Preparation And Catalytic Properties Of Porous Composite Of Carbon Containing Iron

Transition-metal carbide is a kind of material which not only has high meltingpoint，hardness，thermal stability and mechanical stability，but also resists almost allkinds of chemical corrosion at room temperature[1,2]. In traditional synthesis methods，transition-metal carbide[3,4]are prepared via carbonizing the metal oxide or its hydrateor metal powder as precursor and carbon powder at high temperature. Because of thehigh temperature sintering and excess carbon powder，the surface of metal carbides issometimes covered by a thick carbon layer，which possibly hinders their applications.As a kind of new catalytic materials，transition metal carbides have receivedwidespread attention because of its good hydrothermal stability，multilevel porestructure and relatively larger specific surface area. Among numerous metals，iron isvery interesting in the research due to its high activity for most substrates inheterogeneous oxidations and to its low cost. In the project，porous carbon containingmetal carbide and iron composite was selected to be used for the phenol hydroxylationreaction as catalyst. At present most iron series catalysts are in powder form，therefore，the process of catalytic recycling must go through tedious centrifugal separation process.However，our material is in hard bead format and is magnetic，which can be recycledthrough a simple magnetic separation. The material is of great significance for industrialapplication of catalysts.In this paper，one step carbonization under high temperature was used forpreparation of mesoporous carbon containing metal carbide and iron composites. Thematerials were characterized by XRD，SEM，N2adsorption and desorption isotherms，and were used to catalyze heterogeneous oxidations.The characterization results showed that the samples synthesized with differentamounts of sources of iron and under the same temperature carbonization have the samecomposition：The samples synthesized with same amount of sources of iron and underthe different temperature carbonization have different compositions： samplessynthesized under900℃are consisted of the graphitization of carbon， iron and ironcarbide，while iron and part of the crystal planes of iron carbide and ferroferric oxide for900℃and ferroferric oxide and iron for550℃.In catalytic applications，this material can keep the bead format，and can recovered without any centrifugation or filtration. Its magnetic property is also helpful for theseparation here. For phenol hydroxylation reaction，the catalyst showed good catalyticactivity，and can be reused even after more than ten runs. In addition，the catalystproved to be also active for naphthol hydroxylation，suggesting its advantage for bulkyreactants.