Comparison between Cu(II) schiff base complex immobilized on SBA-15, Fe304 and Fe3O4/mesoporous silica catalysts for alcohols oxidation

In this study, Cu(II) Schiff base complex was synthesized and immobilized on a silica layer and magnetic core that was prepared through inverse microemulsion and precipitation method respectively. Structural and magnetic properties of the catalyst were characterized using XRD, TEM, FT-IR and VSM methods. XRD pattern of Fe3O4 nanoparticles showed a pure cubic phase. TEM image of nanoparticles confirmed spherical morphology containing magnetic core about 20 nm and silica layer around 50 nm thicknesses. VSM curve of Fe304 nanoparticles showed superparamagnetic property. Fe304@nSiO2@mSiO2@Cu(II) Schiff base catalyst was synthesized and their structural properties were characterized with TEM and IR methods. TEM image of the nanoparticles confirmed the presence of a magnetic core with diameter of 300 nm, amorphous silica layer – 15 nm and mesoporous silica layer - 70 nm. These catalysts were compared with SBA-15-Cu(II) Schiff base for alcohols oxidation. Interestingly, Fe304@ SiO2@Cu(II) Schiff base had the highest catalytic performance for oxidation of benzyl alcohol in the presence of hydrogen peroxide in water at 80°C and in contrast, SBA-15@Cu(II) Schiff base had the highest catalytic activity for benzyl alcohol oxidation in the presence of tert-Butyl hydroperoxide and acetonitrile as solvent at 60 °C.