# Mo(VI) Complexes Immobilized on SBA-15 as an Efficient Catalyst for 1-Octene Epoxidation
###### Abstract  
SBA-15 materials were functionalized through a post-synthetic methodology with molybdenum-Schiff bases to provide catalytic activity in epoxidation reactions. Thus, glycoloxypropyl functionalities were first attached to the surface of the mesostructured silica, followed by the reaction of the immobilized oxirane groups with 2-amino propyl pyridine. This reaction allowed the obtaining of (hydroxypropyl)-2-aminomethyl pyridine ligands, directly tethered to the surface of the mesoporous silica-based SBA-15, which resulted in excellent chelating ligands to immobilize dioxo molydenum species by a reaction with MoO\({}_{2}\)(acac)\({}_{2}\). This investigation comprises a thorough characterization of the process for building the immobilized molybdenum-Schiff base complexes, as well as the use of the obtained materials in 1-octene oxidation in the presence of organic hydroperoxides. These materials displayed high intrinsic catalytic activity in the epoxidation of 1-octene with organic hydroperoxides under a wide variety of conditions, although both the reaction solvent as well as the nature of the organic hydroperoxide, exerted a dramatic influence on the catalytic activity of these heterogeneous oxidation catalysts. Thus, whereas nonpolar solvents provided good epoxide yields with high efficiency in the use of the oxidant, polar solvents depressed the catalytic activity of the supported Mo-Schiff bases. These results have been ascribed to the competition with the solvent, when polar, for binding to the metal sites, thus avoiding the formation of the hydroperoxo-metal cycle and the epoxidation of the olefin. The catalysts presented here show good reusability with low catalytic activity decay after the first reuse. e _catalysts_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Acta_Ac_Acta_Ac_Acta_Ac_Acta_Ac_Acta_Ac_Acta_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac_Ac  
supermicropore-mesopore system to facilitate the dispersion of bulky Mo species. [PERSON] et al. [8] evaluated the oxidation capabilities of \(\beta\) zeolite functionalized with molybdenum, vanadium, and titanium atoms, that were isomorphically incorporated to the zeolite framework. Their catalytic results in epoxidation of different olefins showed a clear effect of the zeolite pore size. [PERSON] et al. [9] reported the grafting of cyclopentadienyl molybdenum complexes on the surface of \(\beta\) and Y zeolites for cyclootene epoxidation, obtaining high activity and epoxide selectivity. However, the comparison with homogeneous systems suggests the reaction is probably limited because of hindrances to the reactants' diffusion when using immobilized molybdenum complexes. To summarize, different molybdenum-containing zeolites have been successfully tested in the epoxidation of several olefins, but their microporous structure frequently involves mass transfer limitations. Another promising and widely evaluated option for the immobilization of molybdenum sites has been the use of polymers as carriers. [PERSON] et al. [2], [PERSON] et al. [10], and [PERSON] et al. [11] described the synthesis and epoxidation behavior of some Mo(VI) complexes supported on polybenzimidazole and polystyrene 2-(aminomethyl)pyridine. Catalytic results indicate that stable long-lived heterogeneous catalysts can be prepared to obtain high reaction rates and epoxide selectivity for several olefins. In a similar way, [PERSON] et al. [6] reported the immobilization of molybdenum acetylacetonate on cross-linked polymer (divinyl benzene-allyl amine) DVB-AA, leading to an efficient heterogeneous catalyst for olefins epoxidation. However, from a practical point of view, the use of polymers as catalyst supports still presents some drawbacks mainly related to their low porosity and low chemical and mechanical stability (as compared to inorganic carriers).