气相色谱法研究配位化合物的热稳定性——Ⅸ.Fe2(C2O4)3—HZSM-5和Fe2(C2O4)3—HY的热分解

STUDIES ON THERMAL STABILITIES OF COORDINATION COMPOUNDS BY GAS CHROMATOGRAPHY——Ⅸ.THERMAL DECOMPOSITION OF Fe2(C2O4)3—HZSM-5 AND Fe2(C2O4)—HY

本文研究了草酸铁(Ⅲ)负载在 HZSM-5和 HY 沸石上的性质和热分解.草酸铁(Ⅲ)在沸石表面发生离解吸附,CO与表面的 Al 配位,热分解时产生β峰.草酸铁(Ⅲ)与 HZSM-5沸石作用较弱,在氢气中500℃时的还原产物为α-Fe,而Fe(CO)—HY 体系在氢气中500℃时除得到α-Fe 外,还有少量高分散的零价铁和部分难以还原的铁离子.

Some properties and thermal decomposition of Fe(Ⅲ)oxalate supported on HZSM-5 and HY zeolites have been studied by GC,IR and M(?)ssbauer spectral methods.Acco-rding to the results of the GC experiments,thermal decomposition of the unsupported Fe(Ⅲ)oxalate took place in two steps as indicated by peakα(giving CO)and peakγ(yielding CO and CO),but Fe(Ⅲ)oxalate supported on zeolites gave additional peak(producing CO and CO)as a result of the interaction between COand Al.The M(?)ssbauer parameters of Fe(CO)—HZSM-5 system were similar to those of Fe(CO)·5HO,indicating that the effect of HZSM-5 was fairly weak.However,the spectrum of Fe(CO)—HY consisted of two doublets,one had a smaller⊿and another a larger⊿.For part of Fe(Ⅲ),there could be no direct interaction between the metal and the support,giving a smaller⊿,but for the other part of Fe(Ⅲ),the larger⊿might be due to the coordination of Fe(Ⅲ)on the surface of the support during impregnation.At 240℃most of Fe(Ⅲ)of Fe(CO)—HZSM-5 was reduced,yielding COand FoCO.However for Fe(CO)—HY,as much as 64%Fe(Ⅲ)could not be reduced at the same temperature.At 500℃Fe(CO)—HZSM-5 producedα-Fe in hydrogen,but for Fe(CO)—HY,the decomposition products consisted of surface Fe(Ⅲ)and Fo(Ⅱ)(?)xides,α-Fe and highly dispersed Fe(0).It confirmed the fact that the interaction between iron cations and the surface of HY zeolite led to dispersion of the decomposition products on the support and made part of iron cations difficult to be reduced.