In Situ UV Raman Study of the NOx Trapping and Sulfur Poisoning Behavior of Pt/Ba/γ-Al2O3 Catalysts
In Situ UV Raman Study of the NOx Trapping and Sulfur Poisoning Behavior of Pt/Ba/γ-Al2O3 Catalysts
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DOI：
10.1021/jp013191g
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发表时间：
2002
影响因子：
3.3
通讯作者：
D. Uy;Kelly A. Wiegand;A. O'neill;Andrea Dearth;W. Weber
中科院分区：
文献类型：
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作者：
D. Uy;Kelly A. Wiegand;A. O'neill;Andrea Dearth;W. Weber
在Pt/γ-Al_2 O_3和Pt/Ba/γ-Al_2 O_3催化剂上进行了244 nm激发的原位拉曼实验。Ba的添加允许普通催化剂在稀燃条件下以硝酸Ba的形式储存大量的NOx。使稀量的NO和/或SO2加上O2在N2中流过催化剂，选择温度和浓度以模拟在正常操作中遇到的NOx捕集和硫中毒特性。Pt/γ-Al_2O_3上的吸附物种主要为亚硝酸根/硝基和硫酸根，Pt上的主要为NO。在Pt/Ba/γ-Al 2 O3催化剂上，原位紫外拉曼光谱显示出典型的NOx捕集行为：NOx和SOx在贫燃条件下以Ba（NO3）2和BaSO 4的形式储存，在高温下以H2的形式释放。长时间的SO2暴露最终会使用于NOx储存的催化剂失活。通过在H2中加热至500 °C吹扫的硫酸盐不能完全从催化剂中除去，因为它可以在较低温度下重新出现而无需额外暴露于SO2。在Pt/γ-...
In situ Raman experiments excited with 244 nm radiation are carried out on Pt/γ-Al2O3 and Pt/Ba/γ-Al2O3 catalysts. The addition of Ba allows the normal catalyst to store substantial amounts of NOx as Ba nitrates under lean burn conditions. Dilute amounts of NO and/or SO2 plus O2 in N2 are flowed over the catalysts, with the temperatures and concentrations chosen to simulate the NOx trapping and sulfur poisoning characteristics encountered in normal operation. Adsorbed species observed on Pt/γ-Al2O3 are nitrite/nitro species and sulfate on γ-Al2O3 and NO on Pt. On Pt/Ba/γ-Al2O3, in situ UV Raman spectra showed typical NOx trap behavior: NOx and SOx are stored as Ba(NO3)2 and BaSO4 during lean conditions and released at higher temperatures in H2 flow. Prolonged SO2 exposure eventually deactivates the catalyst for NOx storage. The sulfate purged by heating to 500 °C in H2 is not completely removed from the catalyst, since it can reappear at lower temperature without additional exposure to SO2. On both Pt/γ-...