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研究了Fe在Ferrozeosilite(在非碱性介质中合成的Fe-ZSM-5)分子筛中的存在状态。XPS和Mossbauer谱表明,Fe以Fe(Ⅲ)和Fe(Ⅱ)两种价态共存于Ferrozeosilite分子筛骨架中,同时伴有少量非骨架Fe的存在。用EPR研究了Ferrozeosilite分子筛的生成过程及灼烧后各种状态Fe的变化和迁移行为。Fe对ZSM-5沸石骨架的同晶取代过程在EPR谱中表现为g=4.3处顺磁共振信号的增强。灼烧后样品EPR谱中g=4.3处信号的减弱和g=2.3处宽谱的出现源于骨架Fe在灼烧过程中的部分迁移行为。EPMA对抛光后的分子筛晶体剖面分析表明,Fe原子在Ferrozeosilite晶体中的分布是内层富集。
The existence of Fe in zeolite Ferrozeosilite (Fe-ZSM-5 synthesized in non-alkaline medium) was investigated. XPS and Mossbauer spectra show that Fe coexists with Ferrozeosilite molecular sieve framework with Fe (Ⅲ) and Fe (Ⅱ) valences, accompanied by a small amount of non-framework Fe. The formation process of Ferrozeosilite zeolite and the change and migration of various Fe species after burning were studied by EPR. The isomorphous substitution of Fe for the ZSM-5 zeolite framework appears as an enhancement of the paramagnetic resonance signal at g = 4.3 in the EPR spectrum. The weakening of signal at g = 4.3 and the appearance of broad spectrum at g = 2.3 in the EPR spectra of the burned samples result from the partial migration of Fe in the framework during the burning process. EPMA analysis of the polished molecular sieve crystals shows that the distribution of Fe atoms in the ferrozeosilite crystals is the enrichment of the inner layer.