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 Zn0.8Fe0.2Fe2O4-400 catalyst with the optimized composition and calcined at 400°C, the conversions of N2O in the absence and in the presence of steam achieve 63.5% and 22.2%, respectively, after reaction at 500°C for 10 h, which are much higher than those over Fe3O4. However, the K-doped Zn-Fe spinel oxides exhibited 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 FeOx surface that will inhibit the ferric species from reduction and active oxygen species from removal from the catalyst surface.