Effect of promoter species and precursors on catalytic activity of alkali metal promoted NiAl mixed oxides for N2O decomposition

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, FTIR, 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.