Zn-Fe尖晶石型复合氧化物催化分解N2O

摘要

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.s Fe0.2 Fe2 O4-400 catalyst with the optimized composition and calcined at 400 ℃,the conversions of N2 O 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 FeOx surface that will inhibit the ferric species from reduction and active oxygen species from removal from the catalyst surface.%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Zno.8Fe0.2Fe2O4-400催化剂上500℃下连续反应10h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FeOx的还原和表面氧物种的脱除.