Incomplete CO₂ Desorption Enhances O₂ Stability of Solid Amine Carbon Capture Sorbents

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Reducing carbon dioxide (CO2) emissions is crucial for environmental protection.
• Solid polyethylenimine (PEI) sorbents are promising for CO2 capture but suffer from instability in oxygen-containing flue gas.
• Oxidative degradation limits the industrial application of PEI-based CO2 sorbents.

Purpose of the Study:

• To develop an oxygen-stable solid polyethylenimine (PEI) sorbent for carbon dioxide (CO2) capture.
• To investigate a method for mitigating the oxidative degradation of PEI sorbents.
• To establish a tunable degradation rate for PEI sorbents based on working capacity.

Main Methods:

• Reduced CO2 desorption per cycle to form protective carbamates on PEI.
• Evaluation of sorbent stability under oxygen-containing gas mixtures.
• Quantification of degradation rate constant (kdeac) and working capacity.

Main Results:

• The proposed method significantly reduces oxidative cleavage, maintaining a low degradation rate (kdeac = -0.00373 cycle-1).
• A stable working capacity of 2.88 wt% (0.65 mmol g-1) was achieved under oxygen exposure.
• The degradation rate was found to be tunable by adjusting the sorbent's working capacity.

Conclusions:

• Reducing CO2 desorption per cycle effectively protects PEI amines from oxidative degradation.
• This additive-free approach enhances the oxidative stability of PEI sorbents for carbon capture.
• Tunable degradation offers potential for optimizing PEI sorbent performance in industrial processes.