FTIR study of the interaction of nitric oxide with Fe-ZSM-51

The temporal behavior of infrared spectra obtained during NO adsorption on oxidized and reduced Fe-ZSM-5 at -100, 0 degreesC, and ambient temperature is reported. The band assignment is made based on the adsorption of labeled molecules. Bands near 1838 and 1886 cm(-1) (mononitrosyl Fe2+(NO) species) form quickly and remain invariant. Bands at 1922 and 1813 cm(-1) (dinitrosyl Fe2+(NO)(2)) together with a band at 1750 cm(-1) (another mononitrosyl species) gradually become more intense for hours. Purging with He at 0-500 degreesC leads to a gradual decrease in the intensity of all the bands. Mononitrosyl bands near 1886 and 1838 cm(-1) are the most stable. The features of the IR spectra of adsorbed NO suggest the presence of dispersed Fe oxide clusters in the zeolitic pore network in addition to Fe2+ ions in cationic positions of ZSM-5.