Infoscience

Journal article

Formation of the surface NO during N2O interaction at low temperature with iron-containing ZSM-5

Interaction of N2O at low temps. (473-603 K) with Fe-ZSM-5 zeolites (Fe, 0.01-2.1 wt%) activated by steaming and/or thermal treatment in He at 1323 K was studied by the transient response method and temp.-programmed desorption (TPD). Diffuse reflectance IR fourier transform spectroscopy (DRIFTS) of NO adsorbed at room temp. as a probe mol. indicated heterogeneity of surface Fe(II) sites. The most intensive bands were found at 1878 and 1891 cm-1, characteristic of 2 types mononitrosyl species assigned to Fe2+(NO) involved in bi- and oligonuclear species. Fast loading of at. O from N2O on the surface and slower formation of adsorbed NO species were obsd. The initial rate of adsorbed NO formation was linearly dependent on the concn. of active Fe sites assigned to bi- and oligonuclear species, evolving oxygen in the TPD at around 630-670 K. The maximal coverage of a zeolite surface by NO was estd. from the TPD of NO at .apprx.700 K. This allowed the simulation of the dynamics of the adsorbed NO formation at 523 K, which was consistent with the expts. The adsorbed NO facilitated the at. oxygen recombination/desorption, the rate detg. step during N2O decompn. to O2 and N2, taking place at temps. >=563 K. [on SciFinder (R)]

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