有氧气氛中碱金属改性CuAl复合氧化物催化分解N2O的活性

合成了Cu/Al原子比分别为2.0、3.1、4.1的CuAl类水滑石样品,焙烧得到CuAl复合氧化物。在Cu/Al原子比为3.1的CuAl氧化物表面浸渍碱金属盐溶液,制备改性CuAl复合氧化物,用AES、XRD、FT-IR、BET、H₂-TPR、XPS等技术对催化剂进行了结构表征,考察了CuAl复合氧化物组成、碱金属助剂类型和K的前驱物对改性催化剂在有氧气氛中催化分解N₂O活性的影响。结果表明,Na、K、Cs改性CuAl复合氧化物均提高了催化剂活性,但K助剂的增强效应最显著;钾的不同前驱物改性CuAl复合氧化物的催化活性有显著差异,加入碳酸钾、草酸钾提高了催化剂的活性,而加入醋酸钾、硝酸钾反而降低了催化剂活性。优化出的K改性CuAl复合氧化物催化剂在含氧含水气氛的N₂O分解反应中表现出了较高的活性。

Catalytic activity of alkali metal doped Cu-Al mixed oxides for N2O decomposition in the presence of oxygen

Three CuAl hydrotalcite-like compounds(CuAl-HLc) with Cu/Al atomic ratio of 2.0,3.1 and 4.1 were prepared by a co-precipitation method and calcined to convert into CuAl mixed oxides.The CuAl mixed oxide with Cu/Al atomic ratio of 3.1 was incipiently impregnated by alkali metal(Na,K,Cs) salt solution to prepare the modified CuAl mixed oxide catalysts.The properties of the catalysts were characterized by AES,XRD,FT-IR,BET,H2-TPR and XPS techniques.The effect of CuAl mixed oxide compositions,alkali metal types and potassium precursors on catalytic activity for N2O decomposition in the presence of oxygen were investigated.It is revealed that the catalytic activity of CuAl mixed oxides impregnated by K2CO3 solution is higher than that of Na2CO3 and Cs2CO3 doped catalysts.In addition,the catalytic activity of CuAl mixed oxides can be largely enhanced by the addition of K species from the precursors of K2CO3 and K2C2O4,whereas KNO3-and CH3COOK-doped catalysts show a lower activity than sole CuAl oxide.The optimal K-doped catalyst exhibits a good activity for N2O decomposition in the presence of oxygen and steam.