High-Efficiency Carbon Dioxide Reduction Using Nonthermal Plasma Desorption

We present a highly efficient carbon dioxide (CO₂) reduction treatment technique using an adsorbent and nonthermal plasma flow at the laboratory scale. The plasma reactor consists of twelve surface discharge elements, which are energized by a 10-kHz bipolar pulsed high-voltage power supply. As an adsorbent, the molecular sieve zeolite 13X is used, and it is placed downstream of the plasma reactor. In the physical adsorption process, approximately 10% CO₂ gas with flow rate 10 L/min is prepared by 99.5% CO₂/N₂ cylinder and a nitrogen cylinder. It is then introduced into the flow channel, and CO₂ is adsorbed by the adsorbent. After the adsorption process, the circulation flow channel is set and the N₂ plasma flow is generated with a blower. Consequently, CO₂ adsorbed by the adsorbent is desorbed with higher concentration (currently ~20%) and reduced to CO with high efficiency. The generated CO can be reused as a fuel. We evaluate the experimental results by calculating the conversion efficiency of CO₂ to CO and the energy efficiency of the plasma. When the number of repetitions of experiments is 5, a maximum CO concentration of 5% and a maximum CO₂ concentration of 20% are reached. The energy efficiency associated with the conversion of desorbed CO₂ to CO reaches 14% with the plasma power of 300 W. Discussions are carried out by comparing the value with those obtained in other studies on the plasma reduction of CO₂.