A novel hydrofobic niobium oxyhydroxide as catalyst: Selective cyclohexene oxidation to epoxide

A surface modified niobium oxyhydroxide catalyst was utilized for the selective liquid-phase oxidation of cyclohexene to epoxide in the presence of hydrogen peroxide. After surface modification with a surfactant (cetiltrimetilamonium bromide -CTAB), the very active niobium oxyhydroxide (NbO2OH), presented hydrophobic characteristics and good activity for the oxidation of cyclohexene over the heterogeneous catalyst. Furthermore, the hydrophobic material presented a high selectivity toward the formation of the epoxide species. The mass spectrometry analysis of the reaction showed that epoxide species was produced with a selectivity of 60% using 0.2 mL of hydrogen peroxide, with 65% of conversion. The results strongly suggest that the reaction involves oxidizing species generated after the reaction with H2O2. The surfactant anchored over the niobium catalyst promotes a better interaction with the nonpolar substrate.

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► It was produced a modified niobia with high catalytic capacity for cyclohexene oxidation using hydrogen peroxide.
► Niobium oxyhydroxide has been modified and studied as a heterogeneous catalyst for cyclohexene epoxidation.
► The material was treated with hydrogen peroxide to generate oxidizing groups (peroxo species) on the surface.