## 1 Introduction
Among these, the material Au-Cu/SiO\({}_{2}\) with an Au/Cu weight ratio = 4 was the best catalyst, showing 98% of BzOH conversion and >99% of selectivity towards BzD at 313 \({}^{\circ}\)C. Similarly, [PERSON] and co-workers [13] used Au-Pd/TiO\({}_{2}\) catalysts in the liquid-phase oxidation of BzOH under O\({}_{2}\) constant pressure. The material containing 2.5 wt.% of each metal showed good performance under mild conditions (\(p\)O\({}_{2}\) = 0.2 MPa and \(T\) = 100 \({}^{\circ}\)C) when compared to their monometallic analogs, exhibiting 75% of BzOH conversion and 92% of selectivity towards BzD after 8 h. Even though the good redox activity of metal nanoparticles in the activation of oxygenated species to form peroxo/hydroperoxo intermediates via hydride transfer and dehydrogenative pathways is well known [17], the combination with other metallic nanoparticles seeks the enhancement of the catalyst conversion, selectivity, and durability. [PERSON] and co-workers [14] modified ZSM-5 zeolites with sodium hydroxide to investigate their activity in the liquid-phase oxidation of BzOH with hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)/BzOH ratio = 1.3) at reflux conditions. All obtained materials presented a higher Lewis acidity and external surface area after the alkali-treatment. The best catalyst was obtained after 0.5 h of the latter process, showing 53% of BzOH conversion and 86% of selectivity towards BzD. Both Lewis and Brensted acid-base sites can play important roles in the efficiency of this process by performing a dehydrogenative step in the methylene carbon that allows BzOH oxidation [14,18]. [PERSON] and co-workers [16] synthesized a mesoporous hybrid material based on the interaction between the heteropolyacid H\({}_{3}\)PW\({}_{12}\)O\({}_{40}\) and \(N^{\prime\prime}\)-(3-amino-2-hydroxypropyl)-\(N\),\(N\),\(N^{\prime}\),\(N^{\prime}\)-tetramethylguanidinium chloride (TMGHACI), an ionic liquid. The catalyst, [TMGHAL\({}_{2,4}\)H\({}_{0,6}\)PW\({}_{12}\)O\({}_{40}\), was tested in the water-mediated liquid-phase oxidation of BzOH with H\({}_{2}\)O\({}_{2}\) to test the reaction viability in a triphasic system. The catalyst gave 98% of BzOH conversion and 94% of selectivity towards BzD at 90 \({}^{\circ}\)C after 6 h. The interaction between the heteropolyanion PW\({}_{12}\)O\({}_{40}\)\({}^{3-}\) in the catalyst and hydrogen peroxide forms {PO\({}_{4}\)[WO(O\({}_{2}\))\({}_{2}\)]\({}_{4}\)}\({}^{3-}\) species that are active in oxidation reactions [19,20]. Also, the catalyst was efficient in a great variety of pure and mixed solvents due to the polar groups of the ionic liquid, providing a range of triphasic systems that allow better catalyst recovery and benzaldehyde separation. MCM-41 (mobile composition of matter) is one of the most studied mesoporous silica-based molecular sieves [21]. These materials have desirable properties for heterogeneous catalysis due to: (i) Long-range ordering of cylindrical mesopores in an hexagonal array; (ii) specific surface areas higher than 700 m\({}^{2}\) g\({}^{-1}\); (iii) tunable pore volumes between 0.7 and 1.2 cm\({}^{3}\) g\({}^{-1}\); and (iv) pore diameter between 2.5 and 4.5 nm. Such properties allow a high dispersion of catalytic species, a better accessibility to these active sites, and increase the mass diffusion of reactants than those observed for microporous materials [22]. This singular structure is possible because the synthesis procedure employs long-chain alkyl-ammonium surfactants that arrange themselves in rod-like micelles in water [23]. Such supramolecular arrangements act as structural directing agents and define the manner that silicate oligomers will interact with the cationic head group before crystallizing in the final material [24]. Therefore, disturbances in this molecular assembly might lead to microstructural changes in MCM-41 solids, affecting their final properties as well [25; 26].