Liu Jun, Lv Dengke, Liu Xiaoqing, Wang Ying, Zhao Yuqiong, Li Guoqiang, Si Wenzhe, Zhang Guojie
State Key Laboratory of Clean and Efficient Coal Utilization, College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China; College of Chemistry, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Clean and Efficient Coal Utilization, College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China.
J Colloid Interface Sci. 2025 Jan 15;678(Pt A):602-615. doi: 10.1016/j.jcis.2024.08.183. Epub 2024 Aug 25.
Selective catalytic oxidation of ammonia (NH-SCO) has become an effective method to reduce ammonia (NH) emissions, and is a key part to solve the problem of NH pollution. Nevertheless, the optimization of this technology's performance relies heavily on innovation and the development of catalyst design. In this study, a SmCuAgTiO catalyst with an asymmetric Ag-O-Ti-Sm-Cu ring active site was prepared and applied to the NH-SCO reaction. The low conversion of Cu-based catalysts in NH at low temperature and the inherent low N₂ selectivity of Ag-based catalysts were solved. The successful creation of the asymmetric ring active site improved the catalyst's reduction performance. Additionally, Cu, acting as an electron transfer medium, plays a crucial role in enhancing electron transfer within the asymmetric ring active site, thus increasing the redox cycle of the catalyst during the reaction. In addition, some lattice oxygen is lost in the catalyst, resulting in the formation of a large number of oxygen vacancies. This process stimulates the adsorption and activation of surface-adsorbed oxygen, facilitating the conversion of NH to an amide (NH) intermediate during the reaction and reducing non-selective oxidation. The N selectivity was improved without significantly affecting the performance of Ag-based catalyst. In-situ diffuse reflectance fourier transform infrared spectroscopy (In-situ DRIFTS) analysis reveals that the SmCuAgTiO catalyst primarily follows an "internal" selective catalytic reduction (iSCR) mechanism in the NH-SCO reaction, complemented by the imide mechanism. The asymmetric Ag-O-Ti-Sm-Cu ring active site developed in this study provides a new perspective for efficiently solving NH pollution in the future.
氨的选择性催化氧化（NH-SCO）已成为减少氨（NH₃）排放的有效方法，是解决氨污染问题的关键环节。然而，该技术性能的优化在很大程度上依赖于催化剂设计的创新与发展。本研究制备了具有不对称Ag-O-Ti-Sm-Cu环活性位点的SmCuAgTiO催化剂，并将其应用于NH-SCO反应。解决了铜基催化剂在低温下对NH₃转化率低以及银基催化剂固有的N₂选择性低的问题。不对称环活性位点的成功构建提高了催化剂的还原性能。此外，Cu作为电子传递介质，在增强不对称环活性位点内的电子传递方面起着关键作用，从而增加了反应过程中催化剂的氧化还原循环。此外，催化剂中一些晶格氧流失，导致形成大量氧空位。这一过程促进了表面吸附氧的吸附和活化，有利于反应过程中NH₃转化为酰胺（NH₂）中间体并减少非选择性氧化。在不显著影响银基催化剂性能的情况下提高了N₂选择性。原位漫反射傅里叶变换红外光谱（In-situ DRIFTS）分析表明，SmCuAgTiO催化剂在NH-SCO反应中主要遵循“内部”选择性催化还原（iSCR）机制，并辅以酰亚胺机制。本研究开发的不对称Ag-O-Ti-Sm-Cu环活性位点为未来有效解决氨污染提供了新的视角。
