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Influence of thiourea modification on the NH3-SCR activity of CeO2: Simultaneous tuning morphology and surface acidity
Journal of the Energy Institute ( IF 5.6 ) Pub Date : 2021-07-14 , DOI: 10.1016/j.joei.2021.07.009
Wei Wang 1 , Zhibo Xiong 1, 2 , Weifeng He 1 , Wei Lu 1, 2 , Huancong Shi 3, 4
Affiliation  

Herein, thiourea (TA) was firstly used as the structure-directing agent to simultaneously tune the morphology and surface acidity of CeO2(w/o) synthesized via one-pot hydrothermal treatment, and exhibits better enhancement on its NH3-SCR activity than urea (UA). In addition, CeO2-TA(10) obtained at the suitable TA/Ce molar ratio of 10 presents the superior NH3-SCR activity in a broad temperature window. The introduction of thiourea promotes the formation of cubic CeO2 nanocubes in catalyst, but not the nanoparticles formed in CeO2(w/o) and CeO2-UA(10). Furthermore, the cubic CeO2 nanocubes mainly expose the crystal faces of {100}, which is helpful to the formation of more oxygen vacancies on the surface of CeO2-TA(10). At the same time, the formation of the specific sulfate species (CeOSO4) is also promoted under the influence of thiourea, thus simultaneously tunes the surface acidity of CeO2(w/o) by enhancing the Brønsted acid sites, although its Lewis acid sites are significantly decreased due to the diminution of the BET surface area. Compared with urea, the using of thiourea as the structure-directing agent also adjusts the physical-chemical properties of CeO2(w/o) and promotes its chemisorbed oxygen concentration. The results presented herein give a new thought for the development of state-of-the-art cerium-based catalysts for the NH3-SCR reaction.



中文翻译:

硫脲改性对CeO 2 NH 3 -SCR活性的影响:同时调整形态和表面酸度

在此,硫脲 (TA) 首次被用作结构导向剂,同时调整通过一锅水热处理合成的 CeO 2 (w/o)的形貌和表面酸度,并更好地增强其 NH 3 -SCR 活性比尿素(UA)。此外,在合适的 TA/Ce 摩尔比为 10 时获得的CeO 2 -TA(10)在宽温度范围内表现出优异的 NH 3 -SCR 活性。硫脲的引入促进了催化剂中立方CeO 2纳米立方体的形成,但不促进在CeO 2 (w/o)和CeO 2 -UA(10)中形成的纳米颗粒。此外,立方CeO 2纳米立方体主要暴露{100}的晶面,有助于在CeO 2 -TA(10)表面形成更多的氧空位。同时,在硫脲的影响下也促进了特定硫酸盐物质 (CeOSO 4 )的形成,从而同时通过增强布朗斯台德酸位来调节 CeO 2 (w/o)的表面酸度,尽管其路易斯酸由于 BET 表面积的减少,位点显着减少。与尿素相比,使用硫脲作为结构导向剂还调节了CeO 2的理化性质(w/o) 并提高其化学吸附氧浓度。本文提出的结果为开发用于 NH 3 -SCR 反应的最先进的铈基催化剂提供了新的思路。

更新日期:2021-07-21
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