My question is that if we want to remove CO2 from a gas stream that contains 20% O2 and less than 5% CO2, what are the best solvents list? The solvent should be able to remove CO2 in very low concentration (i.e. 2.5%) and has resistant to oxidative degradation. What do you suggest?
Shervan Babamohammadi , I would not suggest using any typical amines like MEA, MDEA or PZ due to the high concentration of oxygen in the gas. If you are not planning to reuse the solution, you can simply use KOH solution to capture CO2. Otherwise, typical amino acid solutions (e.g., GlyK or SarK) can be used with a high CO2 capacity and good recycability at your conditions. I hope it helps.
Hi Masood S. Alivand, thank you for your response! What is the main issue with KOH being used in cyclic absorption? Is the regeneration very costly?
And, is it possible to use the typical amino acids for low CO2 concentrations (below 5% v/v)?
The recyclability of KOH needs a high temperature and energy, resulting in a moderate cyclic capacity. However, it is still one of the options and can be used to capture low concentrations of CO2. Actually, 5% CO2 is not that low and amino acids can easily capture this level of CO2. You can find the equilibrium CO2 uptake of different amino acids (isotherms at different CO2 partial pressures) in literature.
Maybe of some interest for your query:
https://www.researchgate.net/post/How-we-can-increase-solubility-of-gases-O-or-CO2-in-liquid-water-chemically
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