An Electrochemically Mediated Amine Regeneration Process with a Mixed Absorbent for Postcombustion CO₂ Capture

Area of Science:

• Chemical Engineering
• Electrochemistry
• Carbon Capture Technologies

Background:

• Traditional thermal amine regeneration for CO2 capture faces challenges with high energy demands.
• Ethylenediamine (EDA) is used in electrochemically mediated amine regeneration (EMAR) but has a high vapor pressure.
• Alternative amine formulations are needed to improve EMAR process efficiency and stability.

Purpose of the Study:

• To investigate a mixed amine system of EDA and aminoethylethanolamine (AEEA) for EMAR applications.
• To evaluate the performance and properties of the mixed amine system compared to pure EDA.
• To assess the potential of the mixed amine system for stable and efficient CO2 capture.

Main Methods:

• Characterization of mixed amine systems (EDA/AEEA) for absorption rates, pH, conductivity, and CO2 capacity.
• Evaluation of electrochemical performance: cell voltage, gas desorption rate, electron utilization, and energetics.
• Long-term continuous EMAR process testing (100+ hours) with the mixed amine system.
• Analysis of desorbed gas composition and amine stability using titration and NMR spectroscopy.

Main Results:

• The mixed amine system exhibited similar properties to pure EDA, requiring no significant process modifications.
• A 50/50 EDA/AEEA mixture showed approximately 10% lower energetics compared to pure EDA.
• Continuous EMAR operation demonstrated stable cell voltage and consistent CO2 output.
• Analysis confirmed 100% CO2 desorption and no amine degradation or evaporation.

Conclusions:

• A mixed amine system of EDA and AEEA is a viable, low vapor pressure alternative for EMAR.
• This mixed amine system offers improved energetics and stable performance for CO2 capture.
• The findings provide a guideline for developing advanced EMAR processes for flue gas treatment and other CO2 sources.