QQ客服 官方微博 反馈留言

题名	多壁碳纳米管的制备及其生长机理研究
作者	崔彦斌
学位类别	博士
答辩日期	2008-06-12
授予单位	中国科学院过程工程研究所
授予地点	过程工程研究所
导师	陈运法
关键词	多壁碳纳米管 制备 生长机理
其他题名	Synthesis and Growth Mechanism of Multi-Walled Carbon Nanotubes
学位专业	化学工程
中文摘要	碳纳米管具有优良的物理和化学性质，因此在许多领域具有潜在的应用前景。碳纳米管的高效、优质合成是碳纳米管应用的基础。对于碳纳米管的制备，关键是选择合适的催化剂和碳源化合物。碳纳米管的生长机理对于碳纳米管的可控制备至关重要。本论文对化学气相沉积法制备碳纳米管中的关键问题（催化剂和碳源化合物的选择）进行了探索，同时采用热重-质谱(TA-MS)联用技术对碳纳米管的生长机理进行了研究。主要研究内容和结论如下： (1) 以环己烷为碳源化合物，Fe-Co/γ-Al2O3为催化剂，得到了纯度较高，石墨化程度较好，准定向生长的多壁碳纳米管。积碳量可达到460%，表明环己烷是一种较理想的碳源化合物。得到的最优反应条件为：反应温度为590℃，反应时间为60min，载气流量为50ml/min，催化剂负载量为3mmol/g，优化的催化剂中Fe和Co的摩尔比为1：1。 (2) 以乙烯为碳源化合物，Fe-Mo/MgO为催化剂，得到了纯度较高，石墨化程度较好的多壁碳纳米管，积碳量可达到1250%。得到的最优反应条件为：反应温度为700℃，C2H4流量为20ml/min（N2流量为100ml/min），反应时间为60min。 (3) 以Ni-Mo/MgO为催化剂，得到了甲烷制备碳纳米管的优化反应条件：反应温度为900℃，反应时间为60min，CH4和H2流量分别为100ml/min和20ml/min （即流量比CH4:H2 = 5:1）。热重结果表明在催化剂的作用下，甲烷在860℃开始生长碳纳米管。质谱结果表明在生长碳纳米管的过程中反应体系仅有H2和C2物种生成，通过相关实验分析证明了Ni-Mo/MgO催化剂裂解甲烷制备碳纳米管的生长过程遵循C2机理。同时，依据C2H4和C2H2离子流强度的不同变化趋势，提出了C2H2和C2H4分别作用于碳纳米管的成核和生长阶段的新观点。 (4) 制备得到了新型三组分金属催化剂(Fe-Ni-Mo/MgO)，拓宽了制备碳纳米管的催化剂体系。实验结果表明，该催化剂具有良好的催化活性和较长的催化寿命，所得到的碳纳米管纯度较高，最高产量可达到71倍左右。热重结果表明在Fe-Ni-Mo/MgO催化剂的作用下，甲烷在830℃左右就可生长碳纳米管。从结果发现，在不同的催化剂作用下(Ni-Mo/MgO 和Fe-Ni-Mo/MgO)，甲烷制备碳纳米管的生长机理均遵循C2机理。
英文摘要	For their outstanding chemical and physical properties, carbon nanotubes (CNTs) have shown promise of a wide range of applications. Large scale synthesis of high quality CNTs is the basis of their applications. It is predominant to select a proper catalyst and carbon precursor for the preparation of CNTs. The growth mechanism of CNTs is very important for the controllable preparation of CNTs. In this dissertation, we will concentrate on the studies of the catalyst and carbon source’s selection of the synthesis of CNTs by chemical vapor decomposition (CVD) method. Meanwhile, we investigate the growth mechanism of CNTs by thermal analysis-mass spectroscopic (TA-MS) technique. The main contents of this dissertation are summarized as follows: (1) High-quality quasi-aligned multi-walled carbon nanotubes (MWNTs) have been produced by catalytic decomposition of cyclohexane over Fe-Co/γ-Al2O3 catalyst. An over 460% yield of MWNTs is obtained and the MWNTs are well graphitized. The results demonstrate that cyclohexane is an ideal carbon source for the synthesis of CNTs. The optimal conditions are following: reaction time of 60min, reaction temperature of 590℃, flow rate of carrying gas about 50 ml/min, catalyst loading of 3mmol/g, the molar ratio of Fe and Co around 1:1. (2) High-quality MWNTs have been produced by catalytic decomposition of ethylene over Fe-Mo/MgO catalyst. An over 1250% yield of MWNTs is obtained and the MWNTs are well graphitized. The optimal reaction conditions are following: reaction time of 60min, reaction temperature of 700℃, flow rate of C2H4 about 20ml/min and flow rate of N2 about 100ml/min. (3) The optimal reaction conditions of MWNTs synthesized by the decomposition of methane over Ni-Mo/MgO catalyst are preferred following: reaction time of 60min, reaction temperature of 900℃ and flow rate ratio of CH4 to H2 about 100:20. The results of thermogravimetry (TG) indicate that MWNTs begin to growth around 860℃. The results of MS show that only H2 and C2 species generate along with CNTs growth. The relevant results prove that methane follows C2 growth mechanism. At the same time, an opinion that C2H2 and C2H4 species played different roles in nucleation stage and growth stage of CNTs growth, respectively, was put forward. (4) A new tri-metallic catalyst (Fe-Ni-Mo/MgO) is obtained, which is helpful to look for new catalyst system in the preparation of CNTs by CVD method. The experimental results indicate that the catalyst has good catalytic activity and the purity of the products is high. The maximum carbon yield can reach to 71 times of the catalyst. The results of TG indicate that MWNTs begin to growth around 830℃. The experiment results indicate that methane follows C2 growth mechanism with different catalysts (Ni-Mo/MgO and Fe-Ni-Mo/MgO).
语种	中文
公开日期	2013-09-13
页码	129
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1190]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	崔彦斌. 多壁碳纳米管的制备及其生长机理研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2008.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。