Synthesis of nanostructured carbons by the microwave plasma cracking of methane

One of the attractive methods of producing hydrogen and high value-added carbon is plasma-reforming of hydrocarbons. Here, nanostructured carbon was produced by methane cracking in a relatively low-energy cold plasma reactor designed in-house specifically for such purpose. Carbon samples collected at different positions in the reactor show similar structural morphologies, indicating extensive structural uniformity of the carbon during processing. Surface area and microstructure of the materials were characterized by BET surface area analysis, X-ray diffraction and transmission electron microscopy (TEM). The effects of flow rate, temperature and power were evaluated for the formation of the carbon structures. The results show that the BET surface area and pore volume of the carbon materials vary from 74 to 125 m ²/g and from 0.12 to 0.20 cm ³/g, respectively. Such variations are closely associated with the magnitude of temperature drop at the sample collection position in the cold-plasma chamber before and after methane loading. The highest BET surface area of 125 m ²/g is obtained at a power of 2000 W. TEM shows that the carbon consists of spherical particles of 40.8 ± 8.7 nm in diameter and graphene sheets.