Electrochemical Concentration of Carbon Dioxide from an Oxygen/Carbon Dioxide Containing Gas Stream

An electrochemical cell utilizing an anion exchange membrane was used to separate oxygen and to concentrate carbon dioxide from a mixed gaseous stream. Carbon dioxide concentration was achieved from a gaseous stream composed of 49.3% carbon dioxide and 50.7% oxygen. A volumetric ratio of 3.56:1 carbon dioxide to oxygen evolution was observed. Oxygen separation occurs through reversible oxygen reduction and oxygen evolution reactions. Carbon dioxide separation occurs through homogeneous reactions between gas-phase and electrochemical reaction products on one side of the membrane to form carbonate and bicarbonate ions and neutralization of those ions on the other side of the membrane by electrochemical reactions. Current densities reached a maximum of at a cell potential of 1.2 V. Although this approach is not efficient enough to utilize for capture for fossil energy applications at this time, more active electrocatalysts and thinner ion-exchange membranes could improve the efficiency in the future, and it may be suitable for other applications such as removal of from breathing air.