Efficient Absorption of CO₂ by Protic-Ionic-Liquid Based Deep Eutectic Solvents

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Carbon capture, utilization, and storage (CCUS) are crucial for global emission reduction.
• Deep eutectic solvents (DESs) are emerging as promising, designable solvents for CO2 capture.

Purpose of the Study:

• To synthesize and investigate binary DESs composed of protic ionic liquid (PIL) and amine for CO2 capture.
• To evaluate the performance of these DESs compared to industrial standards.

Main Methods:

• One-step synthesis of binary DESs from PIL and amine.
• Measurement of melting points to confirm eutectic behavior.
• Quantification of CO2 absorption capacity and rate constants.
• Analysis of CO2 interaction enthalpy and absorption mechanism via NMR.
• Assessment of regeneration efficiency through multiple absorption/desorption cycles.

Main Results:

• Synthesized DESs exhibit high CO2 absorption capacity (0.1 g/g at 1.0 bar, 25°C).
• Superior apparent absorption rate constants (0.381 min⁻¹) compared to MDEA (0.012 min⁻¹).
• Moderate CO2 interaction enthalpy (as low as -34.8 kJ/mol) and good reversibility over eight cycles.

Conclusions:

• The synthesized DESs offer a convenient and effective alternative for CO2 capture.
• Their high capacity, fast kinetics, moderate interaction, and excellent regeneration position them as potential industrial absorbents.