Iron-exchanged FAU zeolites: Preparation, characterization and catalytic properties for N2O decomposition

New Fe-FAU zeolitic catalysts made from large channel zeolite matrix FAU by a simple wet ion exchange method show an excellent performance in N2O catalytic decomposition. The ion exchange process was discussed in detail and the optimal conditions for wet ion exchange were proposed. The formation of various iron sites in Fe-FAU samples (isolated Fe ions, oligonuclear clusters and Fe2O3 nanoparticles) during preparation process was extensively investigated by means of UV–vis spectra, FTIR spectra of NO adsorption, TEM images, H2-TPR and 27Al MAS-NMR spectra. We have found that Fe(III)-FAU catalysts more effectively decompose N2O with/out NO-assistance than other Fe-zeolite (such as Fe-MFI) catalysts prepared in the same way. Comprehensive understanding of the structure properties and the catalytic performance suggests that different iron sites in Fe-FAU make different contributions to N2O thermal decomposition and that isolated/oligonuclear iron species contribute more due to their high accessibility towards N2O. In addition, the high durability of Fe-FAU catalysts is proposed to account for the particular interactions between iron species and zeolite framework.

Large-channel zeolite FAU can be readily loaded with ferric ions in a high dispersion state by simple wet ion exchange. Such an Fe(III)-zeolite catalyst shows a higher activity and a longer durability for N2O thermal decomposition than Fe-MFI zeolite catalysts, presumably because of the attachment of various Fe(III) species onto the zeolite framework.Figure optionsDownload as PowerPoint slide