N2O在Mg-Fe复合氧化物上的催化分解

用共沉淀法制备了一组Mg-Fe复合氧化物催化剂,用于N₂O催化分解,考察了催化剂组成、焙烧温度、负载助剂钾等参数对其催化活性的影响。采用N₂物理吸附、X射线衍射、H₂-程序升温还原等技术对催化剂进行了结构表征。结果表明,500 ℃焙烧的Mg_0.6Fe_0.4Fe₂O₄催化剂对于N₂O分解反应有较高活性,而K改性的催化剂活性均有所降低,且K的负载量越高,改性催化剂的活性越低,这是由于负载的K粒子抑制了表面铁物种的还原,降低了催化剂的比表面积。在有氧无水、水氧共存条件下连续反应10 h,Mg_0.6Fe_0.4Fe₂O₄的催化活性和稳定性均显著高于FeO_x催化剂。

Catalytic decomposition of N2O over Mg-Fe mixed oxides

A series of Mg_xFe_1-xFe₂O₄ spinel oxides were prepared and characterized by means of nitrogen physisorption, X-ray diffraction (XRD) and temperature-programmed reduction of hydrogen (H₂-TPR). The effect of composition, calcination temperature, and potassium doping on the catalytic activity of the Mg-Fe mixed oxides in N₂O decomposition was investigated. The results indicated that the Mg_0.6Fe_0.4Fe₂O₄ catalyst calcined at 500 ℃ exhibits highest activity in N₂O decomposition. Unexpectedly, the catalyst activity is depressed by the addition of potassium, as the potassium doping may inhibit the reduction of surface iron oxides and reduce the surface area of K-modified catalysts. Long-term tests at 500 ℃ for 10 h also illustrate that Mg_0.6Fe_0.4Fe₂O₄ is superior to FeO_x catalyst either in the oxygen-alone or in the oxygen-steam concomitant atmosphere.