Catalytic decomposition of N₂O over Ni_xCo_1-xCoAlO₄ spinel oxides prepared by sol-gel method

Ni_xCo_1-xCoAlO₄ spinel oxides with different compositions were prepared by sol-gel method and further modified with K₂CO₃ by incipient impregnation. The Ni_xCo_1-xCoAlO₄ spinel oxides were characterized by means of nitrogen physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature-programmed reduction by hydrogen (H₂-TPR); the effect of preparation parameters such as composition, mother liquid pH value, and potassium loading on their catalytic activity in N₂O decomposition was investigated. The results show that the K/Ni_0.15Co_0.85CoAlO₄ catalyst prepared with a pH value of 3 and a K/(Ni+Co) molar ratio of 0.1 is most active for N₂O decomposition; over it, N₂O can be completely decomposed into nitrogen and oxygen at 450 ℃ in the presence of oxygen. K-modified catalysts exhibit high catalytic activity, good reducibility and resistance towards water, as K species may be able to weaken the surface metal-oxygen bonds.