MnO x -ZSM-5脱硝催化剂制备的溶剂效应研究

MnO _x -ZSM-5脱硝催化剂具有较好的低温氨选择性催化还原反应（NH₃-SCR）活性，因其原料成本低、脱硝效率高等优点成为研究热点。详细叙述了采用蒸干溶剂法、通过调变制备过程中溶剂组成（乙醇和水或其混合溶液）制备系列MnO _x -ZSM-5催化剂，并首次研究了“溶剂效应”对催化剂脱硝性能产生影响的原因。利用X射线衍射（XRD）、光电子能谱仪（XPS）、程序升温氨吸附法（NH₃-TPD）、N₂物理吸附、氢气程序升温还原（H₂-TPR）以及扫描电子显微镜（SEM）等表征手段分析了催化剂物化性质、锰存在状态与催化性能之间的相互关系。结果发现，随着溶剂中水分占比的提高，MnO _x -ZSM-5脱硝催化剂的比表面积降低，具有高催化活性的Mn⁴⁺物种比例迅速下降，这些原因均导致催化剂的脱硝活性逐步降低。说明溶剂组成会影响催化剂的脱硝性能，因此在制备MnO _x -ZSM-5脱硝催化剂时选取合适的溶剂是至关重要的，这为如何制备高活性的MnO _x -ZSM-5脱硝催化剂提供了重要信息。

Study on solvent effect on preparation of MnO x -ZSM-5 deNO x catalysts

MnO _x -ZSM-5 deNO _x catalyst has good low?temperature NH₃-SCR activity.It has become a research hotspot because of the low raw material cost and high deNO _x efficiency.A series of MnO _x -ZSM-5 catalysts prepared by adjusting the composition of solvents（ethanol，water or their mixed solutions） with steam dry solvent method was described in detail.The reason of influence of“solvent effect” on the deNO _x performance of catalysts was studied for the first time.X-ray diffraction（XRD），X-ray photoelectron spectroscopy（XPS），temperature programmed ammonia adsorption（NH₃-TPD），N₂ physical adsorption，hydrogen temperature programmed reduction（H₂-TPR） and scanning electron microscopy（SEM） were used to analyze the relationship between the physical and chemical properties of the catalyst，the existing state of manganese and the catalytic performance.The results showed that the specific surface area of MnO _x -ZSM-5 deNO _x catalyst decreased，and the proportion of Mn⁴⁺ species with high catalytic activity decreased rapidly with increasing the proportion of water in the solvent，resulting in the gradual decrease of the deNO _x activity of the catalyst，which indicated that the solvent composition affected the deNO _x performance of the catalyst.Therefore，it was very important to select an appropriate solvent in the preparation of MnO _x -ZSM-5 deNO _x catalyst，which provided important information on how to prepare high activity MnO _x -ZSM-5 deNO _x catalyst.