Carbon Dioxide Absorption by Polyethylene Glycol Dimethyl Ether Modified by 2-methylimidazole

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Developing and utilizing capture and storage technologies for CO2 has become a critical research topic due to the significant greenhouse effect caused by excessive CO2 emissions. A conventional physical absorption process for CO2 capture is polyethylene glycol dimethyl ether (NHD); however, its limited application range is caused by its poor absorption of CO2 at low pressures. In this work, the CO2 absorption of NHD was enhanced by combining NHD with a novel chemical absorbent 2-methylimidazole (2-mIm)-ethylene glycol (EG) solution to improve CO2 absorption. Viscosity and CO2 solubility were examined in various compositions. The CO2 solubility in the mixed solution was found to be at maximum when the mass fractions of NHD, 2-mIm, and EG were 20%, 40%, and 40%, respectively. In comparison to pure NHD, the solubility of CO2 in this mixed solution at 30 °C and 0.5 MPa increased by 161.2%, and the desorption heat was less than 30 kJ/mol. The complex solution exhibits high selectivity and favorable regeneration performance in the short term. However, it is more sensitive to moisture content. The results of this study can provide important data to support the construction of new low-energy solvent systems and the development of novel CO2 capture processes.