Production of hydrogen and carbon black by methane decomposition using DC-RF hybrid thermal plasmas

Summary form only given. In this experimental work, H/sub 2/ and CB are produced from decomposition of methane (CH/sub 4/) by using DC-RF hybrid thermal plasmas. The DC-RF hybrid plasma offers a larger volume of hot core region and lower velocity of thermal plasma flow compare to DC plasma jets. Consequently, it provides a longer residence time for the reactant gas flowing along the high temperature region with relatively uniform plasma fields across the reaction chamber. In addition, an easy ignition and stable operation of the RF torch at atmospheric pressure condition are possible due to high enthalpy fluxes supplied from the combined DC plasma jet. Plasma temperatures and equilibrium compositions of CH/sub 4//Ar mixture are obtained using thermodynamic data and by Gibbs free energy minimization method, respectively. The temperature and velocity distributions inside the reactor are also computed to get reactor design data and examine the heat balance over the reaction chamber. Lastly, one-dimensional gas phase kinetic simulations on the methane decomposition process are performed to estimate major species and their mole fraction by considering detailed reaction mechanism. The injected methane is converted mostly into H/sub 2/ with a small volume fraction of C/sub 2/H/sub 2/, and the fine carbon particles of 50-200 nm are identified from their TEM images.