Efficient catalytic wet oxidation of phenol using iron acetylacetonate complexes anchored on carbon nanofibres

Iron acetylacetonate complexes anchored on oxidized carbon nanofibres (CNFs) were prepared by a three steps procedure: (i) oxidation of commercial CNFs by treatment with HNO3, (ii) synthesis of acetylacetonate (acac) functional groups on the oxidized CNFs surfaces (acac/CNFs) and (iii) iron ions complexation on the acac sites of the CNFs (Fe-acac/CNFs). The surface groups exposed on the functionalized CNFs were characterized by using attenuated total reflectance Fourier transform infrared spectroscopy, temperature programmed desorption, thermogravimetric analysis and X-ray photoelectron spectroscopy. The functionalized CNFs and the iron complexes anchored on the CNFs were tested as heterogeneous catalysts for the wet oxidation of phenol with pure oxygen. Complete phenol conversion and high mineralization values were achieved with fresh and reused Fe-acac/CNFs catalysts, which demonstrate the improved stability of the catalysts under the phenol degradation reaction conditions. Furthermore these conditions are comparatively mild, typically 413 K of reaction temperature and 2.0 MPa of oxygen pressure.