浮游裂解法制备微纳米炭材料

发布时间：2018-08-30 12:06

【摘要】： 碳纳米管由于具有优异的电学、光学和力学性能以及在这些方面诱人的应用前景而引起了各国科学家的广泛关注。目前,能够大规模连续化的制备碳纳米管,并且精确控制碳纳米管的直径、层数乃至手性是科学家们在碳纳米管制备领域追求的目标,而选控制备碳纳米管的关键在于能够可控的合成单壁和双壁碳纳米管。尤其是双壁碳纳米管,是一种介于单壁和多壁碳纳米管之间的重要一维炭材料,可以看做是最简单的多壁碳纳米管,并且具有明显不同于单壁碳纳米管的独特性质,所以选控制备双壁碳纳米管成为微纳米炭材料制备领域研究的热点。本文使用了一个改进的变径管式反应器,采用二甲苯作为碳源,二茂铁为催化剂前驱体,硫磺为助剂,采用浮游裂解法,成功制备得到了丝状的单壁和双壁碳纳米管。并研究了反应温度、气流流量、助剂硫含量以及进液速度和反应时间等参数对产物制备的影响。实验结果表明：通过对参数的优化,可以得到较高质量的双壁碳纳米管；通过控制反应体系中助剂硫的浓度,可以有效的选控制备单壁或双壁碳纳米管。并且基于此实验结果,建立了双壁碳纳米管的生长模型,从热力学和动力学上对双壁碳纳米管的生长机制进行了探讨。在实验中发现：由两个不同管径石英管无缝连接组成的变径反应器,可以有效的调节反应器内不同位置的气流流速,从而提高碳源利用效率,促进双壁碳纳米管的生成；并根据实验结果,对产物在变径反应器内区域选择性生长的原因以及变径结构对产物生长过程的影响作了初步的探讨。这种变径结构反应器为双壁碳纳米管大规模连续化设备的研制提供了一种新的思路和方法。
[Abstract]:Carbon nanotubes (CNTs) have attracted much attention from scientists all over the world due to their excellent electrical, optical and mechanical properties and attractive applications in these fields. The key to the choice of carbon nanotubes is the controllable synthesis of single-walled and double-walled carbon nanotubes. Especially double-walled carbon nanotubes, which is an important one-dimensional carbon material between single-walled and multi-walled carbon nanotubes, can be regarded as the simplest multi-walled carbon nanotubes and is obviously different from single-walled carbon nanotubes. Because of its unique properties, the selective preparation of double-walled carbon nanotubes has become a hot topic in the field of preparation of micro-and nano-carbon materials.
Silk-like single-walled and double-walled carbon nanotubes (SWNTs) were successfully synthesized in a modified variable-diameter tube reactor using xylene as carbon source, ferrocene as catalyst precursor and sulfur as promoter by floating pyrolysis. The reaction temperature, flow rate, sulfur content of promoter, feed rate and reaction time were studied. The experimental results show that high quality double-walled carbon nanotubes can be obtained by optimizing the parameters, and single-walled or double-walled carbon nanotubes can be effectively prepared by controlling the concentration of sulfur in the reaction system. The growth mechanism of double-walled carbon nanotubes (DWCNTs) was investigated thermodynamically and dynamically. It was found that a variable-diameter reactor consisting of two different diameter quartz tubes seamlessly connected could effectively adjust the flow rate at different positions in the reactor, thereby improving the utilization efficiency of carbon sources and promoting the formation of DWCNTs. According to the experimental results, the reasons for the regioselective growth of the products in the variable-diameter reactor and the effect of the variable-diameter structure on the growth process of the products are preliminarily discussed.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB383.1

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