## 3 Results and Discussions  
### Characterization Results  
Incorporation of 6 wt. % of molybdenum was confirmed by ICP for all of catalysts resulting in a Mo/Al molar ratio of 0.5 (see Table 1), independently of the metal incorporation method (incipient wetness impregnation, IW, or solid state reaction, SSR) or the calcination procedure (muffle or fixed-bed reactor). This Mo/Al molar ratio was reported by [PERSON] et al. [50] to be the optimum for activating the methane molecules on the active Mo species and converting them to aromatics on the BAS. The preservation of the zeolitic structure after Mo incorporation was confirmed by powder XRD (see Figure 1). It is important to note that the PXRD patterns of the samplesprepared by solid state reaction, MoZ5-SSR-SC and MoZ5-SSR-DC, present some peaks assigned to MoO\({}_{3}\) at 12.3\({}^{\circ}\), 25.7\({}^{\circ}\), 27.4\({}^{\circ}\) and 39\({}^{\circ}\), indicating the presence of larger oxide agglomerates. These peaks are more intense when the samples were obtained by muffle calcination (MoZ5-SSR-SC). However, no diffraction peaks corresponding to MoO\({}_{3}\) were detected in the samples prepared by incipient wetness (IV), independently of the calcination procedure, indicating a better dispersion of the metallic species. The presence of large MoO\({}_{3}\) particles in the two samples prepared by SSR, MoZ5-SSR-SC and MoZ5-SSR-DC, is confirmed by FESEM employing a backscatter electron (BSE) detector (see Figure 2). The Mo-loaded ZSM-5 samples present lower BET surface area, micropore surface area and volume, (see Table 1 and isotherms in Figure S2 in the Supplementary Materials) and a lower amount of total Brensted acid sites (see Table 2) as compared to the parent zeolite. This fact could be related to the partial blocking of the zeolite microporovosity by the MoO\({}_{3}\) particles and to the migration of the Mo species into the channels during the calcination step, as previously described [46; 54; 60], a migration that has been directly related to the presence of Brensted acid sites [50; 54; 58; 59; 62; 63; 74]. As expected, the metal incorporation procedure has an important influence on the textural and acidic properties of the final catalysts, and the higher the metal dispersion according to PXRD and FESEM, the larger the reduction of micropore surface and BAS density, in good agreement with previous publications [49; 69]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{3}{c}{**ICP**} & \multirow{2}{*}{\begin{tabular}{c} **S** **bet** \\ **(m\({}^{2}\)/g)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **S** **micro** \\ **(m\({}^{2}\)/g)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **V** **micro** \\ **(cm\({}^{3}\)/g)** \\ \end{tabular} } \\ \cline{2-2} \cline{6-6}  & **Si/Al** & & & & & \\ \hline Z5 (TZP302A) & 10.0 & — & — & 368 & 355 & 0.17 \\ \hline MoZ5-IW-SC & 10.5 & 0.5 & 6.0 & 270 & 257 & 0.12 \\ MoZ5-IW-DC & 9.9 & 0.5 & 6.1 & 263 & 246 & 0.12 \\ MoZ5-SSR-SC & 10.3 & 0.5 & 6.4 & 292 & 275 & 0.13 \\ MoZ5-SSR-DC & 10.2 & 0.5 & 6.3 & 276 & 260 & 0.13 \\ \hline MoZ5-SSR-SC-N2 & 10.3 & 0.5 & 6.4 & 254 & 241 & 0.12 \\ MoZ5-SSR-DC-N2 & 10.2 & 0.5 & 6.3 & 237 & 221 & 0.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Physico-chemical properties of the Mo/ZSM-5 catalysts. Figure 1: PXRD patterns of the Mo/ZSM-5 catalysts. The most characteristic peaks related to the presence of MoO\({}_{3}\) are marked with a dotted line. Figure 2: FESEM images of the Mo/ZSM-5 catalysts by a field emission scanning electron microscopy employing a backscatter electron detector (BSE): (**A**) MoZ5-IW-SC, (**B**) MoZ5-IW-DC, (**C**) MoZ5-SSR-SC, (**D**) MoZ5-SSR-DC, (**E**) MoZ5-SSR-SC-N2, (**F**) MoZ5-SSR-DC-N2. Since the dispersion of molybdenum depends on the Mo incorporation method, it may also interfere in the nature, the accessibility and the reducibility of the Mo species.