Copper electrowinning-coupled CO2 capture in solvent based post-combustion capture

With continuous price drop of the renewable electricity, electrochemical CO2 capture approaches are gaining increasing attention owing to their advantages of low temperature operation, high energy efficiency and flexible plug-and-play operation mode. However, the existing electrochemical approaches are either energy-intensive or inefficient with impractically low current densities. Herein, we report an electrowinning-coupled CO2 capture (ECC) system which integrates commercially-applied hydrometallurgical technique of electrowinning with solvent-based CO2 absorption for an energy-efficient CO2 capture. Using copper as the electrochemical medium and ammonia as the CO2 capture sorbent, the ECC system receives comprehensive investigations including thermodynamic modelling, linear sweep voltammetry measurement, microkinetic modelling, CO2 desorption performance measurement and full ECC cell operation. We experimentally achieve a low energy requirement of 52 kJe/mol CO2 at anodic and cathodic current densities of 470 A/m2 and 2500 A/m2, respectively. This energy performance is very competitive with the state-of-the-art electrochemical CO2 capture systems that usually require electrical energy of > 100 kJe/mol CO2 at current density of > 50 A/m2. The experimentally-obtained results indicate that the ECC system using inexpensive copper electrodes and ammonia-based electrolytes can offer a practical approach for energy-efficient CO2 capture.