Understanding Solvent Degradation in CO₂ Capture – CESAR1 Solvent Degradation in Pilot and Laboratory Scale

by | Jan 9, 2025

The fight against climate change requires innovative solutions, and one promising method is CO₂ capture and storage (CCS). CCS involves capturing carbon dioxide from industrial emissions before it reaches the atmosphere. At the heart of this process are specialized chemical solvents, such as CESAR1, which absorb CO₂ from flue gases.

While CESAR1 has shown great promise for CO₂ capture, scientists are still working to understand how it behaves under tough industrial conditions during long-term operation. This includes studying a phenomenon called solvent degradation—the breakdown of the solvent over time. A recent study by SINTEF, coordinator of the AURORA project, in collaboration with NTNU and TCM sheds light on this process. 

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What is CESAR1?

CESAR1 is a blend of two amines (a type of chemical compound):

  1. 2-amino-2-methyl-propanol (AMP)
  2. Piperazine (PZ)

These compounds work together to absorb CO₂ efficiently while being more stable than older solvents like ethanolamine (MEA).

However, even CESAR1 can degrade when exposed to heat, oxygen, and other reactive chemicals found in industrial flue gases. Understanding this degradation is crucial for improving the solvent’s efficiency, reducing environmental impact, and minimizing costs.

What Did the Study Explore?

Scientists analyzed CESAR1 samples that had been used in a pilot CO₂ capture plant. They aimed to identify the byproducts of degradation, understand their chemical structure, and pinpoint how they form.

Using advanced analytical techniques, researchers identified 35 different degradation compounds in the CESAR1 samples. Among these, 12 compounds were completely new discoveries, never previously linked to CESAR1 or its components, AMP and PZ.

Key Findings

  1. Nitrogen Tracking
    • CESAR1 contains nitrogen, a critical element in its chemical structure. The researchers analyzed nitrogen levels in the original solvent and its degradation byproducts. By quantifying nitrogen in known and identified degradation products, they accounted for 99% of the nitrogen from the degraded solvent. This high recovery rate highlights the effectiveness of their methodology and helps ensure that no significant or abundant degradation compounds are overlooked—an important step forward compared to previous methods, which could only identify around 2% of nitrogen-containing byproducts. 
  2. New Degradation Compounds:
    • Two newly discovered compounds, HMeGly and AEAAC, were found in significant amounts. These compounds form during degradation, but their exact formation mechanisms remain a mystery.
  3. Better Insights into Reactions:
    • The study compared real-world CESAR1 samples from a pilot plant to laboratory experiments. This helped identify the conditions that cause certain reactions to occur.

Why does this matter?

Degradation can reduce a solvent’s efficiency, increase costs, and even pose safety risks. For example:

  • Efficiency: Degradation products can interfere with the solvent’s ability to absorb CO₂.
  • Costs: Replacing degraded solvent and maintaining equipment increases operational expenses.
  • Environmental Impact: In the unlikely event that some degradation products are released into the atmosphere, it is essential to assess their potential environmental impact and ensure they are benign. 

By identifying and quantifying degradation compounds, this research provides crucial insights that help us operate the process as safely and cost-efficiently as possible, ensuring the continued viability of CO₂ capture technologies. 

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The Authors

  • SINTEF Industry, NO-7465 Trondheim, Norway: Vanja Buvik, Andreas Grimstvedt, Kai Vernstad, Merete Wiig;
  • Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), N-7497- Trondheim, Norway: Hanna K. Knuutila;
  • Technology Centre Mongstad, NO-5954 Mongstad, Norway: Muhammad Zeeshan, Sundus Akhter, Karen K. Høisæter, Fred Rugenyi, Matthew
    Campbell.

What’s next?

This study is a big step forward, but there’s still more to learn. Researchers will continue exploring how CESAR1 breaks down and how to minimize degradation. This knowledge is vital as we scale up CCS technologies to combat climate change.

The AURORA project and its partners are committed to advancing the science behind CCS and contributing to a cleaner, greener future.

See Our Results

Closing Knowledge Gaps – Density and Viscosity of Unloaded and CO2-loaded Aqueous AMP-PZ blends  

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AURORA’s latest scientific journal publication provides experimental density and viscosity data on different unloaded and CO2-loaded aqueous blends of  2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) used for absorption-based CO2 capture. The paper also provides correlations for density and viscosity suitable for various modelling works.In our previous review article, we identified knowledge…