## 4 Conclusions  
This work describes the influence of the different steps involved in the preparation of a Mo/ZSM-5 catalysts for dehydroaromatization of methane. Both the Mo incorporation method, e.g., by incipient wetness impregnation (IW) or by solid state ion exchange (SSR), and the calcination conditions, under static or dynamic air atmosphere, determine the size and location of the starting MoO\({}_{3}\) particles, and lead to catalysts with different micropore volume and BAS density. Thus, when the metal is added by means of IW the MoO\({}_{3}\) clusters are better dispersed on the external surface of the zeolite and a larger proportion of Mo species have migrated into the zeolite micropores, independently of the calcination procedure. However, calcination in air flow favors the formation of cationic Mo species in zeolite ion exchange positions, as suggested by the decrease of the BAS density, and in Mo species easily reducible, not only from Mo\({}^{6+}\) to Mo\({}^{4+}\), but also from Mo\({}^{4+}\) to Mo\({}^{0}\). On the other hand, Mo incorporation by SSR results in a poor dispersion and large MoO\({}_{3}\) clusters, especially when the samples are calcined in a muffle under static conditions. Calcination in air flow favors dispersion of the MoO\({}_{3}\) particles, but in this case the optimum Mo speciation is achieved by means of a pretreatment increasing temperature up to in a N\({}_{2}\) flow. Regarding the performance of the different catalysts for methane dehydroaromatization, the initial conversion obtained with all samples is comparable and close to the equilibrium conversion at the reaction temperature of 973 K. However, the samples obtained by dynamic calcination in air flow, present a lower deactivation rate with TOS and higher yield to the desired aromatic hydrocarbons and, in particular, to benzene, independently of the Mo incorporation method. The catalyst performance of MoZ5-SSR-DC, prepared by solid ion exchange, can be further improved by means of the N\({}_{2}\) pretreatment, an improvement that has been directly related to the increased migration of the Mo species into the zeolite structure. Important benefits are observed, not only in catalyst life and yield to aromatics, but also in a significantly lower coke yield. The following are available online at [[https://www.mdpi.com/article/10.3390/app11125465/s1](https://www.mdpi.com/article/10.3390/app11125465/s1)]([https://www.mdpi.com/article/10.3390/app11125465/s1](https://www.mdpi.com/article/10.3390/app11125465/s1)), Figure S1. FESEM images of the parent ZSM-5 zeolite, Figure S2. N2 adsorption isotherms of the parent ZSM-5 zeolite and the Mo-loaded catalysts. (A) Samples prepared by incipient wetness impregnation (IW); (B) samples prepared by solid state reaction (SSR), Figure S3. SEM images using a secondary electron detector (A) and a backscattered electron detector (B) for the MoZ5-SSR-SC catalyst after being analyzed by H2-TPR, Figure S4. PXRD patterns of the Mo/ZSM-5 catalysts prepared by solid state ion exchange reaction (SSR). The most characteristic peaks related to  
Figure 7: Estimated yield to coke versus time on stream (TOS) for the catalysts: MoZ5-SSR-DC (a), MoZ5-SSR-SC-N\({}_{2}\) (\(\blacktriangle\)), MoZ5-SSR-DC (\(\blacksquare\)) and MoZ5-SSR-DC-N\({}_{2}\) (\(\boxbox\)), at 973 K and atmospheric pressure (w/F = 16 g\(\cdot\)h/mol). the presence of MoO3 are marked with a dotted line, Figure 55. H2-TPR profiles for the Mo/ZSM-5 catalyst prepared by solid state ion exchange reaction calcined in static conditions (A), MoZ5-SSR-SC (black line) and MoZ5-SSR-SC-N2 (grey line), and in dynamic conditions (B), MoZ5-SSR-DC (black line) and MoZ5-SSR-DC-N2 (grey line). Conceptualization, M.T.P., C.M. ; methodology, M.T.P. ; investigation, M.T.P. ; writing--original draft preparation, M.T.P., C.M. ; writing--review and editing, F.J.L., M.M., C.M. ; supervision, F.J.L., C.M. ; project administration, M.M., C.M. ; funding acquisition, M.M., C.M. All authors have read and agreed to the published version of the manuscript.