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采用后合成法制备MnOx/Al-SBA-15催化剂,考察了催化剂的低温NH3选择性催化还原(SCR)NOx的性能.利用傅里叶变换红外(FTIR)光谱、N2吸附-脱附、X射线衍射(XRD)、扫描电镜(SEM)、拉曼(Raman)光谱、X射线光电子能谱(XPS)及NH3程序升温脱附(NH3-TPD)的表征手段,对催化剂的结构性质和SCR性能进行了系统分析.结果表明,适量Al的掺杂能提高MnOx/SBA-15催化剂的SCR活性,当硅铝摩尔比为50时,催化剂活性最佳.表征结果显示,Al掺杂后,催化剂仍保持良好的骨架结构,较大比表面积、孔容和孔径,并且Mn在催化剂表面富集,由低价态转化为高价态,MnO2为催化剂的主要活性相.此外,Al的掺杂使MnOx在催化剂表面高度分散,表面酸性增强,从而提高了催化剂的SCR活性.
The MnOx / Al-SBA-15 catalyst was prepared by post-synthesis method, and the performance of low temperature NH3 selective catalytic reduction (SCR) of NOx was investigated. The structure of the catalyst was characterized by Fourier transform infrared (FTIR) spectroscopy, N2 adsorption- XRD, SEM, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and NH3-TPD were used to characterize the structure and SCR performance of the catalyst The results show that the proper amount of Al doping can improve the SCR activity of MnOx / SBA-15 catalyst, and the catalyst activity is the best when the molar ratio of silicon to aluminum is 50. The characterization results show that the catalyst remains after Al doping Good framework structure, large specific surface area, pore volume and pore size, and Mn enrichment on the catalyst surface, from low valence state into high valence state, MnO2 as the main active phase of the catalyst.In addition, the doping of Al MnOx in the catalyst The surface is highly dispersed and the surface acidity is enhanced, thereby increasing the SCR activity of the catalyst.