Komaty Sarah, Andijani Marram, Wang Ning, Navarro de Miguel Juan Carlos, Kumar Veeranmaril Sudheesh, Hedhili Mohamed Nejib, Silva Cristina I Q, Wang Yan, Abou-Daher Mohamad, Han Yu, Ruiz-Martinez Javier
Physical Sciences and Engineering Division (PSE), KAUST Catalysis Center (KCC), Catalysis Nanomaterials and Spectroscopy (CNS), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia.
Physical Sciences and Engineering Division (PSE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Environ Sci Technol. 2024 Jul 31. doi: 10.1021/acs.est.4c01585.
Mn-based catalysts are promising candidates for eliminating harmful nitrogen oxides (NO) via selective catalytic reduction with ammonia (NH-SCR) due to their inherent strong redox abilities. However, poor water tolerance and low N selectivity are still the main limitations for practical applications. Herein, we succeeded in preparing an active catalyst for NH-SCR with improved water tolerance and N selectivity based on protecting MnO with a secondary growth of a hydrophobic silicalite-1. This protection suppressed catalyst deactivation by water adsorption. Interestingly, impregnating MnO on MesoTS-1 followed by silicalite-1 protection allowed for a higher dispersion of MnO species, thus increasing the concentration of acid sites. Consequently, the level of NO formation is decreased. These improvements resulted in a broader operating temperature of NO conversion and a modification of the NH-SCR mechanism. Diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that unprotected Mn/MesoTS-1 mainly followed the Eley-Rideal mechanism, while Mn/MesoTS-1@S1 followed both Langmuir-Hinshelwood and Eley-Rideal mechanisms.
锰基催化剂因其固有的强氧化还原能力，是通过氨选择性催化还原（NH-SCR）消除有害氮氧化物（NO）的有前途的候选材料。然而，耐水性差和N选择性低仍然是实际应用中的主要限制。在此，我们基于用疏水性硅沸石-1的二次生长保护MnO，成功制备了一种用于NH-SCR的活性催化剂，其具有改善的耐水性和N选择性。这种保护抑制了因水吸附导致的催化剂失活。有趣的是，在MesoTS-1上浸渍MnO后再进行硅沸石-1保护，可使MnO物种具有更高的分散度，从而增加酸位点的浓度。因此，NO生成水平降低。这些改进导致NO转化的操作温度范围更宽，并改变了NH-SCR机理。漫反射红外傅里叶变换光谱分析表明，未受保护的Mn/MesoTS-1主要遵循埃里-里德机理，而Mn/MesoTS-1@S1则同时遵循朗缪尔-欣谢尔伍德和埃里-里德机理。
