The effect of SO2 on the sensitive layer of a NOx dosimeter
The effect of SO2 on the sensitive layer of a NOx dosimeter
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DOI：
10.1016/j.snb.2012.10.039
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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.;Hanft, D.;Moos, R.
累积型或积分型NOx传感器像剂量计一样工作，非常适合于低水平的NO和NO2的长期总量检测，同时从信号导数获得关于瞬时NOx浓度的信息。应用汽车催化剂中已知的钾基贫NOx捕集材料作为敏感材料。它以硝酸盐的形式积累氮氧化物，从而随着氮氧化物负载状态改变其电导率。由于SO2是已知的毒化的LNT的催化性能，SO2对传感特性的影响，现在解决。发现SO2和NO2之间对可访问存储位点的竞争以两种方式影响传感器信号：由于硫酸盐的形成，LNT材料的电阻在SO2的存在下降低，并且累积的NOx传感特性强烈降低。然而，通过在650 ℃下在含H-2气体中对敏感器件进行脱硫，获得了高的硫中毒可逆性。结果表明，与所提出的设置，SO2检测是可能的电导率和暴露的SO2量之间的线性相关性。由于在380 ℃时，对SO2的敏感性约为NOx的一半，因此需要关注交叉敏感性。在较高温度下，硝酸盐分解，传感器对SO2具有选择性。(C)2012年爱思唯尔B。V.保留所有权利。
The accumulating-type or integrating-type NOx sensor works like a dosimeter being well suited for long-term total amount detection of low levels of NO and NO2 while information about the instantaneous NOx concentration is obtained from the signal derivative. A potassium-based lean NOx trap material, known from automotive catalysts, is applied as sensitive material. It accumulates NOx in the form of nitrates and thereby changes its conductivity with the NOx loading state. Since SO2 is known to poison the catalytic properties of LNTs, the effect of SO2 on the sensing characteristics is addressed now. The competition between SO2 and NO2 for the accessible storage sites was found to affect the sensor signal in two ways: due to sulfate formation, the resistance of the LNT material decreases in the presence of SO2 and the accumulating NOx sensing properties are strongly reduced. However, a high reversibility of sulfur poisoning was obtained by desulfurization of the sensitive device at 650 degrees C in H-2 containing gas. The results reveal that with the presented setup, SO2 detection is possible with a linear correlation between the conductivity and the exposed SO2 amount. Since at 380 degrees C, the sensitivity to SO2 is about half compared to NOx, cross sensitivities need to be concerned. At higher temperatures nitrates are decomposed and the sensor is selective to SO2. (C) 2012 Elsevier B. V. All rights reserved.