Mn/Ce-ZrO2催化剂低温NH3-SCR脱硝性能研究

采用浸渍法制备了三种具有不同载体的锰基NH₃低温选择性催化还原(NH₃-SCR)催化剂Mn/Ce-ZrO₂、Mn/P₂₅和Mn/Al₂O₃。研究了三种催化剂低温SCR脱硝活性及抗H₂O、抗SO₂性能,并采用XRD、NH₃-TPD和H₂-TPR手段对催化剂的物理化学性质进行表征。结果表明,在无H₂O和SO₂存在的情况下,三种催化剂的低温SCR催化活性均比较高。相对来说,Mn/Ce-ZrO₂在低温段(100~160℃)活性更高,Mn/P₂₅在高温段(160~220℃)活性更高,这与两种催化剂的氧化还原性质有关。H₂-TPR表征表明,Mn/Ce-ZrO₂更容易发生氧化还原反应,而Mn/P₂₅还原峰对应的温度较高、面积较大。三种催化剂均有很高的低温抗水性能。另外,Mn/Ce-ZrO₂的抗H₂O、抗SO₂性能最好,而Mn/P₂₅的抗H₂O、抗SO₂性能最差。Mn/Ce-ZrO₂具有较好的抗H₂O、抗SO₂性能是由于其具有较多的表面酸位点,且表面生成的硫铵盐不稳定。

Selective catalytic reduction of NO with NH3 over Mn-based catalysts at low temperature

Three Mn-based catalysts of Mn/Ce-ZrO₂, Mn/P₂₅, and Mn/Al₂O₃ with different supports were prepared by impregnation method and were used in the selective catalytic reduction of NO with NH₃ (NH₃-SCR) at low temperature. The catalysts were characterized by XRD, NH₃-TPD and H₂-TPR and their activity at low temperature as well as the resistances towards H₂O and SO₂ were investigated. The results showed that Mn/Ce-ZrO₂ exhibits better activity at low temperature (100~160℃) than other two catalysts, while Mn/P₂₅ performs better at high temperature (160~220℃), which is related with the redox characteristics of the catalysts. Mn/Ce-ZrO₂ is more easily to be reduced at low temperature while Mn/P₂₅ has a larger reduction peak at higher temperature, as revealed by H₂-TPR. All of the three catalysts have a good resistance to H₂O; among them Mn/Ce-ZrO₂ exhibits the best resistance to SO₂ and H₂O, which should be attributed to the abundant acid sites and the instability of ammonia sulfate formed on the surface of Mn/Ce-ZrO₂.