Confined Pt and CoFe2O4 Nanoparticles in a Mesoporous Core/Shell Silica Microsphere and Their Catalytic Activity

Confined Pt and CoFe2O4 nanoparticles (NPs) in a mesoporous core/shell silica microsphere, Pt-CoFe2O4@meso-SiO2, were prepared using a bi-functional linker molecule. A large number of Pt NPs in Pt-CoFe2O4@meso-SiO2, ranging from 5 to 8 nm, are embedded into the shell and some of them are in close contact with CoFe2O4 NPs. The hydrogenation of cyclohexene over the Pt-CoFe2O4@meso-SiO2 microsphere at 25 degrees C and 1 atm of H, yields cyclohexane as a major product. In addition, it gives oxygenated products. Control experiments with O-18-labelled water and acetone suggest that surface-bound oxygen atoms in CoFe2O4 are associated with the formation of the oxygenated products. This oxidation reaction is operative only if CoFe2O4 and Pt NPs are in close contact. The Pt-CoFe2O4@meso-SiO2 catalyst is separated simply by a magnet, which can be re-used without affecting the catalytic efficiency.