Highly Efficient Epoxidation of Cyclopentene Catalyzed by Magnetically Recoverable Mg–doped Cobalt Ferrites with Greatly Improved Performances

The alkaline earth metal Mg-doped CoFe₂O₄ composite ferrite samples Mg_xCo_1-xFe₂O₄ (x=0, 0.1, 0.3, 0.5, 0.7 and 1) were prepared using a sol-gel auto-combustion route. The as-prepared samples were characterized by Raman spectrometry, X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), ICP–atomic emission spectroscopy and N₂-physisorption. The catalytic activities of the samples were tested in the cyclopentene oxidation using hydrogen peroxide (30 %) as the oxidant. Compared with the pristine CoFe₂O₄ and MgFe₂O₄, the Mg−Co composite ferrites showed much enhanced catalytic performances in the oxidation of cyclopentene with cyclopentene oxide as the main product. In particular, 95.2 % of cyclopentene conversion and 96.3 % of selectivity for cyclopentene oxide were achieved when Mg_0.5Co_0.5Fe₂O₄ was used at 60 ^oC for 8 h in the oxidation reaction. The catalyst can be easily separated by applying magnetic field and exhibits great reusability.