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

A magnetic core-shell-structured FeO@CeO 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 N adsorption-desorption, X-ray diffraction (XRD), magnetic measurements, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that FeO@CeO possessed superior catalytic efficiency for CWPO of benzoic acid than that of FeO. The high catalytic activity was caused by a synergistic effect between FeO and CeO, which assisted the decomposition of HO into hydroxyl radicals (·OH). FeO@CeO exhibited low Fe leaching of 4.2 mg L, 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 FeO@CeO 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 FeO@CeO hardly changed, which suggested that the FeO@CeO catalyst was fairly effective in reutilization and stability.