Hydrothermal deactivation of Fe-ZSM-5 catalysts for the selective catalytic reduction of NO with NH3
Hydrothermal deactivation of Fe-ZSM-5 catalysts for the selective catalytic reduction of NO with NH3
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DOI：
10.1016/j.apcatb.2010.11.006
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发表时间：
2011-01-14
影响因子：
22.1
通讯作者：
Althoff, Roderik
中科院分区：
文献类型：
--
作者：
Brandenberger, Sandro;Kroecher, Oliver;Althoff, Roderik
研究了在 10% H2O 存在下，Fe-ZSM-5 催化剂用于 NH3 还原 NO 的水热失活。通过 H-TPR、DRIFTS 对老化和新鲜催化剂进行了表征。 Al-27 NMR、Si-29 NMR、XAS 和氮物理吸附。对失活催化剂的分析表明，在适度老化的条件下，由于水解而脱铝仅发生在带有布朗斯台德酸性质子的Al位点上。此外，结果表明，水热老化的原因是Fe迁移，导致FeOx团簇的形成，FeOx团簇的尺寸随着催化剂年龄的增加而增大。这种 Fe 迁移与脱铝过程没有很强的相关性，并且 SCR 活性的稳定性更多地取决于离子交换位点中活性铁物质的稳定性，而不是框架本身的稳定性。这些活性铁位点的水热稳定性不受布朗斯台德酸质子的存在的显着影响。水热老化后的剩余活性是由位于离子交换位点的孤立铁离子引起的。基于这些结果，开发了水热条件下老化的一般机制，该机制区分铁氧化物的脱铝、迁移和聚集以及这些过程的时间顺序。 2010 Elsevier B.V. 保留所有权利。
The hydrothermal deactivation of Fe-ZSM-5 catalysts for the reduction of NO with NH3 in the presence of 10% H2O was studied. Aged and fresh catalysts were characterized by H-TPR, DRIFTS. Al-27 NMR, Si-29 NMR, XAS and nitrogen physisorption. The analysis of deactivated catalysts indicated that, under moderately aging conditions, dealumination due to hydrolysis occurs only on Al sites that bear a Bronsted acidic proton. Furthermore, the results showed that the cause of hydrothermal aging is Fe migration, which leads to the formation of FeOx clusters that increase in size as the age of the catalyst increases. This Fe migration was not strongly related to the process of dealumination and the stability with respect to SCR activity depends more on the stability of the active iron species in ion exchange sites than the stability of the framework itself. The hydrothermal stability of these active iron sites was not significantly influenced by the presence of Bronsted acid protons. The remaining activity after hydrothermal aging is caused by isolated iron ions located at ion exchange sites. Based on these results a general mechanism for aging under hydrothermal conditions was developed that differentiates between dealumination, migration and clustering of Fe oxides and the temporal sequence of these processes. 2010 Elsevier B.V. All rights reserved.