Font Size: a A A

Study On Iron Catalyst For Mesoporous Carbon Graphitization And Magnetic Functionalization

Posted on:2012-04-07Degree:MasterType:Thesis
Country:ChinaCandidate:W J GaoFull Text:PDF
GTID:2131330335980612Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
Ordered mesoporous carbon nanomaterials have received much attention during recent years due to their surface chemical inertness, thermal stability, tunable uniform pore size, large surface areas and pore volume. They are used extensively as the new energy storage materials, catalysts, adsorbents, and other aspects of biomedical. In this paper, we used mesoporous carbon as the research object, and functional it's graphitic and magnetic properties. In the experiment, using three block copolymer PEO-PPO-PEO as a template, multiconstituent co-assembly method, synthesized partically graphitic and magnetic mesoporous carbon, separately used as double-layer capacitor energy storage materials and catalyst. In the electrochemical and catalytic performance test, respectively, showed a superior capacitive behavior and catalytic activity.Paper is divided into three chapters, the first chapter is a detailed review, introduced the mesoporous carbon, graphitic carbon and magnetic carbon materials development and research status.Chapter 2 described synthesis of the partically graphitic ordered mesoporous carbon. Pluronic F127 is used as a structure-directing agent, the low-polymerized phenolic resol as a carbon source, ferric oxide as a catalyst and silica as an additive. The inorganic oxides can be successively completely eliminated from carbon. Small-angle XRD, and N2 sorption analysis show that the resultant carbon materials upon low-temperature pyrolysis (900°C) possess the ordered 2-D hexagonal mesostructure, uniform bimodal mesopores (about 1.5 and 6.4 nm), high surface areas (~ 1300 m~2/g), and large pore volumes (~ 1.50 cm~3/g). Wide-angle XRD patterns demonstrate that the presence of ferric oxide catalyst and silica additive leads to a marked enhancement of graphitic ordering in the frameworks of ordered mesoporous carbons. Raman spectra provide evidences on the increased content of graphitic sp~2 carbon structures. TEM images confirm that the ordered mesostructures with numerous domains are composed of characteristic graphitic carbon nanostructures. The evolution of the graphitic structure is dependent on the temperature and the concentrations of the silica additive, and ferric oxide catalyst. Once the metallic oxides are reduced, the metal nanoparticles sinter together. Simultaneously, the immobilization of the metal may be impoved during in situ high-temperature reduction by organic species and carbon. Large particles are phased-separated from the carbon matrix. Consequently, the graphitic degree of the carbon mesostructured framework may be decreased to some extent. Electrochemical measurements performed on this graphitic mesoporous carbon when used as an electrode material for an electrochemical double layer capacitor shows rectangular-shaped cyclic voltammetry curves over a wide range of scan rates, even up to 200 mV/s, with a large capacitance of 155 F/g in KOH electrolyte. The method can be widely applied to the synthesis of graphitized carbon nanostructures.In Chapter 3, synthesis and application of Fe-based magnetic mesoporous carbon catalyst. The obtained materials have ordered 2-D hexagonal mesostructure, high high surface areas (~ 360 m~2/g), and large pore volumes (0.41 cm~3/g). When dissolved silica, the surface areas became more larger (~ 1800 m~2/g and 1.70 cm~3/g). By changing the iron content of the material to adjust the magnetic material(Ms=1.6, 5.9, 7.6 emu/g), and used as catalyst in the reaction of hydrogen peroxide oxidation of phenol. Discussing catalystic activities and selectivity in phenol hydroxylation by H2O2 over various reaction time, reaction temperature, amount of catalyst and hydrogen peroxide. This material in the hydrogen peroxide oxidation of phenol in the reaction system, showing high catalytic activity, the reaction can be in a very short period of time to achieve balance, almost no by-products.
Keywords/Search Tags:graphitic carbon, magnetic catalyst, mesoporous carbon, phenol hydroxylation
PDF Full Text Request
Related items