N 2 O Decomposition over Fe‐ZSM‐5 Studied by Transient Techniques

N 2 O decomposition to gaseous N 2 and O 2 catalyzed by a commercial Fe‐ZSM‐5 has been studied by different transient techniques: (i) via the transient response methods at ambient pressure, (ii) via the temporal analysis of products (TAP) reactor under vacuum, and (iii) by temperature‐programmed desorption (TPD) under vacuum. The catalyst was activated in He at 1323 K. Two main steps can be distinguished within the transient period of N 2 O decomposition under constant N 2 O feed at 603 K: the first step consists of molecular N 2 formation and surface atomic oxygen (O) Fe . It follows a period of stoichiometric N 2 O decomposition to gaseous N 2 and O 2 with increasing conversion until steady state is reached. The observed rate increase is assigned to a slow accumulation on the surface of NO x,ads species formed from N 2 O and participating as co‐catalyst in the N 2 O decomposition. The NO x,ads species accelerates the atomic oxygen recombination/desorption, which is the rate‐determining step of N 2 O decomposition. The formation and accumulation of NO x,ads species during N 2 O interaction with the catalyst was confirmed by TAP studies. The amount of NO x,ads was found to depend on the number of N 2 O pulses injected into the TAP reactor. In the presence of adsorbed NO x on the catalyst surface (NO x,ads ) the desorption of dioxygen is facilitated. This results in a shift of the oxygen desorption temperature from 744 K to considerably lower temperatures of 580 K in TPD experiments. Pulses of gaseous NO had a similar effect leading to the formation NO x,ads , thus facilitating the oxygen recombination/desorption.