Abstract:

Single-walled carbon nanotubes (SWCNTs) are prepared in large scale from Taixi anthracite coal using arc discharge technique.The properties of the arc plasma during the arcing process are analyzed in situ using optical emission spectroscopy (OES) and are correlated to the yield of SWCNTs to understand the growth mechanism of SWCNTs.The SWCNTs are characterized by TEM，TGA，Raman spectroscopy and N₂ adsorption technique.The results show that Taixi anthracite is a suitable carbon source for mass production of SWCNTs with Y₂O₃ and Ni as catalysts at a helium pressure of 0.05 MPa.The yield of SWCNTs increases as the carbonization temperature of coal-based anode increases.In the SWCNTs，there are metals and minerals that account for about 40%(mass).The coal-based SWCNTs have a diameter of 1.5—2.4 nm and a surface area of 199 m²·g^-1.The OES analysis reveals that active species such as C₂ dimers and CN species are present in the arcing plasma and the active intermediates involved in the formation and growth of SWCNTs.

Key words:

单壁碳纳米管, 煤, 电弧放电, 发射光谱

摘要：

以太西无烟煤为碳源，研究了用直流电弧放电法大批量制备单壁碳纳米管的工艺条件，考察了放电气氛及压力、催化剂种类及其用量和煤基炭棒的炭化终温对单壁碳纳米管产率的影响，采用发射光谱技术对电弧等离子体进行了实时监测，用透射电子显微镜、拉曼光谱技术、热重技术和物理吸附技术等对单壁碳纳米管产品进行了分析表征。研究表明，以稀土氧化物Y₂O₃和过渡金属Ni为催化剂、煤基炭棒为阳极，在0.05 MPa氦气下电弧放电，可实现单壁碳纳米管的批量制备，单壁碳纳米管的产量随着煤基炭棒炭化终温的升高而增大。电弧放电得到的煤基单壁纳米碳管以管束形式存在;单壁碳纳米管粗产品中金属催化剂含量低于40%（质量）;所得到的煤基单壁碳纳米管的直径在1.5～2.4 nm之间，比表面积为199 m²·g^-1，孔容为0.388 cm³·g^-1，其中中孔占60%。光谱分析表明，电弧等离子体中存在大量的C₂和一定的CN活性物种。

关键词:

单壁碳纳米管, 煤, 电弧放电, 发射光谱