碱金属改性的MnCu/γ-Al_2O_3催化剂催化分解N_2O性能

Performance of MnCu/γ-Al_2O_3 Catalysts Modified by Alkali Metal for N_2O Catalytic Decomposition

以γ-Al_2O_3为载体,采用浸渍法制备了MnCu复合金属氧化物负载量不同的MnCu/γ-Al_2O_3催化剂。考察了不同碱金属(Na、K、Rb)改性对MnCu/γ-Al_2O_3催化剂催化分解N_2O反应性能的影响。采用XRD、BET、H2-TPR、XPS和SEM等手段表征催化剂。结果表明,对于MnCu/γ-Al_2O_3催化剂,适宜的MnCu复合金属氧化物负载量为20%(Cat-20),此时添加碱金属K、Rb使Cat-20催化剂Mn—O键和Cu—O键弱化,降低了催化剂的还原温度,提高了Mn4+/Mn3+原子比,从而有利于提高Cat-20催化剂催化分解N_2O反应性能。当添加K、Rb的质量分数分别为6%时,Cat-20-K(6)和Cat-20-Rb(6)均具有相对较高的催化分解N_2O反应活性,其对应的N_2O完全转化的反应温度分别为510℃和500℃,而Na的添加对催化剂活性影响较小。

Using 7-AI2O3 as the support, a series of MnCu/γ-Al2O3 catalysts with different loading contents of Mn and Cu composite metal oxides were prepared by the impregnation method. The effect of different alkali metals （Na,K or Rb） doping in MnCu/γ-Al2O3 catalysts on N2O decomposition activity was investigated, and the catalysts were characterized by XRD, BET, H2-TPR, XPS and SEM. The results showed that the appropriate loading content of Mn and Cu composite metal oxides was 20% for MnCu/γ-Al2O3 catalyst. The bond energy of Mn-O and Cu -O was weakened as Cat-20 catalyst doped by alkali metals of K or Rb, which resulted in decreased reduction temperature and improved Mn^4 ＋/Mn^3＋ atomic ratio. Consequently, the Cat-20 catalyst was favorable to the NO decomposition reaction. Cat-20 -K （6 ） and Cat-20 -Rb （6 ） ,the catalyst doped 6 % content of alkali metal K and Rb, respectively, possessed a better N2O complete conversion temperature of 510℃and 500℃, respectively. However, alkali metal Na doped in catalyst displayed little effect on the catalytic activity.