摘要
通过ＸＲＤ，ＢＥＴ和ＸＰＳ表征及反应活性测定表明，ＣＯ高温变换催化剂中加入的助剂ＣｒＯ３在制备及还原过程中，能进入Ｆｅ３Ｏ４晶格，使晶胞参数增大、晶粒度变小、分散度提高、比表面积和孔容积增大、孔结构改善而提高催化剂活性和稳定性．加入的ＣｒＯ３有７６％以Ｃｒ３＋形态存在于尖晶石的正八面体空隙中，２４％以Ｃｒ６＋形态存在于正八面体和正四面体空隙中．氧化铬不仅起到结构助剂作用，可能还起到电子助剂作用．加入的Ｃｒ２Ｏ３不进入Ｆｅ３Ｏ４晶格而以独立相存在，不起助剂作用．
The effect of CrO 3 on the catalyst for carbon monoxide high temperature shift reaction was studied by means of XRD, BET, XPS and catalytic activity measurement. It was shown that CrO 3 entered the lattice of Fe 3O 4 during preparation or reduction process of the catalyst. In this case, lattice parameter increased, crystallite size decreased, dispersion of the active phase was improving, surface area and pore volume increased, then pore structure refined, resulting in the optimization of catalytic activity and stability of the catalyst. It was also found that 76%CrO 3 formed Cr 3+ existing in the octahedral interstitialcy of Fe 3O 4 lattice, while 24%CrO 3 formed Cr 6+ existing in its octahedral or tetrahedral interstitialcy. CrO 3 acted as a structural and electronic promoter in the catalyst. Cr 2O 3 cannot act as CrO 3, because it is a stable phase and not easy to enter Fe 3O 4 lattice.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
1998年第5期402-405,共4页
基金
国家自然科学基金
关键词
铁铬系
催化剂
高温变换
一氧化碳
氨合成
Iron chromium catalyst, High temperature shift reaction, Chromia, Structure, Property
