Synthesis of Porous Fe3C Based Composite Beads as Heterogeneous Catalytic Oxidations.

A series of multi-scaled cementite/iron porous carbon (CIPC-T) composites with extremely low nitrogen content and millimeter-size spherical format are successfully prepared through a simple carbothermal pyrolysis of exchanged resin spheres by ferric oxalate anions. CIPC-T samples are characterized to be composted of highly dispersed core-shell structured Fe3C/Fe @ graphitic carbon (CI@GC) nano-particles embedded in porous amorphous carbon frame. The mechanism for the formation of the composites is proposed based on the results of XRD, SEM, TEM and TGA. Interestingly, Fe3C contents can be easily controlled just by different carbothermal temperatures. The CIPC-T samples prove to be active to catalyze oxidation of ethylbenzene to acetophenone and Fenton-like oxidation of methylene blue as a heterogeneous catalyst. For the first time, the role of Fe3C for the catalytic oxidation has been confirmed. Either the spherical format of the composites or the magnetization property facilitates the separation of the catalyst from the reaction solution. More importantly, no leaching of iron active sites occurs during the reactions and the catalyst can be reusable in continuous runs without obvious loss of activity. Such high stability of iron sites in the composites is ascribed to the protection of the outer graphitic carbon shell of CI@GC.