Fe—Si—ZSM—12分子筛的表征

本文用红外光谱研究了Fe-Si-ZSM-12分子筛,观察到其结构单元的骨架振动谱带在545cm~(-1)、580cm~(-1)和630cm~(-1),而表示Si—O—Fe键的对称伸缩振动谱带在660cm~(-1)和780cm~(-1),且随铁含量增加向高波数位移。Fe-Si-ZSM-12分子筛的穆斯堡尔谱的结果表明,骨架铁的IS值很小,IS=0.086(-0.17)mm/s,且QS=0.0mm/s,这明显不同于非骨架铁IS=0.53mm/s。在Fe-Si-ZSM-12分子筛的ESR谱图上,观察到骨架铁的顺磁信号(g=4.3),样品焙烧后顺磁信号减弱,骨架铁向非骨架位迁移。IR、Mossbauer、ESR结果证明,Fe~(3+)进入了骨架。

THE CHARACTERIZATION OF Fe-Si-ZSM-12 ZEOLITE

The IR spectra of pramework vibration for Fe-Si-ZSM-12 zeolite indicated that the absorption bands of its building units were at 545,580 and 630cm~(-1),while those of Fe-O-Si bonds were at 660 and 780 cm~(-1) which shifted toward higher values with increacing iron conten(?).The Mossbauer spectra for Fe-Si-ZSM-12 zeolite gave an IS value of 0.086 (-0.17)mm/s and QS value of 0.0mm/s for iron at framework;while for iron in channel IS was 0.53 mm/s and QS was 0.0mm/s.A signal of ESR was observed for iron at framework with g=4.3. When the sample was calcined, Fe~(3+) was moved away from the framework, lowering the ESR signal of framework Fe~(3+). The results of IR, Mossbauer and ESR spectroscopies showed that Fe~(3+) was isomorphously substituted at the tetrahedral positions.