Ammonium Nitrate Temperature‐Programmed Decomposition on Fe–Zeolite Catalysts: Effect of Deposition Method

Abstract The N 2 O formation during NO x selective catalytic reduction by NH 3 is often attributed to NH 4 NO 3 intermediate decomposition. Thermal decomposition of NH 4 NO 3 has been extensively studied owing to the combination of its wide use as fertilizer and its dangerous properties. However, the decomposition of NH 4 NO 3 in the presence of a catalyst has generated less attention. The decomposition of NH 4 NO 3 may yield N x O y ‐type products such as NO, NO 2 , N 2 O, N 2 as well as HNO 3 and H 2 O. This work focuses on the emissions of N 2 O. The deposition of NH 4 NO 3 onto a Fe–zeolite catalyst was carried out by dry impregnation, by using a dilute solution of NH 4 NO 3 , and by a mechanical mixture. In the absence of catalyst, the release of N 2 O strongly depends on the conditions of the experiment (static or dynamic). The presence of a catalyst and the method of mixing ammonium nitrate into it affects its decomposition. Nitrogen formation is much more significant for the impregnated sample. For the mechanically mixed sample, the ammonium nitrate is mainly decomposed into N 2 O and NO 2 . N 2 O from ammonia oxidation was also detected in the presence of a catalyst.