铁/多孔玻璃催化剂的原位穆斯堡尔谱研究

INVESTLGATION ON THE REDUCTION PROCESS OF POROUS GLASS SUPPORTED IRON OXIDES BY TPR IN SITU MSSBAUER SPECTROSCOPY

采用高比表面积的多孔玻璃为载体，制备了一系列不同氧化铁负载量的催化剂，运用程序升温还原－ 原位穆斯堡尔谱（ Ｔ Ｐ Ｒ Ｉｎ ｓｉｔｕ Ｍｏｓｓｂａｕｅｒ） 谱联用技术研究了催化剂的还原过程．实验发现样品的 Ｔ Ｐ Ｒ 谱有三个还原峰，表明氧化铁在多孔玻璃载体上的还原经历了三个阶段，氧化铁与多孔玻璃载体之间存在着一定的相互作用。催化剂样品在各个 Ｔ Ｐ Ｒ 还原阶段的穆斯堡尔谱参数表明，多孔玻璃载体上至少存在着两种化学环境不同的氧化铁，其与载体的相互作用强度不同，并且在还原过程中分别对应不同温度下的反应： Ｆｅ２ Ｏ３ → Ｆｅ Ｏ→ Ｆｅ ．氧化铁在氧化铝或氧化硅载体上的还原生成 Ｆｅ２ ＋ 化合物，而在多孔玻璃载体上则有零价铁生成，表明多孔玻璃载体与氧化铁之间具有相对较弱的相互作用．

A series of porous glass supported iron oxides catalysts with various loading amount of Fe 2O 3 were prepared.The reduction of iron oxide supported on porous glass and the interactions between iron oxides and the support have been studied by using temperature programmed reduction combined with in situ Mssbauer spectroscopy.Three peaks were observed in the TPR profile of the samples,indicating the three reduction stages of the Fe 2O 3/porous glass samples and interaction between the porous glass support and iron oxides.The formation of FeO was also the evidence of the interaction between the porous glass and iron oxides.However,this interaction was not as strong as those between iron oxides and γ Al 2O 3 or SiO 2,since there was metallic iron formed during the reductions of Fe 2O 3/ porous glass. The measure results of in situ Mssbauer spectroscopy at various temperature programmed reduction stages show that two different states of Fe(Ⅲ) may exist on the porous glass support,corresponding to the reduction process of Fe 2O 3→FeO→Fe at different temperatures.