氮氧化物和二噁英低温协同脱除催化剂研制和反应机理研究

The removal of nitrogen oxides (NOx) and Dioxin from waste incineration flue gas is becoming the major concern of air pollutant control with the strictness of environment standards. However, the existing mature technology of flue gas deNOx or Dioxin control is difficult to apply directly because of the low temperature of the general garbage incineration flue gas. In this project, dual-functional catalysts with balanced redox and acidic-basic properties will be designed and prepared, which will be further used to simultaneously catalytical removal of NOx and Dioxin at low temperatures. In this proposal, the pure and surface modified TiO2, zeolite and activated carbon are chosen as the supports, while the transition metals such as V、Cu、Mn、Ce、Mo and W are used as the active components to prepare supported or unsupported mixed-oxide catalysts. It is proposed to improve the low-temperature catalytic reactivity of removal NOx and Dioxin by increasing the catalytic oxidation capacity, and to decrease the side reactions such as NH3 and SO2 oxidation though regulating redox and acidic-basic properties. It is suggested to reveal the catalysis and SO2 poisoning mechanisms combining In-situ techniques、thermal analysis and high-resolution electronic microscopies. It is expected that the results of this project will be of much value to the understanding and reasonable design of catalysts for simultaneous removal of NOx and Dioxin emissions

随着我国环保标准的提高，垃圾焚烧烟气中的氮氧化物（NOx）和二噁英（Dioxin）成为重点控制的污染物，垃圾焚烧排烟温度较低，已有烟气脱硝和脱二噁英技术难已直接应用。本申请书拟设计制备氧化还原性和酸碱性相平衡的低温双功能催化体系，实现低温协同脱除NOx和二噁英，并探索NOx和二噁英协同脱除反应机理。本项目选取TiO2、分子筛和活性炭等材料为载体并进行一定的表面修饰，制备含有V、Cu、Mn、Ce、Mo、W等活性组分的负载型和非负载型复合金属氧化物催化剂，重点通过提升催化剂的低温氧化性提高低温脱硝协同脱二噁英的反应活性，同时平衡氧化还原性和酸碱性能以降低NH3、SO2氧化等副反应的发生；利用原位技术、热脱附技术以及高分辨电镜等揭示NOx和二噁英协同脱除机理，阐明SO2等特征污染物对催化剂的中毒机制，提高催化剂抗中毒能力，为实现垃圾焚烧烟气NOx和二噁英的高效协同脱除提供科学和技术支撑。

垃圾焚烧排烟温度低，烟气中NOx和二噁英等污染物难以采用现有技术实现高效脱除。针对该技术难题，我们一方面采用掺杂、界面电荷调控等策略设计制备活性高、选择性好以及抗中毒能力强的低温脱硝协同催化氧化二噁英催化剂体系，揭示催化剂结构与性能之间的构效关系；另一方面建立NOx和氯苯协同脱除动力学模型，阐明协同催化脱除NOx和氯苯的反应机理以及催化剂SO2中毒机制，为协同催化剂在实际工况下的应用提供技术支撑。具体地，我们分别选取过渡金属氧化物、活性炭和分子筛催化剂为研究对象，从催化原理与构效关系建立、催化剂设计与结构优化以及烟气适应性三个方面开展了系统性研究。在该项目的支持下我们首次确认了活性炭催化剂上脱硝活性位，厘清了苯环活化与开环的作用机理，明确了有机物氧化与SCR脱硝过程的相互作用机制；研究了V2O5/TiO2催化剂协同脱除NOx和氯苯的动力学过程，建立了V2O5/TiO2催化剂协同脱除NOx和氯苯的动力学模型；对于氧化物协同催化剂的设计与制备，针对V基催化剂，通过对TiO2进行Sn掺杂来调控载体物化性质，增强V基催化剂低温SCR活性和耐H2O和SO2性能；针对Ce基催化剂，通过SO2硫酸化处理，丰富其表面酸碱性后促进低温SCR活性的提升。最后，结合界面电荷转移调控和姜泰勒效应优化催化剂制备策略，改善催化剂的氧化还原性，解决协同控制中活性-选择性平衡难题，同时对催化剂结构进行调控（如核壳结构构筑、无机助剂表面修饰等）实现抗SO2、HCl、P、As等性能的提升，并对中毒机理进行深入研究。综上可知，该项目从协同催化剂的设计制备与结构优化入手，结合动力学模型建立和催化机理及其中毒机制研究，为垃圾焚烧烟气中NOx和二噁英等重点控制污染物的高效催化脱除和工业化应用提供技术支撑。