Magnetic core-shell-structured Fe3O4@CeO2 as an efficient catalyst for catalytic wet peroxide oxidation of benzoic acid.

Abstract

A magnetic core–shell-structured Fe3O4@CeO2 catalyst was prepared by a simple solvothermal method and applied in the solid state for catalytic wet peroxide oxidation (CWPO) of benzoic acid. The obtained catalyst was characterized by N2 adsorption–desorption, X-ray diffraction (XRD), magnetic measurements, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that Fe3O4@CeO2 possessed superior catalytic efficiency for CWPO of benzoic acid than that of Fe3O4. The high catalytic activity was caused by a synergistic effect between Fe3O4 and CeO2, which assisted the decomposition of H2O2 into hydroxyl radicals (·OH). Fe3O4@CeO2 exhibited low Fe leaching of 4.2 mg L−1, which approximately accounted for barely 0.76% of the total Fe amount in the catalyst. The effects of radical scavengers indicated that benzoic acid was degraded mainly by ·OH attack, which occurred both in the bulk solution and on the Fe3O4@CeO2 surface. In the stability tests, there was loss of merely 4% in the benzoic acid removal rate after six cycles of reaction, and the saturation magnetization of Fe3O4@CeO2 hardly changed, which suggested that the Fe3O4@CeO2 catalyst was fairly effective in reutilization and stability.