A Highly Effective Catalyst of Sm-MnOx for the NH3-SCR of NOx at Low Temperature: Promotional Role of Sm and Its Catalytic Performance

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• 作者：Dongmei Meng ; Wangcheng Zhan ; Yun Guo ; Yanglong Guo ; Li Wang ; Guanzhong Lu
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：October 2, 2015
• 年：2015
• 卷：5
• 期：10
• 页码：5973-5983
• 全文大小：844K
• ISSN：2155-5435

文摘

Sm-Mn mixed oxide catalysts prepared by the coprecipitation method were developed, and their catalytic activities were tested for the selective catalytic reduction (SCR) of NO with ammonia at low temperature. The results showed that the amount of Sm markedly influenced the activity of the MnO_x catalyst for SCR, that the activity of the Sm-Mn mixed oxide catalyst exhibited a volcano-type tendency with an increase in the Sm content, and that the appropriate mole ratio of Sm to Mn in the catalyst was 0.1. In addition, the presence of Sm in the MnO_x catalyst can obviously enhance both water and sulfur dioxide resistances. The effect of Sm on the physiochemical properties of the Sm-MnO_x catalyst were investigated by XRD, low-temperature N₂ adsorption, XPS, and FE-SEM techniques. The results showed that the presence of Sm in the Sm-MnO_x catalyst can restrain the crystallization of MnO_x and increase its surface area and the relative content of both Mn⁴⁺ and surface oxygen (O_S) on the surface of the Sm-MnO_x catalyst. NH₃-TPD, NO-TPD, and in situ DRIFT techniques were used to investigate the absorption of NH₃ and NO on the Sm-MnO_x catalyst and their surface reactions. The results revealed that the presence of Sm in the Sm_0.1-MnO_x catalyst can increase the absorption amount of NH₃ and NO on the catalyst and does not vary the SCR reaction mechanism over the MnO_x catalyst: that is, the coexistence of Eley鈥揜ideal and Langmuir鈥揌inshelwood mechanisms (bidentate nitrate is the active intermediate), in which the Eley鈥揜ideal mechanism is predominant.