高效铈基脱硝催化剂的创制及其催化性能和抗硫机理研究

Nitrogen oxides (NOx) are one of the main precursors of PM2.5 and O3. Therefore, the thorough purification treatment of NOx is very crucial and urgent to control the increasingly serious composite air pollution in China. The selective catalytic reduction of NOx by NH3 (NH3-SCR) has been proved to be one of the most effective approaches for the elimination of NOx from stationary sources (e.g., coal-fired power plants) and mobile sources (e.g., diesel vehicles). How to create environment-friendly deNOx catalysts with high thermal stability, excellent catalytic performance, and strong sulfur-resistance ability is the bottleneck to restrict the development of NH3-SCR technique. Considering the abundant resources and excellent catalytic performance of rare earth element for NOx elimination, we plan to synthesize supported ceria-based catalysts with high thermal stability, large BET specific surface area, mesoporous structure, and specific exposed crystal plane to further enhance the catalytic performance and sulfur-resistance performance in NH3-SCR reaction. Moreover, the influence of mesoporous structure and specific exposed crystal plane of the support on the coordination structure, dispersion state, redox property, and surface acidity of the active species will be investigated deeply with the aid of a series of characterization means. Finally, we attempt to use some in situ and quasi situ characterization techniques to explore the NH3-SCR reaction mechanism and sulfur-resistance mechanism at molecular and atomic level. Through the implementation of this project, it is expected to provide some scientific basis for the fabrication of novel, efficient, and practical deNOx catalysts.

氮氧化物(NOx)是PM2.5和O3的主要前驱物之一，对其进行深入的净化治理对于控制我国日益严峻的大气复合污染非常关键而紧迫。实践证明，NH3-SCR技术是消除固定源(如燃煤电厂)和移动源(如柴油车)NOx的最有效手段之一。如何创制出环境友好的热稳定性高、催化性能优和抗硫能力强的脱硝催化剂一直是制约该技术发展的瓶颈问题。针对我国丰富的稀土资源及其优异的NOx催化消除性能，本项目拟通过合成高热稳定性且高比表面积的具有介孔结构和特定暴露晶面的负载型铈基催化剂来进一步提高其在NH3-SCR中的催化性能和抗硫性能，并借助于多种表征手段深入考察载体的介孔结构和暴露晶面对活性组分的配位结构、分散状态、氧化还原性能和表面酸性等的影响规律，进而运用多种原位和准原位表征技术从分子原子层面探讨催化剂表面的NH3-SCR反应机理和抗硫机理。通过本项目的实施，有望为开发新型、高效和实用的脱硝催化剂提供科学依据。

氮氧化物(NOx)是PM2.5和O3的主要前驱物之一，对其进行深入的净化治理对于控制我国日益严峻的大气复合污染非常关键而紧迫。实践证明，氨-选择性催化还原(NH3-SCR)技术是消除固定源(如燃煤电厂)和移动源(如柴油车) NOx的最有效手段之一。如何创制出环境友好的热稳定性高、催化性能优和抗硫能力强的脱硝催化剂一直是制约该技术发展的瓶颈问题。针对我国丰富的稀土资源及其优异的NOx催化消除性能，本项目以稀土CeO2为主要研究对象。通过本项目的实施，我们发展了高热稳定性且高比表面积的具有介孔结构和特定暴露晶面的CeO2纳米立方体、CeO2纳米多面体、CeO2纳米棒、CeO2-ZrO2纳米棒、CeO2-Al2O3纳米棒和CeO2-SiO2纳米棒的合成方法，并优化出了最佳的制备条件。同时，将TiO2、MnOx负载到这些载体表面，并通过表面改性和溶剂调变等策略制备出了一系列脱硝性能和抗水抗硫性能优异的负载型铈基催化剂。在此基础上，我们运用TEM、XRD、Raman、XPS、H2-TPR和NH3-TPD等多种表征手段深入考察了铈基载体的结构和暴露晶面对催化剂的氧化还原性能和表面酸性等理化性质的影响规律，并构建了催化剂“组成-结构-性能”之间的构效关系；进一步借助于原位漫反射红外光谱等原位表征技术从分子原子层面阐明了催化剂表面的NH3-SCR反应机理和抗硫机制。本项目的实施为开发新型、高效和实用的脱硝催化剂提供了重要的科学依据，为我国环保事业的发展贡献了一份力量。