The products of the reaction between 15NO and 14NH3 over V2O5/TiO2 and α-Cr2O3 catalysts in the absence of oxygen have been determined by mass spectrometry and Fourier transform infrared spectroscopy. With both catalysts 14N15N comprises approximately two-thirds of the nitrogen-containing products. Very surprisingly, 15NH3 makes up about one-half the remainder. This has significant implications for the likely mechanism of the SCR reaction in the absence of oxygen. Formation of 15NH3 by direct exchange of both hydrogen and oxygen between 14NH3 and 15NO molecules can be ruled out since no 14NO is produced. It seems that 15NO is broken down to separate 15N and oxygen species on reduced sites and that 15NH3 can then be made by reaction of the 15N species with water. It is possible that the nitrogen-containing species is an NH group. With V2O5/ TiO2 the only remaining product is 14N15NO. However, this is largely replaced by doubly labeled products, 14N2, 15N2, and 15N2O, when using α-Cr2O3.
|Number of pages||4|
|Journal||Journal of Physical Chemistry|
|Publication status||Published - 1993|