碱金属助剂类型及前驱物对改性NiAl复合氧化物催化分解N_2O活性的影响

Effect of promoter species and precursors on catalytic activity of alkali metal promoted NiAl mixed oxides for N_2O decomposition

制备了不同Ni/Al原子比的NiAl类水滑石样品,焙烧获得NiAl复合氧化物,用于N2O分解反应,研究了NiAl复合氧化物组成对催化活性的影响。在活性较高的NiAl复合氧化物表面浸渍碱金属碳酸盐溶液,制备改性NiAl复合氧化物,考察了碱金属类型(Na、K、Cs)和钾前驱物(K2CO3、K2C2O4、CH3COOK、KNO3)对改性催化剂活性的影响。用XRD、ICP-AES、FT-IR、BET、H2-TPR、XPS技术表征了催化剂的组成结构。结果表明,Ni/Al原子比为2.7的NiAl复合氧化物催化活性较高;Na、K、Cs碳酸盐改性NiAl复合氧化物均提高了催化剂活性,其中K的助剂效应最强。钾前驱物对K改性NiAl复合氧化物的催化活性有显著影响,其中碳酸钾、醋酸钾、草酸钾的加入明显提高了改性催化剂的催化活性,而加入硝酸钾反而降低了催化剂活性。

NiAl mixed oxides with Ni/Al atomic ratio of 2.0,2.7 and 4.1 were prepared by calcining the corresponding NiAl hydrotalcite-like compounds（NiAl-HLc）,and applied in N2O decomposition.The NiAl mixed oxide with Ni/Al atomic ratio of 2.7 was incipiently impregnated by alkali metal（Na,K,Cs） carbonate solution to prepare the promoted NiAl mixed oxide catalysts.The catalysts were characterized by XRD,ICP-AES,FT-IR,BET,H2-TPR and XPS techniques,and their catalytic activities for N2O decomposition were tested.The effect of NiAl mixed oxides composition,alkali metal species,and potassium precursors on catalytic activity was investigated.The results show that the catalytic activity of NiAl mixed oxide impregnated by K2CO3 solution is much higher than Na2CO3 and Cs2CO3 modified catalysts;the catalytic activity of NiAl mixed oxides is largely enhanced by the addition of K species from the precursors of K2CO3,K2C2O4 and CH3COOK.