## 3 Results and Discussion
### Catalytic Activity
These results are presented in Table 2.  
The relationship between N\({}_{2}\)O conversion efficiency and residual gas flow rate at temperatures of 440 \({}^{\circ}\)C and 420 \({}^{\circ}\)C is depicted in Figure 2. This graphical representation elucidates how variations in flow rate affect the fresh de\(\text{k}_{2}\)O catalyst's efficiency under differing thermal conditions, providing a detailed framework for optimizing operational parameters in the N\({}_{2}\)O reduction process. These insights are pivotal for advancing the understanding of process dynamics and for refining reactor operating conditions to achieve the maximum conversion efficiency. Further attempts to decrease the flow rate, based on the earlier conclusion that lower flow rates should enhance conversion, also failed to produce the desired outcome--no N\({}_{2}\)O conversion was achieved (samples no. 4.26-4.28 in Table 2). Without any changes to the operational conditions, the N\({}_{2}\)O concentration at the inlet equaled that at the outlet, indicating a complete lack of conversion. Consequently, the catalyst was deemed deactivated. Further experimental data are presented in Table 3. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \(\mathbf{C_{0,N2O}}\) & \multirow{2}{*}{\(\mathbf{X_{N2O}}\) [\%]} & \multicolumn{2}{c}{**Flow**} & \multirow{2}{*}{\(\mathbf{T_{inlet}}\) [\({}^{\circ}\)C]} & \multirow{2}{*}{\(\mathbf{T_{outlet}}\) [\({}^{\circ}\)C]} \\  & [ppm] & & & & \\ \hline
4.29 & 120.1 & \(-\)0.7 & 120 & 437.4 & 446.2 \\
4.30 & 116.2 & \(-\)0.7 & 100 & 435.2 & 444.4 \\
4.31 & 111.5 & \(-\)0.6 & 60 & 432.8 & 445.2 \\
4.32 & 112.1 & \(-\)0.6 & 39 & 432.1 & 444.8 \\
4.33 & 118.3 & \(-\)0.1 & 19 & 438.4 & 445.1 \\
4.34 & 88.1 & \(-\)5.9 & 11 & 422.9 & 452.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Efficiency of N\({}_{2}\)O conversion in further examination during pilot-scale study. The results presented in Table 3 contain negative conversion values, which result from measurement errors rather than the actual properties of the process. Conversion cannot take negative values, and these results should be interpreted as discrepancies related to inaccuracies in the measurements of N\({}_{2}\)O concentrations before and after the reactor. These values indicate that the actual conversion was zero, meaning that the conversion did not occur, suggesting complete deactivation of the catalyst. The conversion (X) was calculated according to the formula in Equation (4):  
\[X=\frac{C_{0,N_{2}O}-C_{N_{2}O}}{C_{0,N_{2}O}} \tag{4}\]  
where C\({}_{0,N_{2}O}\) represents the N\({}_{2}\)O concentration at the reactor inlet, which under operating conditions was equal to the gas concentration in the installation's stack within the margin of measurement error, due to the minor time delay resulting from the gas flow. This means that there are no significant differences in concentration between the measurement point before the reactor and the stack. Therefore, the negative conversion values result from minor measurement errors and indicate that the reaction did not occur, which in practice means complete deactivation of the catalyst. A stability study of the same catalytic bed was reported elsewhere. The catalyst was proved to be resistant to contaminants, such as H\({}_{2}\)O and O\({}_{2}\), which do not affect its performance. Only the concentration of NO\({}_{\mathrm{x}}\) impacted the conversion, causing a decrease of about 10% when NO\({}_{\mathrm{x}}\) concentration increased within the range of 500 to 2700 ppm. However, this process is reversible, as the N\({}_{2}\)O conversion gradually returns to its initial level after the NO\({}_{\mathrm{x}}\) is removed [35]. Despite a thorough analysis of the process, the specific cause of the catalyst deactivation could not be identified.