CO₂ absorption and microwave regeneration with high-concentration TETA nonaqueous absorbents

While nonaqueous organic-amine absorbents have great potential in reducing energy consumption of CO₂ capture, their absorption/desorption behaviors are still poorly understood when high-concentration polyamines are used. On the other hand, large scale CO₂ capture demands the use of high-concentration polyamines absorbents. Therefore, we investigated the absorption and microwave regeneration behavior of high-concentration triethylenetetramine (TETA) in three typical organic solvents, including polyethylene glycol 200 (PEG200), diethylene glycol (DEG), and ethylene glycol (EG). The results showed that high-concentration TETA nonaqueous absorbents demonstrate advantages in absorption rate and regeneration energy consumption. The average absorption rate of 2.0 and 5.0 mol/L TETA/EG was 2.84 and 4.70 times that of 0.6 mol/L, respectively. The energy consumption of TETA/EG and TETA/DEG decreased by 29.4 and 25.6% as the concentration increased from 0.6 to 5.0 mol/L. In addition, the high-concentration TETA/PEG200 absorbent demonstrated observable tolerance for water vapor, which usually exists in flue gas. Results also showed that microwave regeneration was superior to conventional conduction heating especially when high-concentration TETA/PEG200 absorbent were used. The energy consumption of microwave regeneration of the absorbent with a concentration of 0.6, 2.0, and 5.0 mol/L was reduced by 65.9, 81.2, and 86.0%, respectively when compared with conduction heating.