Mixture Absorption System of Monoethanolamine Triethylene Glycol for CO2 Capture

In this paper, a mixture system without water but composed of monoethanolamine (MEA) and triethylene glycol (TEG) is designed for CO2 capture. The solubility of CO2 in pure TEG and MEA-TEG solutions is determined, respectively, showing that the solubility of CO2 in TEG is generally consistent with Henry's Law and the value is higher than that in water. The solubility of CO2 in MEA-TEG solutions significantly increases with the increase of MEA, showing the characteristics of chemical reaction absorption. The absorption mechanism study shows that TEG does not act as a reaction agent. There is only one reaction between CO2 and MEA. The absence of water in the new system leads to the absence of dissociation of protonated MEA and formation of carbamate (MEACOO(-)). This is much different from the MEA-water system. A mathematical model is also developed for predicting the solubility of CO2 in the new system. The results show that the absorption and desorption can be realized at relatively lower temperatures (lower than 353.15 K), which may provide advancement in two aspects: low energy consumption with less solvent evaporation and avoidance of MEA's degradation caused by high-temperature operation.