Synthesis of Magnetic Mn2O3/CuFe2O4 Catalysts for the Aerobic Oxidation Synthesis of p-Hydroxybenzaldehyde

Magnetic Mn 2 O 3 /CuFe 2 O 4 catalysts for the synthesis of p -hydroxybenzaldehyde were prepared by a facile in-situ growth method at different annealing temperatures in order to study the influences of annealing temperatures on their structure, atomic composition, morphology, surface functional groups, magnetic and catalytic properties. The catalytic performance was evaluated via the aerobic oxidation of p -hydroxybenzyl alcohol to p -hydroxybenzaldehyde. All Mn 2 O 3 /CuFe 2 O 4 catalysts exhibited the activity for the synthesis of p -hydroxybenzaldehyde with the selectivity of 100% and ferromagnetic properties, which allows them to be easily separated from the solution by a magnet. When the annealing temperature increased from 300 to 500 °C, the atomic manganese content on the surface and the particle size were not modified, but highly crystalline α-Mn 2 O 3 was formed on the surface of CuFe 2 O 4 nanoparticles, leading to the enhanced conversion of p -hydroxybenzyl alcohol. It was also observed that the elemental composition and the core–shell structure of this catalyst remained unchanged after the synthesis of p -hydroxybenzaldehyde, which ensures its magnetic separation. However, when the annealing temperature rose up to 700 °C, the catalytic activity was reduced, due to the increase of Mn–O bonding strength and the growth of particles. Graphical Abstract