Aqueous ethylenediamine for CO(2) capture.

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Carbon dioxide (CO2) capture is crucial for mitigating climate change.
• Aqueous amine solutions are widely studied for CO2 absorption.
• Ethylenediamine (EDA) is explored as a potential solvent for CO2 capture.

Purpose of the Study:

• To evaluate aqueous ethylenediamine (EDA) as a solvent for CO2 capture from flue gas.
• To assess EDA's performance characteristics including capacity, absorption rate, viscosity, and thermal stability.
• To compare EDA's performance with established solvents like monoethanolamine (MEA).

Main Methods:

• Investigated 12 M aqueous EDA for CO2 capture.
• Measured viscosity, CO2 loading capacity, and absorption rates.
• Assessed thermal degradation at temperatures up to 120°C.
• Evaluated the effect of an inhibitor on oxidative degradation.
• Determined the apparent heat of CO2 desorption.

Main Results:

• 12 M EDA exhibits acceptable viscosity (16 cP) and CO2 loading (0.48 mol CO2/equiv EDA).
• EDA is stable up to 120°C, with degradation occurring above this temperature.
• Oxidative degradation does not cause excessive foaming, unlike piperazine.
• CO2 absorption rate is comparable to 7 M MEA over much of the loading range, but slower at rich loading.
• EDA has a CO2 capacity of 0.72 mol CO2/(kg H2O+EDA), double that of MEA.
• Apparent heat of CO2 desorption is 84 kJ/mol CO2.

Conclusions:

• Aqueous EDA is a promising solvent for CO2 capture, offering high capacity and good thermal stability.
• EDA's performance, particularly its capacity, makes it a competitive alternative to MEA.
• Further research into optimizing EDA for faster rich loading absorption rates is warranted.