CO₂ Capture via Electrolytic Regeneration Coupled with Hydrogen Production Using Weakly Acidic Potassium Salt Electrolyte

Carbon capture, utilization, and storage (CCUS) stands as a critical technology for carbon mitigation in coal-fired power plants. Conventional CO2 absorbents require high energy consumption for thermal regeneration. Although electrolytic regeneration using strong-acid salts can reduce energy demand, this approach still faces challenges such as corrosion and the simultaneous evolution of CO2 and O2. To address the dual challenges of energy efficiency and corrosion resistance in CO2 capture regeneration, this study selected a weakly acidic potassium salt as the electrolyte and adopted a flow-phase electrolytic cell characterized by low operational voltage and enhanced mass transfer efficiency. A novel integrated system combining CO2 capture, electrolytic regeneration, and hydrogen production was constructed, enabling effective oxygen and CO2 separation. Systematic experiments evaluated the impacts of electrolyte concentration, current density, temperature, and circulation flow rate on system performance, with the aim of exploring optimal energy consumption conditions for this hydrogen-integrated CO2 electrolytic regeneration system. The results demonstrate that temperature elevation exerts the most pronounced effect on reducing electrolysis voltage and lowering regeneration energy consumption. In contrast, the influence of electrolyte concentration on this electrolytic regeneration system exhibits nonlinear characteristics, with the 3 M weakly acidic potassium salt solution outperforming both 1 and 5 M counterparts. Under conditions of 80 °C, a constant current density of 200 mA/cm2 applied to the 3 M weakly acidic potassium salt solution, and a circulation flow rate of 50 mL/min, the total energy consumption is approximately 4.55 kJ. During stable hydrogen production, the hydrogen purity reaches 95%. After deducting the energy value of the generated hydrogen, the system achieves a net CO2 capture energy consumption of 54.39 kJ/mol CO2. The experimental results suggest that this system may exhibit superior competitiveness compared to strong-acid salt-based electrolytic regeneration systems in coal-fired power plant decarbonization applications.