State Key Laboratory for Oxo Synthesis and Selective Oxidation, and National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics , Chinese Academy of Sciences , Lanzhou 730000 , PR China.
ACS Appl Mater Interfaces. 2019 Oct 9;11(40):36598-36606. doi: 10.1021/acsami.9b08451. Epub 2019 Sep 26.
OMS-2 catalysts exhibit excellent selective catalytic reduction (SCR) activity at low temperature but weak HO resistance restricts its industrial application. To remarkably improve the water resistance of Mn-based catalysts is a key technical problem. In this work, the HO endurance and self-cleaning properties of OMS-2 catalysts are remarkably improved by the facile process, construction of hydrophobic coating. The performance of the hydrophobic layer on the bulk OMS-2 catalyst surface could be effectively controlled by adjusting the polydimethylsiloxane (PDMS) vapor deposition temperature. It is discovered that the 200 °C catalyst obtained super hydrophobic properties and formed with a contact angle of 160.3°, which not only exhibited satisfactory NH-SCR activity at low temperatures (140-300 °C) but also dramatically improved HO endurance and self-cleaning performance. Moreover, the mechanism of improving HO resistance and stability of the 200 °C catalyst was investigated in detail through a series of characterizations. Although the SCR activity of the 200 °C catalyst decreased slightly because of the combination of some active species (O and Mn) with PDMS, the HO passivation of the active species was eliminated. The advantage of self-cleaning was confirmed by the analysis of surface species and simulation experiments, which could avoid the accumulation of intermediates on the surface and promote the stability of the OMS-2 catalyst for NH-SCR at low temperature. This method of constructing special coating might be a huge step to remarkably improve the HO endurance properties of the catalyst and provided a new concept for future industrial application.
OMS-2 催化剂在低温下表现出优异的选择性催化还原（SCR）活性，但抗水能力弱限制了其工业应用。显著提高基于锰的催化剂的耐水能力是一个关键的技术问题。在这项工作中，通过简便的过程，构建疏水性涂层，显著提高了 OMS-2 催化剂的耐水性能和自清洁性能。通过调整聚二甲基硅氧烷（PDMS）蒸汽沉积温度，可以有效地控制疏水性层在块状 OMS-2 催化剂表面的性能。研究发现，在 200°C 下获得的催化剂具有超疏水性，接触角为 160.3°，不仅在低温（140-300°C）下表现出令人满意的 NH-SCR 活性，而且显著提高了耐水能力和自清洁性能。此外，通过一系列的表征详细研究了 200°C 催化剂提高耐水性和稳定性的机制。尽管由于一些活性物质（O 和 Mn）与 PDMS 的结合，200°C 催化剂的 SCR 活性略有下降，但活性物质的水钝化作用被消除了。通过对表面物种的分析和模拟实验证实了自清洁的优势，这可以避免表面中间体的积累，促进 OMS-2 催化剂在低温下 NH-SCR 的稳定性。这种构建特殊涂层的方法可能是显著提高催化剂耐水性能的一大步，并为未来的工业应用提供了一个新的概念。
