The effects of gas, pressure and temperature on the production of amorphous carbon nanotubes were investigated using an arc discharging furnace at controlled temperature. Co/Ni alloy powder was used as catalyst. The discharge current was 80 A and voltage was 32 V. The optimal parameters were obtained: 600 temperature, hydrogen gas and 500 torr pressure. The productivity and purity of amorphous carbon nanotubes are 6.5 gram per hour and 80%, respectively. The diameter of the amorphous carbon nanotubes is about 7 20 nm.

Large amounts of amorphous carbon nanotubes (ACNTs) were prepared with Co–Ni alloy powders as catalyst in hydrogen gas atmosphere by a modified arc discharging furnace which can control temperature during the electric arcing process. The experimental results indicate that the cooperative function of temperature and catalyst plays an important role in the soot production rate and the relative ACNT purity. When temperature increases from 25°C to 700°C, the soot production rate increases from around 1 g/h to 8 g/h, the best relative ACNT purity at 600°C can reach up to 99% compared to the room temperature sample. Without catalyst, only plate graphite is formed at 25°C and very few carbon nanotubes are found when temperature increases to 600°C. TEM, SEM, HRTEM and XRD analysis showed that the as-prepared carbon nanotubes are almost amorphous. The soot production rate is 8 g/h and diameter range of amorphous carbon nanotubes is about 7–20 nm, respectively. © 2005 Elsevier Ltd. All rights reserved.

Single-walled carbon nanotubes (SWCNTs) were prepared by a modified arc discharging furnace using Fe-Ni-Mg powders as catalyst at 600◦C. The effects of catalyst composition and content on the production rate and purity of SWCNTs are investigated in this paper. When the Fe-Ni-Mg catalyst composition is 2 : 1 : 2 wt% and the catalyst content is 5 wt%, the experimental results indicate that the production of SWCNTs is 12 grams per hour, and the purity and diameter of SWCNTs are 70% and 1.22~1.38 nm, respectively. The results indicate that the cooperative function of catalyst composition and content plays an important role in the production of SWCNTs. The aim of this work is to control the production process of SWCNTs efficiently.