Low pressure glow-discharge methanation with an ancillary oxygen ion conductor

Plasma technology is gaining increased interest for the reduction of carbon dioxide (CO2) to carbon monoxide (CO) and oxygen (O2). CO is a reaction partner with hydrogen (H2) to produce gas and fuel. This paper elaborates an improved method to produce methane (CH4) by plasma induced dissociation of carbon dioxide and H2 in one single setup. A low pressure glow discharge plasma with an integrated zirconia based ion conductor transports oxygen ions (O2−) in or out of the reaction chamber. Transporting oxygen ions into the reaction chamber is a way to have a controlled amount of water vapor for the conducted experiments. In contrast, leads the reduced amount of O2 ions to a theoretical decrease in the recombination of CO and O2 to CO2 in the ionized gas and therefore increases the CO2 conversion rate. The applied voltage to the ion conductor for the outward ion transportation and the power of the plasma source current have a major impact on the amount of extracted O2− ions. The effect of these parameters on the CO production rate and the formation of methane are investigated. A positive effect of the plasma current on the amount of CO and CH4 is detected. The influence of the temperature increase from the heated ion conductor relates to an undesired increase of the recombination rate of CO and O2 to CO2, but has a positive effect on the methanation.