铜掺杂对Fe/β催化剂NH_3-SCR催化性能的影响

制备了一系列Cu掺杂量不同的Fe/β(40)催化剂,并采用ICP-AES、XRD、H2-TPR、UV-vis和XPS等表征技术分析了催化剂的物化性质.结果表明,适量的铜掺杂能大大提高Fe/β(40)催化剂的低温活性,拓宽其活性温度窗口,但过量的Cu掺杂会降低催化剂的N2选择性.Cu掺杂质量比为1.27%Cu-2%Fe/β(40)的催化剂具有最佳的SCR性能,这与催化剂中存在较多离子交换位的Fe~(3+)和Cu~(2+)物种有关,而存在较多的CuO物种会促进氨高温氧化,使催化剂的N2选择性降低且高温窗口变窄.高温水热条件下Cu的存在可能使Cu、Fe物种更容易发生迁移和团聚,导致Cu-Fe/β(40)催化剂的水热稳定性明显变差.

The effect of Cu doping on catalytic performance of Fe/β catalyst for NH3-SCR

The Cu doped Fe/β (40) catalysts were prepared by ion-exchanged/wetness-impregnation methods and characterized using various analytical techniques, including H₂-TPR, XRD, UV-vis and XPS. Appropriate amount of copper enormously improved the low temperature activity of Fe/β (40) and broadened the temperature window of activity. Excessive amount of copper decreased the N₂ selectivity of catalysts. 1.27%Cu-2%Fe/β catalyst obtained the best performance attributed to many ion-exchanged positions of Fe³⁺ and Cu²⁺. However, a large amount of CuO can promote NH₃ oxidation at high temperature, and decrease N₂ selectivity and narrow down the temperature window of activity. Cu doping may make the migration and agglomeration of Cu and Fe species more easily under high-temperature hydrothermal conditions, which leads to hydrothermal stability of Cu-Fe/β (40) catalyst change.