材料期刊网

采用溶胶?凝胶法合成纳米结构锌?铜混合铁氧体。XRD分析表明，不同组分Zn(1?x)CuxFe2O4(x=0.0,0.25,0.50,0.75)铁氧体为单相反尖晶石结构。随着铜含量的增加，晶粒尺寸增大。采用SEM表征样品的表面形貌，结果表明粒子为多孔结构。采用FT-IR和TEM分析所制备的样品。当x=0.75及催化剂为5%(摩尔分数)时，速率常数k值最高，这归因于高铜含量以及除Cu2+?Cu+和 Fe3+?Fe2+外，由于电荷相互作用而产生的混合位Cu2+?Fe+和/或Cu+?Fe2+离子对。混合氧化物活性增加归因于通过新离子产生而增大的活性位置浓度。随着锌含量的增加，颗粒尺寸增大。铁氧体粉末催化活性的变化是因为催化活性组分价态的变化，这能氧化从草酸镧中释放的一氧化碳。

Nanostructured zinc?copper mixed ferrite was synthesized using sol?gel method. Different compositions of ferrite, Zn(1?x)CuxFe2O4 (x=0.0, 0.25, 0.50, 0.75), characterized by XRD, reveal single phase inverse spinel in all the samples. With increasing copper content, the crystallite size increases. The surface morphology of all the samples, studied by SEM, shows porous structure of particles. The prepared samples were also analyzed by FT-IR and TEM. Catalytic activity of the samples was studied on lanthanum oxalate decomposition by thermogravimety .The rate constantk has the highest value withx=0.75 and 5% (mole fraction) of the catalyst and is attributed to high copper content, the mixed sites Cu2+?Fe+ and/or Cu+?Fe2+ ion pairs besides the one component sites Cu2+?Cu+, Fe3+?Fe2+, as a result of mutual charge interaction. In other words, the increasing activity of mixed oxides is attributed to increase in the content of active sites via creation of new ion pairs. With increasing Zn content, particle size increases. Variation of catalytic activity of ferrite powders is due to the changes of the valence state of catalytically active components of the ferrites, which oxidizes the carbon monoxide released from lanthanum oxalate.