Novel protonated Fe-containing mesoporous silica nanoparticle catalyst: excellent performance cyclohexane oxidation

Abstract

A mesoporous silica structure (MSN) was synthesized using the sol–gel method, followed by iron incorporation and protonation which afforded Fe-MSN and H/Fe-MSN with Si/Fe ratios of 20. Nitrogen physisorption confirmed their mesoporous structures with pore diameters of 3.9 nm. Iron incorporation decreased the degree of catalyst crystallinity. Fe-MSN and H/Fe-MSN catalyzed the oxidation of cyclohexane to cyclohexanone using hydrogen peroxide at 298 K in 1 h. The significant advantages of these catalysts were high conversion, short reaction time, easy work-up, and compatibility with various organic and aqueous solvents. The cyclohexanone product was obtained with excellent conversions of 86 and 97% at 298 K using Fe-MSN and H/Fe-MSN, respectively. H/Fe-MSN catalyst gave a higher conversion than Fe-MSN. A comparative study of cyclohexane oxidation in the presence of H₂O₂ over H/Fe-MSN heterogeneous catalyst showed that H/Fe-MSN had excellent activity at low temperature.