Evaluation of Absorbent Solutions for the Integrated CO ₂ Desorption and Electrolysis

Abstract CO 2 electrolysis is an approach that contributes to mitigating global warming. Integrated CO 2 electrolysis is a possibility to reduce operating costs by combining desorption and electrolysis. In this approach, it is important to provide sufficient CO 2 directly from the absorbent solution to the catalyst, whereby the physically absorbed CO 2 appears to play a central role. Therefore, the absorbent solution used for integrated electrolysis must meet a wide range of requirements, as it needs to supply sufficient CO 2 while being compatible with the process conditions in the cell. In this study, it is demonstrated that KOH and piperazine (PZ) are suitable absorbent solutions for integrated CO 2 electrolysis among the three tested groups of absorbents – namely, inorganic, amines, and physical absorbents. The results reveal that physical absorbents provide the highest amount of accessible CO 2 for electrolysis, whereas inorganic absorbents exhibit the highest compatibility with the membranes. KOH and PZ demonstrate the ability to withstand the electrochemical conditions during CO 2 electrolysis and the capability to produce C 2+ products during integrated CO 2 electrolysis. These results highlight the critical importance of absorbent selection and demonstrate the feasibility of using KOH as well as amine‐based solutions, such as PZ, for integrated CO 2 electrolysis.