High energy efficiency in syngas and hydrocarbon production from dissociation of CH4-CO2 mixture in a non-equilibrium pulsed plasma

The efficient production of syngas from a CH4 + CO2 mixture in an atmospheric pulsed glow discharge, sustained by corona pre-ionization, has been investigated. The products were mainly syngas (CO, H-2) and hydrocarbons up to C-4, with acetylene having the highest selectivity. The energy efficiency was within 15 - 40% for different experimental conditions, which demonstrates a comprehensive improvement relative to the achievements of other types of non-equilibrium plasma. These values are, however, comparable with the efficiencies obtained by gliding are plasmas but this plasma operates at near room temperature. Furthermore, it has been shown that the energy efficiency is increased by decreasing the effective residence time. The effects of molar ratio CH4 : CO2, voltage. repetition rate and gas flow rate on conversion, energy efficiencies and the selectivities have also been investigated. The higher efficiency obtained in this kind of plasma is discussed and attributed to the short pulse regime and electric field uniformity.