Abstract A series of manganese oxide catalysts loaded on thermally modified Dolomite-palygorskite clay (MnOx/M-DPC) were synthesized by adopting impregnation, precipitation and citric acid methods and investigated for the selective catalytic reduction of NOx by NH3 (NH3-SCR) at low temperature. The results showed that the precipitated sample was more active (with 83% NOx conversion at 120 °C) by comparing it with the other MnOx/M-DPC samples prepared by impregnation and citric acid methods. Almost all NOx were completely removed by using this sample in the studied temperature range between 180 °C and 300 °C. In addition, all samples offered high N2 selectivity (> 94%) in the whole temperature range, and their SCR performance were affected by H2O introduction and NO oxidation to NO2 in the absence of NH3, but dependent on reaction temperature. The studied samples were characterized by specific surface area, pore size distribution, X-ray diffraction (XRD), Scanning electron microscope (SEM), electron diffraction spectra (EDS) and X-ray photoelectron spectroscopy (XPS). The results of specific surface area and pore size distribution suggested that the surface area and pore structure of catalysts obtained from various preparation methods were different, resulting in great difference in the catalytic performance. The irregular multi-modal mesoporous structure played a crucial role in the high catalytic activity over the precipitated MnOx/M-DPC sample. In addition, the results from XRD, SEM, EDS and XPS analyses indicated that Mn3O4 phase, good dispersion of manganese oxide, higher concentration of Mn as well as higher surface Mn4 + species, high lattice oxygen content on the surface were also beneficial to the superior catalytic efficiency of the precipitated sample.

中文翻译：

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通过各种方法制备的热处理白云石-坡缕石粘土负载的MnO x 催化剂用于NH 3 低温选择性催化还原（SCR）

摘要 采用浸渍法、沉淀法和柠檬酸法合成了一系列负载在热改性白云石-坡缕石粘土上的锰氧化物催化剂（MnOx/M-DPC），并研究了 NH3 选择性催化还原 NOx（NH3-SCR）在低温。结果表明，通过与其他通过浸渍和柠檬酸方法制备的 MnOx/M-DPC 样品进行比较，沉淀样品的活性更高（在 120°C 时具有 83% 的 NOx 转化率）。通过在 180 °C 和 300 °C 之间的研究温度范围内使用该样品，几乎所有的 NOx 都被完全去除。此外，所有样品在整个温度范围内都提供了高 N2 选择性（> 94%），并且它们的 SCR 性能受 H2O 引入和在没有 NH3 的情况下 NO 氧化为 NO2 的影响，但取决于反应温度。通过比表面积、孔径分布、X射线衍射（XRD）、扫描电子显微镜（SEM）、电子衍射谱（EDS）和X射线光电子能谱（XPS）对研究的样品进行表征。比表面积和孔径分布的结果表明，不同制备方法所得催化剂的表面积和孔结构不同，导致催化性能存在较大差异。不规则的多模态介孔结构对沉淀的 MnOx/M-DPC 样品的高催化活性起着至关重要的作用。此外，XRD、SEM、EDS 和 XPS 分析的结果表明，Mn3O4 相、锰氧化物的良好分散性、较高的 Mn 浓度以及较高的表面 Mn4+ 物种，