(C)2013年爱思唯尔B。V.保留所有权利。
Alkaline (earth-) carbonates are applied in NOx storage and reduction catalysts, given their ability to accumulate NO2 in excess oxygen environments, and releasing it under rich-burn conditions. The dependency of their conductivity on the NOx loading state makes them suitable as NO2 sensitive layers and enables the in situ characterization of the status of such catalyst systems. The conductivity of the NOx trap components BaCO3 and K2CO3, with different morphologies, is analyzed in various NOx containing atmospheres by impedance spectroscopy. While the stepwise uptake of NO2 can be detected electrically on both carbonates, only a weak corresponding influence of NO is detected. The increase in the conductivity of the carbonates during NO2 accumulation can be described as a diffusion controlled process with a characteristic nucleation delay in the case of BaCO3. Arrhenius-like plots comparing the conductivities of the carbonates in the unloaded and NO2 saturated states from 250 to 600 degrees C reveal that the conductivity of BaCO3 is more sensitive to NO2 than those of K2CO3/La-Al2O3, but the latter exhibiting about five orders of magnitude higher conductivity. (C) 2013 Elsevier B. V. All rights reserved.