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Preparation of Tungsten Carbide Loaded on Carbon Composite and Its Electrochemistry Performance

Author: YuAiMei
Tutor: ZhengHuaJun
School: Zhejiang University of Technology
Course: Applied Chemistry
Keywords: Tungsten carbide Polyporous carbon Solution-grafting Synchronous reduction and carbonization Milling method Hydrothermal method Electroreduction of p-nitrophenol Electrooxidation of methanol
CLC: O614.613
Type: Master's thesis
Year: 2011
Downloads: 109
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Abstract

For the reason that tungsten carbide possesses the similar surface electronic structure with platinum, tungsten carbide displays a Pt-like catalytic property in some chemical and electrochemical reactions. Tungsten carbide is the promising material to take place of noble catalytic materials such as catalytic hydrogenation、dehydrogenation、isomerization and full cell and so on. However, the catalytic property of tungsten carbide is still very low compared with that of Pt. Therefore, the preparation of tungsten carbide with high catalytic property has been carried more attention at the present time. The paper has summarized the recent-development of tungsten carbide、the preparation-methods of tungsten carbide and the application of template method in material synthesis.In this subject, the composite material C/WC1-x is prepared by the method "solution grafting-high energy ball milling-synchronous reduction and carbonization", the ammonium paratungstate and sucrose as the tungsten and carbon source respectively. The catalytic property of the composite material on p-nitrophenol is measured by cyclic voltammetry, and the relationship between its structure and property is discussed. The composite material possesses mesoporous structure and the specific surface area is high, these can be the reason that it has high catalytic activity on p-nitrophenol. At last, the composite material W2C/C is prepared by ethanol as the dispersing agent, the raw material ball-milled directly and synchronous reduction and carbonization.In this subject, for the ammonium paratungstate and sucrose as the tungsten and carbon source respectively, the composite material WC/C by the method "solution grafting assisted by ethanol-synchronous reduction and carbonization in atmosphere CH4/H2", the mesoporous molecular sieves (SBA-15, MCM-41, KIT-6) as the template. The surface topography、phase structure and chemical composition of WC/C is studied by the TEM、EDX、XRD and low-temperature N2 adsorption-desorption. At the same time, the catalytic property of WC/C is measured by electrochemical means in the 50% ethanol+0.1 mol/L PNP+ saturated KCl and 0.5M H2SO4+2M CH3OH, the relationship between their structure and propertiy is discussed. Experimental results illustrate that all the tungsten carbide composite materials have good lattice structure. The WC/C materials prepared by SBA-15 and MCM-41 as template display the specific surface area of 226 cm/g and 153 cm/g and the average pore size of 4 nm. These composite materials have high catalytic activity on p-nitrophenol and methanol. Three phases (WC、WC1-x、W2C) are prepared, and their catalytic oxidation properties on methanol are discussed. The experimental results explained that catalytic activity of three phases on methanol varys considerably. The WC phase has obvious electro-oxidation activity on methanol solution.In this subject, tungsten powder hydrogen peroxide and ammonium acetate are the raw materials, the composite material tungsten carbide can be obtained by the hydrothermal template method-synchronous reduction and carbonization, and the tungsten carbide is loaded by few amount of platinum. The catalytic property of composite materials is measured in p-nitrophenol and methanol solution, respectively. The experimental results demonstrate that the Pt-WC/C has better electro-oxidation activity on methanol than that of Pt.

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