Stability improvement of the advanced electrochemical CO₂ capture process with high-capacity polyamine solvents

The electrochemically mediated amine regeneration (EMAR) technology is regarded as a promising electrochemical carbon capture method which has the potential to be cost-effective, environmentally friendly and energy efficient. Extensive research has been conducted on the EMAR process, ranging from the mechanism to technical and economic evaluations. However, the practical application of this technology still encounters certain challenges, including limited absorbent options, unclear reaction mechanism, poor copper cycling performance and equipment corrosion hazards. To solve these problems, ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA) are selected as potential absorbents for the EMAR process in this work. The different Cu-polyamine systems receive comprehensive investigations including electrochemical characterization, analysis of cathodic nucleation mechanism, corrosion assessment, and absorption/desorption performance evaluation. We experimentally reveal the electrodeposition mechanism of copper ion and predict the quality of copper deposited layers in different polyamine solutions. In addition, the results show that the adsorption of copper-amine ionic complexes on the surface of carbon steel in the EMAR system will enhance the corrosion resistance. Based on the Cu-DETA system, we achieved a low energy consumption of 36.67 kJ_e/mol CO₂ at a current density of 0.01 A/cm², which is very competitive with the state-of-the-art EMAR systems.