当前位置: X-MOL 学术Mol. Catal. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Revisit the effect of manganese oxidation state on activity in low-temperature NO-SCR
Molecular Catalysis ( IF 4.6 ) Pub Date : 2018-01-04 , DOI: 10.1016/j.mcat.2017.12.014
Jun Huang , He Huang , Licheng Liu , Hongtao Jiang

MnOx based catalysts exhibit excellent low-temperature activity in the selective catalytic reduction (SCR) of NOx by NH3. The effect of Mn oxidation state (chemical valence) on the NH3-SCR activity is an interesting topic and important for designing an active catalyst. This study aimed to clarify the intrinsic effect of Mn valence in NO-SCR reaction. For this purpose, the pure MnOx (MnO, Mn3O4, Mn2O3, MnO2) and physical mixed 30% MnOx/TiO2 catalysts, as well as three Mn/TiO2 catalysts prepared by impregnation, were investigated for the low temperature NO-SCR with NH3 in the presence of excess O2. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), X-ray Absorption Fine Structure (XAFS), and temperature programmed reduction of H2 (H2-TPR) to probe the physical and chemical properties of catalysts. The MnOx with different chemical valence exhibited distinct intrinsic activity. The Mn3O4 and MnO/TiO2 showed the highest intrinsic activity (TOR) for the unsupported and supported catalysts, respectively. The MnOx species with low chemical valence (MnO, Mn3O4) exhibited overall high intrinsic SCR activity (larger than 0.012 NO h−1 nm−2MnOx). The MnOx with different valence normally changed to higher oxidation state after physically mixed with TiO2. The content of MnOx species with different valence depended on their loading and Mn precursor, showing a totally different constitution. This work provides new insights into the Mn valence effect on the intrinsic activity for low-temperature SCR.



中文翻译:

再次探讨锰的氧化态对低温NO-SCR活性的影响

MnO x基催化剂在通过NH 3选择性催化还原NO x时表现出出色的低温活性。Mn氧化态(化学价)对NH 3 -SCR活性的影响是一个有趣的话题,对设计活性催化剂很重要。本研究旨在阐明锰价在NO-SCR反应中的内在作用。为此,使用纯MnO x(MnO,Mn 3 O 4,Mn 2 O 3,MnO 2)和物理混合的30%MnO x / TiO 2催化剂,以及三种Mn / TiO 2在过量O 2的存在下,研究了用NH 3进行低温浸渍法制备的浸渍催化剂。通过N 2吸附,X射线衍射(XRD),X射线吸收精细结构(XAFS)和H 2的程序升温还原(H 2 -TPR)来表征催化剂,以探查催化剂的物理和化学性质。化学价不同的MnO x表现出独特的内在活性。Mn 3 O 4和MnO / TiO 2分别对未负载型催化剂和负载型催化剂表现出最高的固有活性(TOR)。MnO x化学价低的物种(MnO,Mn 3 O 4)总体上具有较高的固有SCR活性(大于0.012 NO h -1  nm -2 MnOx)。在与TiO 2物理混合后,不同价态的MnO x通常会转变为较高的氧化态。不同价态的MnO x的含量取决于其负载量和Mn前驱体,显示出完全不同的组成。这项工作为锰价态对低温SCR固有活性的影响提供了新的见解。

更新日期:2018-01-04
down
wechat
bug