Production of Nano-Sized Carbon Materials by Methane Decomposition using a Thermal Plasma Torch

Summary form only given. Nano-sized carbon materials are produced in different structures depending on the precursor and the processing condition used for a direct conversion of methane by thermal plasma process. For this synthesis process, a mixture of argon and hydrogen is used as a plasma forming gas for the thermal plasma jet generated by a DC non-transferred plasma torch. By introducing only pure methane into the mixture plasma flame, nano-sized carbon blacks of spherical and sheet-like shapes are produced simultaneously. On the other hand, by injecting a catalytic metal additive mixed with methane into the plasma, a number of carbon nanotubes with a long hollow structure are synthesized in the optimal operating conditions of the torch. Morphologies and crystallization degrees of the carbon blacks and the nanotubes produced under various processing conditions are evaluated by using scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. In addition to the synthesis process, a numerical analysis on the methane decomposition by the thermal plasma is carried out to understand the distinct formation mechanisms of the nano-sized carbon materials with different structures.