Deactivation of Cu-SSZ-13 by SO2 exposure under SCR conditions
Deactivation of Cu-SSZ-13 by SO2 exposure under SCR conditions
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DOI：
10.1039/c5cy01288k
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发表时间：
2016-04
影响因子：
5
通讯作者：
Kurnia Wijayanti;Kirsten Leistner;S. Chand;Ashok Kumar;Krishna Kamasamudram;N. Currier;Aleksey Yezerets-Aleksey
中科院分区：
文献类型：
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作者：
Kurnia Wijayanti;Kirsten Leistner;S. Chand;Ashok Kumar;Krishna Kamasamudram;N. Currier;Aleksey Yezerets-Aleksey
Cu-SSZ-13 的失活研究是在 SCR 条件下使用 SO2 暴露进行的，并检查其对涉及 NH3-SCR 的不同反应的影响。在 300 °C SCR 条件下将催化剂暴露于 30 ppm SO2 90 分钟后，在 100–400 °C 的温度范围内研究了几种反应，包括 NH3 存储/TPD、NO/NH3 氧化、标准 SCR、快速 SCR 和含 75% NO2 的 SCR，以及 NH3–NO2 存储/TPD。使用 XRD、BET、ICP-SFMS 和 H2-TPR 对催化剂进行了表征。硫处理后 BET 表面积和孔体积下降，可能是由于硫和/或铵硫物质的堵塞。发现硫沿着整料通道并不均匀沉积。从 ICP-SFMS 测量可以明显看出，沉积从入口到出口发生。经过高达 400 °C 的 SCR 实验后，部分硫被去除。然而，这种去除仅在样品的入口一半中观察到，而在出口中没有观察到。氨 TPD 实验表明，硫中毒导致能够吸附氨的位置增加，从而导致氨储存量增加。此外，标准 SCR 在 SCR 条件下会因 SO2 中毒而显着失活。由于铵硫物质的位点阻挡效应，可用于氧化还原 SCR 循环的铜位点可能较少。此外，还观察了硫中毒对NH3氧化和NO2-SCR以及各种SCR反应中N2O产生的影响。最后发现，硫中毒的条件很关键，其中 SCR 条件（NH3 + NO + O2 + H2O）下的 SO2 失活比单独的 O2 + H2O 中的 SO2 中毒更严重。
A deactivation study of Cu-SSZ-13 has been conducted using SO2 exposure under SCR conditions and examining its effect on different reactions involving NH3-SCR. Several reactions, including NH3 storage/TPD, NO/NH3 oxidation, standard SCR, fast SCR and SCR with 75% NO2, as well as NH3–NO2 storage/TPD, were investigated at a temperature range of 100–400 °C after exposing the catalyst to 30 ppm SO2 under SCR conditions at 300 °C for 90 min. The catalyst was characterized using XRD, BET, ICP-SFMS and H2-TPR. The BET surface area and pore volume decreased after the sulfur treatment presumably due to blocking by sulfur and/or ammonium–sulfur species. It was found that sulfur was not uniformly deposited along the monolith channel. The deposition occurred from the inlet towards the outlet, as evident from ICP-SFMS measurements. Part of the sulfur was removed after an SCR experiment up to 400 °C. However, this removal was observed only in the inlet half of the sample and not in the outlet. Ammonia TPD experiments revealed that the sulfur poisoning resulted in additional sites that were capable of adsorbing ammonia, resulting in increased ammonia storage. Moreover, standard SCR was significantly deactivated by SO2 poisoning under SCR conditions. Due to the site-blocking effect of the ammonium–sulfur species, fewer copper sites are likely available for the redox SCR cycle. Furthermore, the effect of sulfur poisoning on NH3 oxidation and NO2-SCR as well as N2O production in various SCR reactions were observed. Finally, it was found that the conditions for the sulfur poisoning were critical in which SO2 deactivation under SCR conditions (NH3 + NO + O2 + H2O) was more severe compared to SO2 poisoning in O2 + H2O alone.