Hydrogasification of carbon in an atmospheric pressure microwave plasma

Hydrogasification of carbon (C + 2H(2) -> CH4) was studied using a microwave plasma in atmospheric pressure Ar/H-2 mixtures. When the activated Ar/H-2 gas stream interacted with cold carbon particles downstream of the microwave cavity, CH4 (methane) was the only stable gasification product, as measured by gas chromatography. However, when carbon particles were injected into the plasma within the microwave cavity, both C2H2 (acetylene) and C2H4 (ethylene) were measured in addition to CH4. To identify a gasification mechanism by the microwave plasma, UV emission and minimum operational power required to maintain plasma were measured. From the experimental results, the initial reaction step leading to CH4 is thought to be a chemisorption-desorption reaction of hydrogen radical onto a carbon particle. For the C2H2 and C2H4 generation, hydrogen ion reaction with a carbon particle is suggested.