Background

Manganese oxides (MnO_x) are a promising catalyst in selective catalytic reduction of NO with NH₃ due to their excellent low-temperature catalytic activities. However, MnO_x still suffer from poor N₂ selectivity and SO₂ resistance.

Methods

In this work, rare earth element Pr was used to modify MnO_x catalysts via co-precipitation method, and the effects of Pr modification on SCR performance of MnO_x catalysts had been investigated.

Significant findings

The temperature window of MnPrO_x-0.1 catalyst with nearly 100% NO conversion efficiency ranged from 120 to 220 °C, and Pr modification on MnO_x catalyst had improved the resistance to SO₂ obviously. The characterization results indicated that Pr modification on MnO_x catalyst could increase the specific surface area, dispersity, reducibility, relative percentages of surface Mn⁴⁺ and chemisorbed oxygen species (O_α). NH₃-TPD and in-situ DRIFTS results revealed that Pr modification increased the adsorption of NH₃ on catalyst surface, resulting in more amount of Lewis acid sites on the surface of MnPrO_x-0.1 catalyst. All of these factors led to an excellent catalytic performance of Pr-modified MnO_x catalysts. In-situ DRIFTS results implied that SCR reactions over Pr-modified MnO_x catalyst followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms.

中文翻译：

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Pr 改性 MnOx 催化剂用于在低温下用 NH3 选择性还原 NO

背景

由于其优异的低温催化活性，锰氧化物 (MnO _x ) 是一种很有前途的催化剂，用于用 NH ₃选择性催化还原 NO 。然而，MnO _x仍然具有较差的N ₂选择性和耐SO ₂性。

方法

在这项工作中，稀土元素镨被用来修改的MnO _X通过共沉淀法催化剂，和Pr修饰对的MnO SCR性能的影响_X的催化剂进行了调查。

重要发现

NO转化率接近100%的MnPrO _x -0.1催化剂的温度窗口范围为120~220℃，MnO _x催化剂的Pr改性明显提高了对SO ₂的抗性。表征结果表明，MnO _x催化剂上的Pr改性可以增加比表面积、分散性、还原性、表面Mn ⁴⁺和化学吸附氧物种(O _α )的相对百分比。NH ₃ -TPD 和原位 DRIFTS 结果表明，Pr 改性增加了 NH ₃在催化剂表面的吸附，导致 MnPrO _x表面上更多的路易斯酸位点-0.1 催化剂。所有这些因素导致 Pr 改性的 MnO _x催化剂具有优异的催化性能。原位漂移结果表明 Pr 改性的 MnO _x催化剂上的 SCR 反应遵循 Eley-Rideal (ER) 和 Langmuir-Hinshelwood (LH) 机制。