Dissociation of Carbon Dioxide Using a Microdischarge Plasma Reactor

This paper reports an experimental study on dissociation of carbon dioxide using a microdischarge plasma reactor at ambient conditions. Carbon dioxide contributes to more than 80% of the greenhouse gas emissions in United States. The microdischarge plasmas can be a very promising method in dissociating gases, including carbon dioxide, due to their lack of need for catalysts, operating at temperatures lower than conventional thermochemical dissociation processes and ease of operation. A microhollow cathode discharge plasma reactor was designed and prototyped for CO₂ dissociation. The reactor included metal electrodes that were attached to both sides of a dielectric material with a micro-size through hole. The electrodes and the dielectric material were placed perpendicular to flow direction for dissociation to occur as carbon dioxide passed through the hole. A set of experiments were conducted to investigate the effect of flow rate and applied voltage on the composition of the products, energy conversion efficiency and CO₂-to-CO conversion yield of the microdischarge plasma reactor. Temperature of reactants and products were continuously measured; applied voltage was set using a high-voltage power supply; and molar composition of products for each case was analyzed using gas chromatography. Results showed that CO₂ dissociation rate, energy conversion efficiency and CO₂-to-CO conversion yield increased with applied voltage. Moreover, CO₂ dissociation rate and conversion yield decreased while energy conversion efficiency increased with increasing flow rate.