Production of hydrogen and nano carbon powders from direct plasmalysis of methane

In this study, a single-stage, non-catalytic, dry methane plasmalysis process for producing mainly hydrogen and carbon powders using an atmospheric-pressure microwave plasma reactor is demonstrated. A high selectivity of H2 and carbon powders (C1), and a low required energy consumption of H2 could be obtained simultaneously at a low-applied power and a high inlet concentration of CH4 ([CH4]in), reaching 86.0% (selectivity of H2), 50.7% (selectivity of C1), and 6.7 eV/molecule–H2, respectively, at 0.8 kW, [CH4]in = 20%, and 12 slpm when CH4 gas was fed from the downstream of the cavity resonator. In addition, large amounts of nano carbon powders, which consisted of C atoms and had a graphite–rhombohedral structure with a particle size of about 50 nm, were produced. These particles had potential for using as a support for platinum catalysts in fuel cells.