Catalytic decomposition of N2O over potassium-modified Cu-Co spinel oxides

Cu-Co spinel oxides with different compositions were prepared for N2O catalytic decomposition in the presence of oxygen. The active catalyst of Cu0.8Co0.2Co2O4 was incipiently impregnated by alkali metal salt solutions to prepare the modified catalysts. These catalysts were characterized by BET, XRD, SEM and XPS techniques, and their catalytic activity for N2O decomposition was tested. The effect of alkali metal species, potassium precursors and potassium loadings on catalytic activity was investigated. It was found that the catalytic activity of Cu0.8Co0.2Co2O4 modified by K2CO3 was much higher than that of bare oxide, while Cs/Cu0.8Co0.2Co2O4 was inferior to Cu0.8Co0.2Co2O4 for N2O decomposition. In the case of K/Cu0.8Co0.2Co2O4 with different potassium precursors, the catalyst activity was largely enhanced by the addition of K2CO3, while the doping of KNO3 and CH3COOK notably depressed the catalytic activity. Over the optimal catalyst of 0.05K/Cu0.8Co0.2Co2O4, 100% and 87.6% conversion of N2O was reached at 400°C under the atmosphere of oxygen only and oxygen-steam together, respectively. In addition, K2CO3-modified catalyst in both reaction atmospheres showed higher stability than un-modified catalyst.