###### Abstract
The deactivation of the Ru/\(\gamma\)-Al\({}_{2}\)O\({}_{3}\) catalyst caused by SO\({}_{2}\) is reported to be irreversible and attributed to the formation of stable sulfates on the catalyst surface. This phenomenon was confirmed through TPD-MS and TPR-H\({}_{2}\) experiments on the deactivated catalysts. The formed stable sulfates are difficult to remove, resulting in a permanent loss of catalyst activity. This mechanism suggests that the interaction of SO\({}_{2}\) with the catalyst surface leads to the formation of persistent sulfate complexes that block active sites, effectively eliminating the catalyst's ability to catalyze further reactions. Such deactivation is particularly significant in industrial applications, where catalyst regeneration can be costly or technically challenging [27; 28]. The Co-ZSM-5 catalyst shows inhibited activity in the presence of SO\({}_{2}\), while Cu-ZSM-5 is completely deactivated. SO\({}_{2}\) causes deactivation of the ex-Co-Rh, Al-HTIc catalyst, indicating its susceptibility to sulfur poisoning. However, surprisingly, SO\({}_{2}\) promotes N\({}_{2}\)O decomposition on the ex-FeZSM-5 catalyst, which may be related to the oxidation of SO\({}_{2}\) to SO\({}_{3}\), affecting the specific reaction mechanism on the catalyst surface. Differences in the reactions of the catalysts indicate a specific relationship between the nature of the catalyst material and its resistance to sulfur poisoning. This diversity highlights the need for further research on the mechanism of sulfur poisoning and identification of factors that can influence catalytic activity in the presence of sulfur compounds [29]. Pilot-scale studies on the deN\({}_{2}\)O catalyst presented in this article are crucial for understanding that it is extremely important not only to remove sulfur from the residual gas but also to minimize the presence of sulfur in the industrial environment, as this catalyst is highly sensitive even to trace amounts of sulfur. In our case, the periodic operation of boilers in another department, which serves as a source of sulfur in the air, leads to significant issues related to catalyst deactivation. The effectiveness of \(\mathrm{deN_{2}O}\) technology depends not only on the type of catalyst but also on the conditions of its installation, including the presence of contaminants. Given the limited research on the stability of \(\mathrm{deN_{2}O}\) catalysts under industrial conditions in the presence of \(\mathrm{SO_{2}}\), it is essential to study the rate of deactivation of these catalysts to better understand their long-term stability and to develop effective strategies for extending their lifetime in real industrial applications. Our research aims to fill this gap by providing new data on the impact of even small amounts of sulfur on the stability of \(\mathrm{deN_{2}O}\) catalysts, which is crucial for optimizing emission reduction technologies in industrial facilities [17; 29]. The decomposition of \(\mathrm{N_{2}O}\) is an exothermic, irreversible, first-order reaction (\(\mathrm{\Delta H_{2_{88}}=-163\ kJ/mol}\)), represented by the following equation: \(2\mathrm{N_{2}O}\to 2\mathrm{N_{2}}+\mathrm{O_{2}}\). In the presence of a catalyst, the activation energy is reduced, allowing the reaction to proceed at a lower temperature. The first step in the mechanism of \(\mathrm{N_{2}O}\) decomposition on the catalyst surface involves the breaking of the N-O-N bond, resulting in the formation of an \(\mathrm{N_{2}}\) molecule and the adsorption of oxygen on the active site of the catalyst (S, Equation (1)):  
\[\mathrm{N_{2}O}+\mathrm{S}\rightarrow\mathrm{N_{2}}+\mathrm{S}\ldots\mathrm{O }(\mathrm{surf_{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{ \mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{\mathrm{   \mathrm{     }}}}}}}}}}}}}}) \tag{1}\]  
The desorption of oxygen, leading to the regeneration of the active site, can proceed in two ways.