Electrolysis of carbon dioxide for carbon monoxide production in a tubular solid oxide electrolysis cell

Highlights: • An experimental study for the CO regeneration was demonstrated. • Higher current densities at higher temperatures were obtained. • The scale of the combined system was estimated experimentally at 800 °C. • The required surface area of the cells was estimated to be 65.6 km²/BF unit. • The combined system may contribute to establishing a low-carbon society. - Abstract: An active carbon recycling energy system (ACRES) based on carbon recycling has been proposed as a new energy transformation system. This energy transformation system reduces the carbon dioxide (CO₂) emissions in the atmosphere during the iron-making process. An experimental study for electrochemical CO production by CO₂ electrolysis based on the ACRES concept was carried out using a tubular solid oxide electrolysis cell. Experimental results show that the CO and oxygen (O₂) production rates at 800, 850, and 900 °C were almost proportional to the current passing through the cell. Both ionic conductivity and the chemical kinetics of CO₂ decomposition increased with increasing temperature. The highest current density and CO production rate at 900 °C were 2.97 mA/cm² and 0.78 μmol/(min cm²), respectively. On the basis of the electrolytic characteristics of the cell, the scale of the combined ACRES CO₂ electrolysis/iron-making system was estimated