School of Automotive and Traffic Engineering, Jiangsu University, Zhenjiang, 212013, China.
College of Automotive and Mechanical Engineering, Changsha University of Science and Technology, Yuhua District, Changsha City, 410114, Hunan, China.
Environ Sci Pollut Res Int. 2019 Sep;26(27):27888-27896. doi: 10.1007/s11356-019-05847-y. Epub 2019 Jul 25.
This study evaluated the NO adsorption and desorption performance as well as the casual relationship underlying a Mn-incorporated catalyst (Pt/Ba/Ce/xMn/γ-AlO). NO adsorption and desorption are regarded as a prominent index for the NO removal performance of NO storage and reduction; we utilized NO storage experiments with various inlet NO and O concentrations and cycling adsorption/desorption experiments with a couple of adsorption time protocols for performance evaluation. In-suit DRIFT and NO-TPD tests were implemented to reveal the instant stored species and their thermal stability. Eight percent of Mn catalyst at 350 °C was adopted in the described experiments for its desirable NO adsorption characteristics. The optimal NO storage performance was found under 10% O, deteriorating when the concentration was further increased. Furthermore, elevating NO concentration impaired the NO adsorption due to the low NO/NO ratio. It was also found that shorter adsorption time facilitated NO removal via maintaining an unsaturated state for active storage components in terms of a fixed desorption time. The stored species existed as nitrites and nitrates with a good low-temperature thermal stability which however decayed at higher temperatures as exhibited in the DRIFT and NO-TPD tests. These findings provided invaluable information for the application of Mn-incorporated catalyst for NO removal in diesel exhaust purification to relieve the aerial pollution.
本研究评估了负载 Mn 的催化剂 (Pt/Ba/Ce/xMn/γ-Al2O3) 的 NO 吸附和解吸性能及其内在的因果关系。NO 的吸附和解吸被认为是衡量 NO 存储还原法中 NO 去除性能的重要指标；我们利用具有不同入口 NO 和 O2 浓度的 NO 存储实验以及具有几种吸附时间方案的循环吸附/解吸实验来进行性能评估。采用原位 DRIFT 和 NO-TPD 测试来揭示即时存储物种及其热稳定性。在所述实验中，采用 350°C 时 8%的 Mn 催化剂，因其具有良好的 NO 吸附特性。在 10% O2 下，发现了最佳的 NO 存储性能，当浓度进一步增加时，性能会恶化。此外，由于低的 NO/NO2 比值，NO 浓度的升高会损害 NO 的吸附。还发现，较短的吸附时间通过在固定的解吸时间内保持活性存储成分的不饱和状态，有利于 NO 的去除。存储物种以亚硝酸盐和硝酸盐的形式存在，具有良好的低温热稳定性，但在 DRIFT 和 NO-TPD 测试中，在较高温度下会衰减。这些发现为在柴油机废气净化中应用负载 Mn 的催化剂去除 NO 以减轻空气污染提供了宝贵的信息。
