Identification of Fe2(μ-O) and Fe2(μ-O)2 sites in Fe/ZSM-35 by in situ resonance Raman spectroscopy

The structure of the active iron site in Fe/ZSM-35 was investigated by in situ resonance Raman spectroscopy combined with Mössbauer spectroscopy and DFT calculations. In situ UV resonance Raman spectra coupled with 57Fe Mössbauer spectra suggest that the active Fe site for N2O decomposition is an Fe2(μ-O) site, characterized by a Raman band at 875 cm−1. In situ visible resonance Raman spectra reveals the formation of an Fe2(μ-O)2 site with a feature Raman band at 730 cm−1 upon N2O reacts with the Fe2(μ-O) site. The Raman band intensity at 730 cm−1 is decreasing after exposing the Fe2(μ-O)2 site to CH4 due to the formation of methoxide species which mimics the biocatalysis of soluble methane monooxygenase (sMMO).