Solubility of CO2 in the Mixed Solvent System of Alkanolamines and Poly(ethylene glycol) 200

Mixed solvents of monoethanolamine (MEA), diglycolamine (DGA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) with poly(ethylene glycol) 200 (PEG200) as cosolvent were analyzed by thermal gravimetric analysis to select an available CO2 absorber. MEA-PEG200 has the lowest onset temperature (the temperature at which the weight loss begins) of 363 K and thus is not appropriate for CO2 capture at high temperature. The viscosities of the mixtures decrease as temperature increases, and are mainly decided by the viscosity of PEG200 at a high temperature. The solubility of CO2 in mixed solvents of alkanolamine (DGA, DEA, and MDEA) and PEG200 was measured over the range of pressure from (10 to 1600) kPa and temperature from (313.15 to 393.15) K in intervals of 40 K DEA and DGA solutions show relatively high CO2 capacity at 313.15 K owing to a chemical reaction with CO2, while MDEA solution presents the property of physical absorber. When temperature further increases to 393 K, the capacity decreases significantly. The solubility was correlated by Jou and Mather's model.