Evaluation of the Quantity of CO2 Absorbed by an Aqueous Amine Solution

Significance of the Topic

Global efforts to achieve carbon neutrality have intensified the search for efficient CO2 separation and recovery methods. Aqueous amine-based absorption processes offer high reactivity and favorable recovery energy requirements, making them crucial for carbon capture and utilization strategies.

Objectives and Study Overview

This study evaluates the performance of an aqueous 2-Amino-2-methyl-1-propanol (AMP) solution for CO2 absorption using two Shimadzu analyzers. The aim is to quantify real-time CO2 uptake dynamics and determine the concentration of absorbed inorganic carbon, facilitating the optimization of amine-based capture systems.

Applied Methodology

CO2 gas at 4.78 vol% in N₂ was passed through an impinger containing 0.6 mL of 20 wt% AMP solution at 100 mL/min.
The real-time outlet CO2 concentration was recorded with the transportable CGT-7100 gas analyzer.
An overflow flow of 30 mL/min bypassed the impinger to maintain stable system pressure.

Used Instrumentation

• Shimadzu CGT-7100 Transportable Gas Analyzer: Continuous monitoring of CO2 outlet concentration over time.
• Shimadzu TOC-L Total Organic Carbon Analyzer: Quantitative determination of inorganic carbon (as HCO3−) in the post-absorption liquid through acidification and IR CO2 detection.

Main Results and Discussion

CO2 concentration profiles revealed incomplete absorption, reflecting limited gas–liquid contact and decreasing AMP reactivity over time.
Integration of the absorption curve yielded 24 231 vol%·sec of CO2 uptake, corresponding to 10 502 mg/L of inorganic carbon assuming full conversion to HCO3−.
TOC-L measurements on a 20× diluted sample gave 561.6 mg/L, equivalent to 11 232 mg/L in the original solution, closely matching the CGT-7100 estimate.
These consistent results confirm that reaction (2) (R-NH2 + CO2 + H2O ⇔ R-NH3+ + HCO3−) predominates for AMP under the tested conditions.

Benefits and Practical Applications

• Real-time monitoring of CO2 absorption kinetics informs reactor design and process control.
• Accurate quantification of absorbed inorganic carbon supports amine capacity assessment and regeneration energy calculations.
• Scalable analysis suitable for laboratory R&D and pilot-plant scale evaluations.

Future Trends and Opportunities

Integration of advanced mixing and mass-transfer enhancement techniques can improve absorption efficiency.
Automation of sampling and multi-component analysis with syringe injection kits for TOC-L can extend applications to complex gas streams.
Combining gas analyzers with process simulation and machine learning may optimize absorber-stripper network design.

Conclusion

The synergy of the CGT-7100 and TOC-L instruments enables comprehensive investigation of CO2 absorption in aqueous amines, providing both dynamic gas‐phase data and precise liquid‐phase carbon quantification. This dual approach facilitates effective development and scale-up of carbon capture processes.

References

1) Teranishi K., Ishikawa A., Nakai H. J. Comput. Chem. Jpn., 15(2), A15–A29 (2016).
2) Iijima M., Endo T., Shimada D. Mitsubishi Heavy Industries Technical Review, 47(1) (2010).