CO₂ capture using mixed amines: experimental DFT investigation with focus on improvements in cyclic efficiency and NO...

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Post-combustion carbon dioxide (CO2) capture is crucial for mitigating emissions from power plants and marine vessels.
• Developing efficient and robust absorbent systems is key to effective CO2 reduction strategies.

Purpose of the Study:

• To comparatively evaluate hybrid amine blends for CO2 capture under simulated marine engine flue gas conditions.
• To investigate the impact of nitrogen oxides (NO) on the performance of these blends.
• To elucidate molecular interactions and bonding mechanisms using computational methods.

Main Methods:

• Testing of N-methyldiethanolamine (MDEA) based hybrid blends (with MEA, TEPA, AMP, PZ) under simulated marine flue gas conditions, including exposure to NO.
• Density Functional Theory (DFT) calculations, including Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), Electron Density Difference (EDD), and Non-Covalent Interaction (NCI) analyses.

Main Results:

• The TEPA+MDEA blend exhibited the highest initial CO2 absorption, but NO significantly reduced its capacity.
• The AMP+MDEA blend showed an unexpected increase in CO2 absorption in the presence of NO, highlighting complex interactions.
• DFT analyses indicated decreased HOMO-LUMO energy gaps and charge transfer from CO2 to the blends, suggesting enhanced reactivity and van der Waals interactions.

Conclusions:

• Hybrid amine blends offer potential for CO2 capture, but their performance is sensitive to contaminants like NO.
• Computational chemistry provides valuable insights into molecular interactions, aiding the design of advanced CO2 capture materials.
• Further research into mixed absorbents and contaminant effects is essential for developing sustainable CO2 capture technologies.