本文選題：碳化鎢 + 介孔材料��； 參考：《浙江工業(yè)大學》2014年碩士論文

【摘要】：近年來,作為替代貴金屬鉑可應用于直接甲醇燃料電池的碳化鎢材料越來越引起人們的關(guān)注。由于碳化鎢具有與貴金屬鉑相似的表面電子結(jié)構(gòu),因此在一些化學和電化學反應中展現(xiàn)出奇特的類鉑催化活性。然而與金屬鉑相比,碳化鎢材料的催化性能仍然較低。因此,如何制備催化活性高的碳化鎢材料成為當前國內(nèi)外研究的熱點。本文在綜述碳化鎢材料的制備方法及電催化性能的基礎上,分別采取兩種方法來制備碳負載碳化鎢復合材料,并研究了其催化活性。 一方面,通過液相移植的方法,以乙醇為分散劑,磷鎢酸(PTA)為鎢源,介孔分子篩SBA-15和擴孔后的CMK-3型介孔碳(OMC)為模板和載體,通過調(diào)整浸漬時間,一步還原碳化得到具有大比表面積、高催化活性的碳負載碳化鎢材料。實驗結(jié)果表明,以正硅酸乙酯(TEOS)為SiO2前驅(qū)體,P123為結(jié)構(gòu)導向劑制得的介孔分子篩SBA-15具有規(guī)整有序的孔道及大的比表面積,孔徑可達到7nm,更利于鎢源PTA的進入。而經(jīng)過擴孔后的有序介孔碳材料CMK-3的孔徑也可達到7-8nm,使得碳化鎢的負載量可以盡可能的多。通過X-射線衍射(XRD)、低溫氮氣吸脫附(BET)、能量X-射線光譜(EDX)和場發(fā)射透射電子顯微鏡(TEM)等表征方法可知,復合材料具有規(guī)整的介孔結(jié)構(gòu),較大的比表面積,因而兩種材料均在酸性甲醇溶液中表現(xiàn)出了良好的催化甲醇電氧化的催化性能。 另一方面,通過離子交換法,利用陰離子交換樹脂吸附鎢酸根,通過分析樹脂材料的熱重曲線以及紅外吸收曲線,得出最佳的碳化程序,經(jīng)過一步還原碳化得到具有大的比表面積的碳負載碳化鎢WC/C復合材料。采用XRD、EDX、 TEM、 BET等表征手段對復合材料的物相結(jié)構(gòu)、化學組成、表面形貌等進行研究。結(jié)果表明WC/C材料中碳化鎢大部分以WC的形式存在,WC在碳基體上分散均勻。在中性對硝基苯酚溶液中的測試結(jié)果表明該材料對對硝基苯酚的還原有很好的催化作用,在酸性甲醇溶液中的電化學測試結(jié)果表明該材料對甲醇氧化亦具有催化性能。
[Abstract]:In recent years, tungsten carbide, which can be used as a substitute for precious metal platinum for direct methanol fuel cells, has attracted more and more attention. Because tungsten carbide has a surface electronic structure similar to that of precious metal platinum, it exhibits unique platinum-like catalytic activity in some chemical and electrochemical reactions. However, the catalytic performance of tungsten carbide is still lower than that of platinum. Therefore, how to prepare tungsten carbide materials with high catalytic activity has become a hot topic at home and abroad. Based on the review of the preparation methods and electrocatalytic properties of tungsten carbide materials, two methods were adopted to prepare carbon-supported tungsten carbide composites, and their catalytic activity was studied. On the one hand, with ethanol as dispersant, phosphotungstate as tungsten source, mesoporous molecular sieve SBA-15 and expanded CMK-3 mesoporous carbon montmorillonite as template and carrier, the impregnation time was adjusted. Carbon supported tungsten carbide materials with large specific surface area and high catalytic activity were obtained by one step reduction carbonization. The experimental results show that the mesoporous molecular sieve SBA-15 prepared by using tetraethyl orthosilicate (TEOS) as the precursor of SiO2 P123 has regular and ordered pore channels and large specific surface area, and the pore size can reach 7 nm, which is more favorable for the entry of tungsten source PTA. The pore size of ordered mesoporous carbon material CMK-3 after reaming can reach 7-8 nm, which makes the loading amount of tungsten carbide as much as possible. By means of X ray diffraction (XRD), low temperature nitrogen adsorption and desorption (BET), energy X- ray spectroscopy (EDX) and field emission transmission electron microscopy (TEM), it is found that the composite has regular mesoporous structure and large specific surface area. Therefore, both materials exhibit good catalytic performance for methanol electrooxidation in acidic methanol solution. On the other hand, the best carbonation procedure was obtained by analyzing the thermogravimetric curves and infrared absorption curves of resin materials by ion exchange method and adsorption of tungstate with anion exchange resin. Carbon supported tungsten carbide (WC/C) composites with large specific surface area were prepared by one step reduction carbonization. The phase structure, chemical composition and surface morphology of the composites were studied by means of XRDX EDX, TM, BET and so on. The results show that most of the tungsten carbide in WC/C material exists in the form of WC, and the WC is dispersed uniformly on the carbon matrix. The results in neutral p-nitrophenol solution showed that the material could catalyze the reduction of p-nitrophenol, and the electrochemical test in acid methanol solution showed that the material also had catalytic activity for methanol oxidation.
【學位授予單位】：浙江工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TQ136.13;TM911.4

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本文編號：1952621