核/壳结构低温SCR脱硝催化剂制备及其抗SO2中毒机理研究

Compared with the commercial V2O5-WO3(MoO3)/TiO2 catalyst, manganese-based catalysts show high low temperature NH3-SCR activity, but their active components can be easily sulfated at low temperature by SO2 in flue gas, thereby lose their NH3-SCR activity, which limits their industrial application in coal-burning power plant. TiO2/TiO2-ZrO2 are not be easy to be sulfated by SO2 at low temperature, and show poor adsorption of SO2 and low catalytic oxidized SO2 to SO3 activity, therefore, they are good inert additives for SO2 tolerance. In this research project, some active additives and inert additives are being doping in proper sequence to get the low-temperature nanometer core@shell structure manganese-based catalysts, which show high SO2 inhibition performance. Some characterization techniques will be employed to study the pore structure regulatory mechanism of inert additives shell by varying the preparation parameters such as the kinds of inert additives, and to investigate the effect of inert additives shell on the adsorption, diffusion and vulcanization of SO2 over the surface of nanometer manganese-based catalysts, and finally reveal the optimization mechanism of inert additives shell on their anti-SO2 poisoning. The effect of operation parameters on the NH3-SCR activity of the low-temperature namometer core@shell structure manganse-based catalysts will be investigated in detail by means of the denitrogen test, and then their reaction kinetics model for selective catalytic reduction of NO will be set up. The adsorption/desorption capacity of NO and NH3 over low-temperature namometer core@shell structure manganse-based catalysts is also investigated to study its surface acid through temperature programed desorption methods(TPD), and the intermediate material of NO/NH3+NO adsorption over catalysts will be characterized by diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) in order to reveal the NH3-SCR mechanism of the low-temperature namometer core@shell structure manganse-based catalysts. This research will lay the theoretical foundation for the low-temperature NH3-SCR technology being used to reduce NOx emission from coal-burning power plant.

与商业钒钨钛催化剂相比，锰基催化剂具有良好低温SCR脱硝活性，但低温时其活性组分易被烟气中SO2硫化而失活，限制了其在燃煤电站的工业应用；TiO2/TiO2-ZrO2等低温时不易被SO2硫化，为抗SO2毒化性能强的惰性助剂。本项目通过依次掺杂活性助剂、惰性助剂，得到抗SO2毒化性能强的核壳结构低温纳米锰基催化剂；借助催化剂表征手段，研究惰性助剂种类等对惰性助剂壳层微观孔隙结构的调控机制，探讨惰性助剂壳层对SO2在锰基催化剂表面吸附、扩散及硫化的作用规律，揭示惰性助剂壳层提高锰基催化剂抗SO2中毒性能机理；利用脱硝实验台考察核壳低温纳米锰基催化剂SCR脱硝特性，建立其催化脱硝反应力学模型；利用TPD研究其表面NO/NH3脱吸附特性，借助DRIFTS表征NO/NO+NH3等在核壳低温纳米锰基催化剂表面的吸附中间产物，确定其SCR脱硝机理。此研究将为燃煤电站采用低温SCR脱硝技术奠定理论基础。

商业钒钨钛系列催化剂存在脱硝温度窗口高、钒有毒等问题，开发抗SO2中毒性能良好的低温锰基催化剂及其它替代催化剂具有重要意义。本项目研究了铁、铈等助剂掺杂对锰氧化物低温SCR脱硝性能及抗SO2中毒性能的促进作用；表征分析了助剂掺杂对锰基催化剂物性结构的作用规律，揭示了锰基催化剂SO2中毒机制，确定了其NH3-SCR脱硝机理，并探讨了钛等包裹对锰基催化剂低温脱硝及抗SO2中毒性能的影响。针对低温锰基催化剂活性组分锰易硫化这一关键问题，开展了铁基内核/钛基外壳等催化剂的优化及脱硝机理研究；利用共沉淀-微波法构筑了新型铁基/磁性铁基复合氧化物SCR脱硝催化剂，表征了助剂掺杂等对铁氧化物/磁性铁氧化物晶相、孔隙结构、表面元素浓度分布及酸位的作用规律，揭示了助剂掺杂等对铁基/磁性铁基催化剂SCR脱硝的促进机制。基于铁、铈、钨、钛组分良好的抗SO2中毒性能、H2O2氧化性及其与Ti4+络合性能，利用微波辅助柠檬酸溶胶-凝胶法构筑了新型磁性铁铈钨复合氧化物SCR脱硝催化剂，确定了该新型催化剂的制备参数；并首次将H2O2用于络合修饰铈钨钛复合氧化物的制备，确定了H2O2络合修饰对铈钨钛复合氧化物催化剂物性和脱硝性能的作用规律。最后，利用分步沉淀构筑了Ce@Ce-W-Ti复合氧化物催化剂，表征分析了铈源对该催化剂物性结构的影响规律。此项目研究结果丰富了催化脱硝理论，可为新型SCR脱硝替代催化剂的研制提供理论指导。