二氧化硫预处理对具有不同暴露晶面铈基催化剂NH3-SCR反应性能影响的研究

Nitrogen oxides (NOx) have caused a series of atmospheric pollution problems such as acid rain, photochemical smog and ozone depletion. Generally, NOx emissions are produced from stationary or mobile sources, including coal-fired power plants and vehicle engines. Selective catalytic reduction of NOx by NH3 (NH3-SCR) technique has been demonstrated as an effective NOx removal approach for stationary source. In practical working conditions, the effluent gases always contain a small amount of SO2. It was generally accepted that the catalytic performances of NH3-SCR catalysts were apparently affected by SO2 species. In this sense, interests were focused on the investigation of the interaction between the NH3-SCR catalysts and SO2. However, to the best of our knowledge, fewer was known for environmental friendly ceria-based NH3-SCR catalysts with respect to the shape/crystal plane effects of ceria with SO2 species for NH3-SCR. Herein, in this project, uniform CeO2 and MOx/CeO2(M=Ti, W, Mn, Cu) morphologies of different exposed crystallographic facets are selectively prepared and pretreated by SO2. These resultant catalysts are characterized by several analytical techniques, especially in-situ and ex-situ characterization techniques, to obtain a better understanding the NH3-SCR reaction mechanism of the ceria-based catalysts with the existence of SO2 species. With these efforts, we do really want to provide the basis of reference for the development and design of environmental friendly exhaust treatment catalysts with our own independent intellectual property rights.

抗硫性能是氨选择性催化还原（NH3-SCR）氮氧化物（NOx）催化剂研究中所关注的重点，同时也是难点，其关键在于如何了解和认识“SO2分子与催化剂不同表面结构相互作用的微观机制和规律，及其对催化性能的影响”这一基础问题。针对环境友好型铈基催化剂在SO2存在下的催化性能反而可以得到提升这一实验实事，本项目拟有意识地通过SO2气氛预处理具有不同暴露晶面的铈基模型催化剂，并且借助多种原位手段来探究SO2在铈基催化剂不同暴露晶面间上的吸附转化行为，以及SO2预处理前后反应物分子（NH3, NO, O2）在催化剂表面上的吸脱附性质和催化剂自身的变化，从而能够深入认识SO2存在时对铈基催化剂NH3-SCR催化作用机制的影响，这将为从分子层面设计和研发具有我国自主知识产权的环境友好型NH3-SCR催化剂提供理论指导。

抗硫性能是研制氨选择性催化还原（NH3-SCR）氮氧化物（NOx）催化剂所关注的重点，同时也是难点，其关键在于如何了解和认识“SO2分子与催化剂不同表面结构相互作用的微观机制和规律，及其对催化性能的影响”这一基础问题。针对环境友好型铈基催化剂在SO2存在下的催化性能反而可以得到提升这一实验实事，本项目（1）首先研究了不同暴露晶面二氧化铈的合成及其催化性能；（2）有意识地通过SO2气氛预处理具有不同暴露晶面的铈基模型催化剂，并且借助多种原位手段来探究SO2在铈基催化剂不同暴露晶面间上的吸附转化行为，以及SO2预处理前后反应物分子（NH3, NO, O2）在催化剂表面上的吸脱附性质和催化剂自身的变化；（3）进一步，我们研究了铈锆固溶体的制备及二氧化硫预处理对其NH3-SCR反应性能的影响规律；（4）发展了低温抗硫NH3-SCR催化体系；（5）为进一步提升催化剂的催化性能，我们开展了贵金属表面配位状态及其在环境催化中的反应性能研究；（6）将研究体系拓展到光催化体系。上述研究工作将为从分子层面设计和研发具有我国自主知识产权的环境友好型NH3-SCR催化剂提供理论指导。