Integrated system for electrolyte recovery, product separation, and CO2 capture in CO2 reduction

Abstract

Challenges in CO₂ capture, CO₂ crossover, product separation, and electrolyte recovery hinder electrocatalytic CO₂ reduction (CO₂R). Here, we present an integrated electrochemical recovery and separation system (ERSS) with an ion separation module (ISM) between the anode and cathode of a water electrolysis system. During ERSS operation, protons from the anolyte flow through the anodic cation exchange membrane (CEM) into the ISM, acidifying the CO₂R effluent electrolyte. Cations like K⁺ in the ISM flow through the cathodic CEM into the catholyte to balance the OH⁻ ions from hydrogen evolution. ERSS recycles electrolyte-adsorbed CO₂, recovers KOH with a 94.0% K⁺ yield, and achieves an 86.2% separation efficiency for CO₂R products. The recovered KOH can capture CO₂ from air or flue gas or be utilized as a CO₂R electrolyte, closing the CO₂ capture, conversion, and utilization loop. Compared to the conventional acid-base neutralization process, ERSS saves $119.76 per ton of KOH recovered and is applicable to other aqueous alkaline electrosynthesis reactions.