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Abstract: In the first part of this thesis work, a series of tetrabutyl ammonium (TBA) salts of Keggintype polyoxoanions with V included instead of W (TBA4PW11V1O40 and TBA5PW10V2O40) and Mo(TBA4PMo11V1O40 and TBA5PMo10V2O40) as added atoms were prepared by a hydrothermal method. These synthesized materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance UV-Vis (DRS UV-Vis), thermogravimetric analysis (TGA), CHN elemental analysis (EA), inductively coupled plasma spectrometry (ICP-MS) and N2 physisorption techniques to evaluate their physicochemical/textural properties and correlate them with their catalytic performances. According to FT-IR and DRS UV-Vis, (PVXW(Mo)12-XO40)(3+X)-anions are the main species present in TBA salts. In addition, CHN-EA and ICP-MS revealed that the desired stoichiometry was obtained. In summary, the results showed that the proposed catalysts were successfully synthesized, preserving the Keggin structure and confirming the successful inclusion of V in the structure, and in the expected number. Then, in both Mo and W series, it was found that after substitution of the addenda atoms by V, there was an improvement in catalytic activity concerning the unsubstituted atoms. Subsequently, their catalytic activities were studied in the liquid-phase, aerobic oxidation of benzyl alcohol to benzaldehyde at 5 bar O2 and 170℃. Regardless of the nature of the addition atom, the catalytic activity increased with the number of V in the Keggin anion structure. For both series of catalysts, the TBA salts of polyoxometalates with the highest degree of V substitution (TBA5PMo10V2O40 and TBA5PW10V2O40) showed the highest activity. The maximum benzyl alcohol conversion obtained was 93% and 97% using (TBA)5PMo10V2O40 and (TBA)5PW10V2O40 as catalysts, respectively. In all cases, the selectivity towards benzaldehyde was higher than 99%. In the second part of this thesis work, a study was carried out for the optimization of the operational conditions in the catalytic oxidation reaction of phenethoxybenzene with (TBA)5[PMo10V2O40] catalyst. The optimization was carried out in two stages, the first one consisted of the determination of the variables A fractional factorial design of 4 variables was used, which were temperature (T, ℃), time (t, h) O2 pressure (PO2, bar) and catalyst mass (Mcat, mg).Statistical validation of the model using an ANOVA analysis of the model, showed to be significant for 95% confidence (P ?0.05) and presents a good fit to explain the variability of the response from the variables, with an R2 of 0.984. The statistically significant variables according to the model are temperature (X1) and time (X2), with P-values ?0.05. For the second stage, a central circumscribed composite design (CCC) was used for three variables (T, t and Mcat) and three levels (with star points). The model was analyzed and statistically validated by ANOVA, which was significant for 95% confidence and had an R2 of 0.948, ensuring an adequate fit to the data. As a result, the significant independent variables (P ? 0.05) were the quadratic terms temperature (X12), time (X22), and catalyst mass (X32). The optimum conditions to obtain 77.0 % phenethoxybenzene conversion were a temperature of 137℃, time of 3.5 h and catalyst mass of 200 mg. Finally, the experimental validation of the mathematical model yielded an experimental conversion value (%) of 76.7+ -0.2. Furthermore, depolymerization was confirmed by GPC with the decrease of the Mw molar mass distribution from 7.34 kDa to 1.97 kDa, a decrease of the PDI polydispersity index from 6 to 3 was also detected. Also, the successful cleavage of the β-O-4 bond was verified by GC-MS analysis of the reaction products. Finally, the optimization approach through the experimental design of the operational variables for the catalytic oxidation reaction of phenethoxybenzene with the Keggin-type catalyst(TBA)5[PMo10V2O40] proved to be a useful tool in the design of a catalytic system for the oxidation of phenethoxybenzene with Keggin-type polyoxometalate catalysts, with a view to the valorization of lignin. The characteristics studied above, clearly demonstrate the effects of the structural features of the Keggin-type POMs on the catalytic activity in the selective catalytic oxidation reaction of lignin model substrates.