MnO2 Nanowire-CeO2 Nanoparticle Composite Catalysts for the Selective Catalytic Reduction of NO x with NH3.
MnO2 Nanowire-CeO2 Nanoparticle Composite Catalysts for the Selective Catalytic Reduction of NO x with NH3.
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DOI：
10.1021/acsami.8b09605
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发表时间：
2018-08
影响因子：
9.5
通讯作者：
Su Hyo Kim;B. C. Park;Yoo Sang Jeon;Y. K. Kim
中科院分区：
文献类型：
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作者：
Su Hyo Kim;B. C. Park;Yoo Sang Jeon;Y. K. Kim
mnox基催化剂由于具有较高的nox去除率和催化稳定性，已被应用于氨（NH3）选择性催化还原nox。一般来说，制造复杂结构的各种纳米材料需要复杂的工艺，包括热处理和一系列清洗步骤。此外，具有多种晶型的MnO2，根据其晶体结构表现出不同的催化效果。其中，作为纳米催化剂的ε-MnO2相的合成是最困难的，几乎没有报道。本文报道了用脉冲电流依次合成由ε-MnO2纳米线（NWs）和CeO2纳米粒子（NPs）组成的异质结构复合纳米催化剂。与传统技术相比，这种方法大大简化了整个过程。通过x射线衍射和透射电镜证实，ε-MnO2 NWs表面形成了2 ~ 3 nm的CeO2 NPs。从纳米催化剂的含量变化、比表面积和表面元素化学状态等方面分析了纳米催化剂的脱no效率。含有纳米催化剂的陶瓷过滤器在100-400°C的宽工作温度范围内显示出高的催化活性。在低温区，ε-MnO2对催化剂的催化性能起主要作用，这与brunauer - emmet - teller （BET）、H2程序升温还原（TPR）和x射线光电子能谱（XPS）结果一致。另一方面，在高温区域，效率随着CeO2含量的增加而逐渐提高。H2 - TPR、nh3 -程序升温解吸和XPS模式揭示了复合材料在上述温度范围内表现出如此优异特性的原因。
MnO x-based catalysts have been applied to the selective catalytic reduction of NO x with ammonia (NH3) owing to their high NO x removal efficiency and catalytic stability. In general, the fabrication of a variety of nanomaterials in a complex structure requires complicated processes, including heat treatment and a series of cleaning steps. In addition, MnO2 which has diverse polymorphs, exhibits different catalytic effects depending on its crystalline structure. Among them, synthesizing the ε-MnO2 phase, which functions as a nanocatalyst, has been the most difficult and has hardly been reported. Here, we report the synthesis of heterostructured composite nanocatalysts consisting of ε-MnO2 nanowires (NWs) and CeO2 nanoparticles (NPs) by applying pulsed currents sequentially. This method drastically simplifies the overall process compared to the conventional techniques. Through X-ray diffraction and transmission electron microscopy, it was confirmed that 2-3 nm of CeO2 NPs were formed on the surfaces of the ε-MnO2 NWs. The de-NO x efficiency of the nanocatalysts was analyzed in terms of content variation, specific surface area, and the elemental chemical state of the surface. A ceramic filter containing the nanocatalysts shows a high catalytic activity over the broad operating temperature range 100-400 °C. In the low-temperature region, ε-MnO2 plays a major role in determining the catalytic property, which is consistent with the Brunauer-Emmett-Teller (BET), H2 temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) results. On the other hand, in the high-temperature region, the efficiency increases gradually as the content of CeO2 increases. The H2 TPR, NH3-temperature-programmed desorption, and XPS patterns reveal why the composite exhibits such superior characteristics in the temperature range mentioned above.