Zn-Fe尖晶石型复合氧化物催化分解N2O

用共沉淀法制备了Zn-Fe尖晶石型复合氧化物催化剂,用于有氧气氛中N₂O的分解反应;考察了复合氧化物的组成、焙烧温度及K改性对其催化活性的影响,并用氮气吸附、XRD和H₂-TPR等技术对催化剂结构进行了表征。结果表明,Zn-Fe尖晶石型复合氧化物具有良好的催化N₂O分解的活性;在优化出的Zn_0.8Fe_0.2Fe₂O₄-400催化剂上500℃下连续反应10 h时,有氧无水和有氧有水条件下N₂O转化率分别达到63.5%和22.2%。K改性Zn-Fe尖晶石型复合氧化物的催化活性均不及纯Zn-Fe氧化物,这是由于K改性催化剂的比表面积显著降低,而且K粒子迁移至催化剂表面,抑制了FeO_x的还原和表面氧物种的脱除。

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.