Ionic liquid based CO2 capturing cell for greenhouse gas reduction

Abstract

Room-temperature ionic liquids are utilized in a new CO2 capturing fuel cell. The cell is aimed at the efficient removal of atmospheric CO2 as the first step of a Carbon Capture and Storage (CCS) system. Efficiently extracting CO2 directly from the atmosphere eliminates the need for point source capture and is the only viable method for sequestering CO2 generated by the transportation sector. In this work the optimized operating conditions and efficiency improvements of an ionic liquid based CO2 capturing cell will be reported. The experimental cell is similar in construction and operation to a hydrogen fuel cell – a thin supported liquid membrane is placed in intimate contact with two conducting electrodes and gas diffusion layers with Pt catalysts at the interfaces where CO2 electrochemical assisted capture and release reaction takes place. CO2 is converted to soluble carbonates at the cathode which is maintained at high pH and is subsequently liberated at low pH at the anode. The use of ionic liquids with low viscosity, intrinsically negligible vapor pressure, good water miscibility and high electrochemical stability in basic conditions (such as 1-Butyl-1-methylpyrrolidinium dicyanamide) is highly advantageous in improving the efficiency of the CO2 capture membrane while simultaneously making it more robust. The ionic liquid based approach is compared to alternate membrane based electrochemical approaches as well as existing aqueous electrochemical CO2 concentration.