High-Throughput Screening and Kinetic Analysis of CO₂ Absorbents via Optical Reflection Imaging

Area of Science:

• Chemical Engineering
• Environmental Science
• Analytical Chemistry

Background:

• Fossil fuels continue to dominate global energy, necessitating effective carbon dioxide (CO2) emission mitigation strategies.
• Post-combustion capture using chemisorption is a key technology, but understanding absorption kinetics is vital for optimizing solvent performance.
• Accurate kinetic data is crucial for both fundamental reaction mechanism elucidation and practical application development.

Purpose of the Study:

• To develop and validate a novel, high-throughput optical imaging platform for in situ visualization of CO2 absorption kinetics in liquid absorbents.
• To quantitatively compare the absorption capacities and kinetic parameters of different alkanolamine solvents.
• To elucidate the distinct reaction mechanisms and kinetics of primary, secondary, and tertiary amine absorbents.

Main Methods:

• A prism-based reflection optical imaging platform was integrated with a multichannel gas-injection system.
• CO2 absorption was visualized by detecting changes in reflected light intensity due to refractive index variations.
• High-throughput screening allowed for direct comparison of absorption performance and kinetic parameters of various amine solutions.

Main Results:

• The optical imaging platform successfully visualized and quantified dynamic CO2 absorption in real-time.
• Monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) were analyzed, revealing distinct kinetic behaviors.
• Primary and secondary amines showed similar pathways but different rates, while tertiary amines exhibited a unique mechanism with higher concentration dependence.

Conclusions:

• Reflection-based optical imaging offers a low-cost, versatile platform for high-throughput screening of gas-liquid absorption kinetics.
• The findings provide critical insights into the reaction kinetics and mechanisms of different amine classes for CO2 capture.
• This approach can guide data-driven discovery and optimization of novel absorbent materials for efficient carbon capture.