氧化铈在非贵金属氧化物催化剂中的作用 Ⅵ.CuFeCeO催化剂的结构与热稳定性

Role of Ceria in Non Precious Metal Oxide CatalystsⅥ. Structure and Thermostability of Cu Fe Ce O Catalysts

采用ＸＲＤ， 顺磁共振（ＥＳＲ） ， Ｍｏｓｓｂａｕｅｒ 和程序升温还原（ＴＰＲ） 技术对负载型ＣｕＦｅＯ（ Ⅰ） ，ＣｕＦｅＣｅＯ（ Ⅱ） 催化剂的固相结构及热稳定性进行了研究。结果发现，（ Ⅰ） 中主要存在Ｆｅ２ＣｕＯ４ ，ＣｕＯ 和颗粒度小于１３ ｎｍ 的Ｆｅ２Ｏ３ 相。随着焙烧温度的升高，ＣｕＯ 晶相逐渐消失，Ｆｅ２ＣｕＯ４ 的晶相长大。（ Ⅱ） 中Ｃｅ的存在， 能提高Ｃｕ２＋ 的浓度， 抑制ＣｕＯ 和Ｆｅ２ＣｕＯ４ 晶相的生成， 能消除催化剂中ＣｕＯ 与ＦｅＯ中氧在还原时的差异， 但抑阻Ｆｅ２Ｏ３ 晶相生成的效果不明显。在８００ ℃的高温环境中，Ｃｅ 的存在能有效地防止Ｆｅ２Ｏ３ 颗粒的长大， 提高催化剂中活性相的热稳定性以防止烧结， 同时使催化剂的低温还原性能有所提高。

The solid structures and thermostabilities of Cu Fe O(Ⅰ) and Cu Fe Cu O(Ⅱ) supported on alumina were studied by XRD, ESR, Mossbauer and TPR techniques. The study indicates that there are Fe 2CuO 4, CuO and α Fe 2O 3 phases in (Ⅰ) with the granula of less than 13 nm. With rising the pretreatment temperature of catalyst, the crystallite of Fe 2CuO 4 in the catalysts grows up and that of CuO disappears gradually. The presence of Ce can increase the concentration of Cu 2+ and inhibit the crystal growth of CuO and Fe 2CuO 4 in the catalysts except that of Fe 2O 3, and make the reduction of the oxygen of Fe O as easily as the oxygen in Cu O. At 800 ℃, the crystal growth of Fe 2O 3 in (Ⅱ) is lower than that in (Ⅰ). CeO 2 in (Ⅱ) inhibits the growth of Fe 2O 3 phase effectively, and enhances the thermostability of catalysts to avoid the active elements in catalysts sintering.