Kinetic Drawbacks of Combining Electrochemical CO₂ Sorbent Reactivation with CO₂ Absorption

Electrochemical CO₂ capture approaches, where electrochemical reactions control the sorbent’s CO₂ affinity to drive subsequent CO₂ absorption/desorption, have gained substantial attention due to their low energy demands compared to temperature-swing approaches. Typically, the process uses separate electrochemical and mass-transfer steps, producing a 4-stage (cathodic/anodic, absorption/desorption) process, but recent work proposed that these energy demands can be further reduced by combining the electrochemical and CO₂ mass-transfer reactor units. Here, we used computational models to examine the practical benefit of combining electrochemical sorbent reactivation with CO₂ absorption due to this combination’s implicit assumptions about the process rate and therefore, the reactor size and cost. Comparing the minimum energy demand and process time of this combined reactor to those of the separated configuration, we found that the combined absorber can reduce the energy demand by up to 67% but doing so can also increase the process time by several orders of magnitude. In contrast, optimizing the solution chemistry could benefit both the energy demand and process time simultaneously.