Catalytic decomposition of N₂O over Zn-Fe spinel oxides

Zn-Fe spinel oxides were prepared by co-precipitation method and used as the catalysts in N₂O decomposition in the presence of oxygen; the effects of spinel oxide composition, calcination temperature, and K doping on their catalytic activity were investigated. In addition, the Zn-Fe spinel oxides were characterized by N₂ physisorption, X-ray diffraction and H₂-TPR techniques. The results indicated that the Zn-Fe spinel oxides are active in N₂O decomposition in the presence of oxygen; over the Zn_0.8Fe_0.2Fe₂O₄-400 catalyst with the optimized composition and calcined at 400℃, the conversions of N₂O in the absence and in the presence of steam achieve 63.5% and 22.2%, respectively, after reaction at 500℃ for 10h, which are much higher than those over Fe₃O₄. However, the K-doped Zn-Fe spinel oxides exhibit lower activity than the bare Zn-Fe oxide, as K doping may lead to a substantial decrease of surface area and the migration of potassium crystallites to FeO_x surface that will inhibit the ferric species from reduction and active oxygen species from removal from the catalyst surface.