甲醇氨氧化制氢氰酸的铁钼催化剂活性组分的研究

采用X射线衍射、IR、M(?)ssbauer、ESR和ESCA等方法研究了甲醇氨氧化制氢氰酸的铁钼催化剂活性组分与催化活性的关系.X射线衍射和IR研究指出,催化剂中的铁和钼是以Fe_2(MoO_4)_3、MoO_3和a-Fe_2O_3存在.Fe_2(MoO_4)_3的相对含量与活性随Fe/Mo的变化呈峰形对应关系.M(?)ssbauer、ESR和ESCA分析表明,铁是以Fe~(3+)存在,但有两种配位,一种是Fe_2(MoO_4)_3中的八面体配位,另一种可能是Fe_2O_3·xMoO_3(x<3)的不完善配位.前者是基本活性组分,和后者一起完成选择氧化的功能.

A Study on the Active Components of Iron-Molybdenum Oxide Catalysts Used in Ammoxidation of Methanol for HCN Syntheses

The active components of a series of Iron-Molybdenum oxide catalysts andtheir correlations with catalytic activity in ammoxidation of methanol were investigated by X-Ray diffraction, IR, Mossbauer, ESR and ESCA techniques. X-Ray diffraction and IR studies indicated that Fe and Mo ions were present as Fe2(MoO4)3, MoO3 and α-Fe2O3 in the catalysts. The plots of the relative content of Fe2(MoO4)3 and activity versus Fe/Mo showed corresponding peak shapes. Mossbauer, ESR and ESCA analysis showed that Fe existed in Fe3+ states at two different sites, one with octahedral coordination in Fe2(MoO4)3, the other with imperfect coordination in Fe2O3,xMoO3 where x<3. The former may be the basic active component, performing the function of selective oxidation together with the latter.