新型低温抗硫M@MOF-Fe/TiO2（M=Mn、Cu、Ce）催化剂研制及SCR反应研究

Selective catalytic reduction (SCR) of NO with NH3 is a well-proven technology for the removal of NOx in exhaust gases from staionary. Howerever, there is still no low-temperature SCR catalysts available for practival applicaton to SO2-containing flue gases. Based on the NH3-SCR　reaction mechanism and sulfur poisoning resistant study of Fe-based catalysts, a new and sulfur durability catalyst of M@MOF-Fe/TiO2 (M=Mn、Cu、Ce) is designed and prepared in this study, in which M@MOF and Fe are chosen as the active components. Due to shape and size-selective properties of MOF, NO is adsorbed on MOF in presence of SO2, and then NO adsorbed is active by metal sites (M) with potential coordinative unsaturations of MOF. Therefore, at low temperature, there is occurrence of the SCR reaction between the active nitrate species formed on OMF and the adsorbed NH3 on the catalyst or ionic NH3 on Br?nsted acid sites introduced by sulfate species through L-H mechanism. Thus, the negative influence of SO2 on the catalytic activity can be eliminated, and sulfur tolerance of the catalyst can also be improved. Furthermore, the catalytic activity of M@MOF-Fe/TiO2 will be investigated and the NH3-SCR mechanism at low temperature is proposed. This study can help us fully comprehend the mechanisms of sulfur poisoning on SCR catalysts, and provide the theoretical and experimental basis for the design of SCR catalysts and the practical application.

针对当前低温NH3-SCR反应中催化剂抗硫中毒能力差的问题，本申请项目基于Fe基催化剂SCR反应机理和SO2中毒机理，设计和研制新型低温抗硫M@MOF-Fe/TiO2（M=Mn、Cu、Ce）复合催化剂。利用M@MOF孔道的可控性及其金属离子的催化活性，选择性吸附和活化NO，使其与催化剂本身吸附的NH3和利用SO2在催化剂表面吸附形成的新Br?nsted酸性位吸附的NH3，通过L-H机理进行反应生成N2和H2O。合理的将SO2的毒化作用转化为促进SCR反应的积极因素。考察反应运行参数对催化剂活性的影响，揭示低温SCR催化反应机理，识别影响抗硫性能的主要因素以及建立如何调控催化剂的方法，使催化剂可以在低温范围内具有高活性和高的抗硫性能。该项研究对于探索低温SCR反应及设计新型低温SCR催化剂具有重要的科学价值，并可为催化剂的实际应用提供理论支持。

本项目针对低温NH3-SCR反应中催化剂的低温活性差及抗硫中毒能力差的问题，拟通过制备新型MOF材料，利用MOF材料的比表面积大、孔道的可控性及其金属离子的催化活性的优点，将其与金属氧化物催化剂相结合，设计和制备在低温范围对NOx具有较高去除效果和高抗硫性能的SCR催化剂，并研究催化反应机理和抗硫机理等基础性科学问题。项目首先筛选和合成满足NH3-SCR反应要求的催化剂：MIL-100(Fe), Mn@MIL-100(Fe)和Mn@Ti-MIL-125，通过优化制备工艺和反应参数，制备的催化剂在低温范围对NOx具有较高的去除效率和较高的抗硫中毒能力；在此基础上，研究了新型MOF催化剂表面SCR反应机理以及金属活性中心在催化反应中的作用；为了理解和提高催化剂的抗硫性能，项目通过改变催化剂的活性中心含量、结构等参数，研究NH3-SCR反应中金属活性中心的相互作用、催化剂的结构等因素对催化剂抗硫性能影响，推导了影响催化剂抗硫中毒能力的主要因素，进而指导优化和调整催化剂。.课题研究成果可望为设计和制备新型的低温SCR催化剂提供新的研究思路，为实现低温NOx净化技术的应用和催化剂的开发提供一定的研究基础。