NH3-SCR Performance of Fresh and Hydrothermally Aged Fe-ZSM-5 in Standard and Fast Selective Catalytic Reduction Reactions
NH3-SCR Performance of Fresh and Hydrothermally Aged Fe-ZSM-5 in Standard and Fast Selective Catalytic Reduction Reactions
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新鲜和水热老化 Fe-ZSM-5 在标准和快速选择性催化还原反应中的 NH3-SCR 性能
DOI：
10.1021/es304421v
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发表时间：
2013-04-02
影响因子：
11.4
通讯作者：
He, Hong
中科院分区：
文献类型：
--
作者：
Shi, Xiaoyan;Liu, Fudong;He, Hong
水热稳定性是Fe - ZSM - 5催化剂在柴油发动机用氨选择性催化还原氮氧化物（NH₃ - SCR）实际应用中的挑战之一。由于快速SCR反应，废气中NO₂的存在可提高脱硝活性。在本研究中，采用固态离子交换法制备了Fe - ZSM - 5催化剂，并在800℃、10% H₂O存在的条件下进行水热失活处理。研究了新鲜的和水热老化的Fe - ZSM - 5催化剂在标准SCR（NO₂/NOₓ = 0）以及NO₂/NOₓ = 0.3和0.5的快速SCR中的活性。在标准SCR中，Fe - ZSM - 5的水热老化导致低温活性显著降低，高温活性略有提高。在快速SCR中，老化的Fe - ZSM - 5上的NOₓ转化率显著提高，但仍低于新鲜催化剂。此外，在快速SCR中，老化的Fe - ZSM - 5上N₂O的产生比新鲜催化剂明显得多。我们认为，在快速SCR中，与NO相关的关键反应速率在老化的Fe - ZSM - 5上比在新鲜催化剂上慢，从而增加了涉及N₂O形成的副反应的可能性。
Hydrothermal stability is one of the challenges for the practical application of Fe-ZSM-5 catalysts in the selective catalytic reduction (SCR) of NO with NH3 (NH3-SCR) for diesel engines. The presence of NO2 in the exhaust gases can enhance the deNOx activity because of the fast SCR reaction. In this work, a Fe-ZSM-5 catalyst was prepared by a solid-state ion-exchange method and was hydrothermally deactivated at 800 degrees C in the presence of 10% H2O. The activity of fresh and hydrothermal aged Fe-ZSM-5 catalysts was investigated in standard SCR (NO2/NOx = 0) and in fast SCR with NO2/NOx = 0.3 and 0.5. In standard SCR, hydrothermal aging of Fe-ZSM-5 resulted in a significant decrease of low-temperature activity and a slight increase in high-temperature activity. In fast SCR, NOx conversion over aged Fe-ZSM-5 was significantly increased but was still lower than that over fresh catalyst. Additionally, production of N2O in fast SCR was much more apparent over aged Fe-ZSM-5 than over fresh catalyst. We propose that, in fast SCR, the rate of key reactions related to NO is slower over aged Fe-ZSM-5 than over fresh catalyst, thus increasing the probabilities of side reactions involving the formation of N2O.