固体酸基脱硝催化剂的构筑及抗碱/碱土金属性能与机理研究

As one of the major air pollutants, nitrogen oxides (NOx) can promote the formation of haze. Therefore, the control of NOx is desirable. Selective catalytic reduction of NOx with NH3(NH3-SCR) is one of the most efficient technologies for the removal of NOx in the flue gas. However, deNOx catalyst is prone to be poisoned by the presence of H2O,SO2,alkali and alkaline earth metals in the flue gas, leading to the activity lost. In this project, solid acid based deNOx catalyst will be designed. The synergetic effect between the strong acidity of the solid acid and the redox property of the supported metal would lead to the improved catalytic performance and high resistance against the poisonous substances. Different catalyst characterization methods, in-situ diffuse reflectance infrared Fourier transform spectra(DRIFTS) and density functional theory(DFT) calculations will be used to reveal the active sites of the solid acid based catalyst and the relationship between the structure and the catalytic performance on the atomic and molecular levels. The reaction mechanism of NH3-SCR of NOx will be proposed. The results would shed light on designing novel deNOx catalyst with high activity and resistance against the poisonous substances. This project will promote the control of NOx with important academic and social significance.

氮氧化物（NOx)作为大气中的主要致霾污染物之一，其污染控制已刻不容缓。氨选择性催化还原NOx（NH3-SCR）是目前控制NOx的有效手段，但其存在的主要问题是燃煤烟气中的H2O、SO2、碱金属和碱土金属易导致脱硝催化剂中毒失活。针对这一问题，本项目拟构筑固体酸基脱硝催化剂，通过固体酸表面强酸性和负载金属氧化-还原性间的协同效应，提高催化剂在NH3-SCR反应中的活性和抗中毒性能。结合催化剂结构的分析表征、原位漫反射红外光谱（DRIFTS）和基于密度泛函理论（DFT）的分子模拟研究，从原子-分子水平上明确固体酸基脱硝催化剂的活性中心结构，揭示其结构与活性、抗中毒性能间的构效关系，阐明脱硝反应机理，从而为设计和发展高活性和抗中毒性能的脱硝催化体系提供科学指导。本课题的实施将推进解决我国致霾废气NOx的污染控制，具有重要的学术价值和社会意义。

NOx作为一种典型的致霾污染物，其污染控制对于改善空气质量具有重要意义。本项目对NH3选择性催化还原NOx（NH3-SCR）开展研究，并按照计划顺利完成。设计合成了W/Zr固体酸负载Cr催化剂、MoO3/MnZr催化剂、CeW双金属催化剂、FeNiTi以及硫酸化CeO2等催化剂，研究了其对NH3-SCR脱硝的性能，发现上述催化剂对NH3-SCR反应具有良好的催化活性和抗碱金属性能。借助N2吸附、XRD、XPS、H2-TPR、NH3-TPD等手段对催化剂的微观结构进行了分析表征，明确了催化剂的结构和性能的构效关系，发现催化剂表面的酸性及氧化-还原性的调控对催化剂的催化性能至关重要，双（或多）金属间的协同效应有助于提高催化剂的氧化-还原性及表面酸性，促进反应物的吸附与活化。借助原位漫反射红外光谱(DRIFTS)技术，揭示了NH3-SCR反应中产生的中间体的类别及其反应活性，明确了催化反应的路径，提出了NH3-SCR脱硝的反应机理。本项目的实施，对设计更高活性和抗碱金属性能的脱硝催化剂提供了重要的科学指导，对NOx的污染控制具有重要的科学价值和社会意义。