Redox properties of substituted iron in low-iron content Fe-MFI (Si/Fe≈200) and Fe-MCM-41 (Si/Fe=137) samples were compared by in situ Mössbauer spectroscopy (in vacuum, H2, CO, N2O, at 300 K <T< 600 K). The Fe3+ ↔ Fe2+ conversion may proceed reversibly in both hosts. In MFI the rigid structure of the framework is manifested: framework-substituted ferric ions are not reduced, the Fe3+ to Fe2+ reduction proceeding only on extraframework ions. The MCM-41 host is more flexible, allowing various Fe2+ coordinations to occur in the pore wall.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Condensed Matter Physics
- Physical and Theoretical Chemistry