State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029, PR China.
State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029, PR China.
J Environ Sci (China). 2021 May;103:219-228. doi: 10.1016/j.jes.2020.10.008. Epub 2020 Nov 17.
Manganese oxides supported by ZSM-5 zeolite (Mn/ZSM-5) as well as their further modified by Ce promoter were achieved by simple impregnation method for ozone catalytic decomposition. The yCe20Mn/ZSM-5-81 catalyst with 8% Ce loading showed the highest catalytic activity at relative humidity of 50% and a space velocity of 360 L/(g × hr), giving 93% conversion of 600 ppm O after 5 hr. Moreover, this sample still maintained highly activity and stability in humid air with 50%-70% relative humidity. Series of physicochemical characterization including X-ray diffraction, temperature-programmed technology (NH-TPD and H-TPR), X-ray photoelectron spectroscopy and oxygen isotopic exchange were introduced to disclose the structure-performance relationship. The results indicated that moderate Si/Al ratio (81) of zeolite support was beneficial for ozone decomposition owing to the synergies of acidity and hydrophobicity. Furthermore, compared with 20Mn/ZSM-5-81, Ce doping could enhance the amount of low valance manganese (such as Mn and Mn). Besides, the Ce/Ce ratio of 8Ce20Mn/ZSM-5-81 sample was higher than that of 4Ce20Mn/ZSM-5-81. Additionally, the synergy between the MnO and CeO could easily transfer electron via the redox cycle, thus resulting in an increased reducibility at low temperatures and high concentration of surface oxygen. This study provides important insights to the utilization of porous zeolite with high surface area to disperse active component of manganese for ozone decomposition.
采用简单浸渍法制备了负载在 ZSM-5 沸石上的氧化锰（Mn/ZSM-5）及其进一步用 Ce 助剂改性的催化剂，用于臭氧催化分解。在相对湿度为 50%和空速为 360 L/（g×hr）的条件下，负载量为 8%Ce 的 yCe20Mn/ZSM-5-81 催化剂具有最高的催化活性，在 5 小时后，600 ppm O 的转化率达到 93%。此外，该样品在相对湿度为 50%-70%的潮湿空气中仍保持着很高的活性和稳定性。采用 X 射线衍射、程序升温技术（NH-TPD 和 H-TPR）、X 射线光电子能谱和氧同位素交换等一系列物理化学表征方法，揭示了结构-性能关系。结果表明，沸石载体具有适中的 Si/Al 比（81）有利于臭氧分解，这是由于酸性和疏水性的协同作用。此外，与 20Mn/ZSM-5-81 相比，Ce 掺杂可以增加低价锰（如 Mn 和 Mn）的含量。此外，8Ce20Mn/ZSM-5-81 样品的 Ce/Ce 比值高于 4Ce20Mn/ZSM-5-81。此外，MnO 和 CeO 之间的协同作用可以通过氧化还原循环容易地转移电子，从而导致在低温下增加还原度和表面氧的高浓度。本研究为利用具有高比表面积的多孔沸石来分散氧化锰的活性组分用于臭氧分解提供了重要的见解。
