Kinetic Reaction Characteristics of Quasi-Aqueous and Nonaqueous Sorbents for CO₂ Absorption Using MEA/H₂O/Ethylene Glycol

We lowered the amount of water used in the solvent to 50% or less and examined the physical characteristics of quasi-aqueous and nonaqueous sorbents using an organic solvent with a high specific heat, instead of water. The physical solubility, diffusivity, and CO 2 absorption rate were measured as a function of temperature (293, 303, 313, and 323 K) and sorbent (monoethanolamine, MEA/H 2 O; quasi-aqueous MEA/H 2 O/ethylene glycol; nonaqueous MEA/ethylene glycol). Results show that the rate of CO 2 absorption by the nonaqueous sorbent increases with temperature and ethylene glycol content. Rate constants for CO 2 absorption by the sorbents were evaluated based on the physical data and absorption rate. The reaction rate constants of the water-based, quasi-aqueous, and nonaqueous sorbents were determined to be ∼698, ∼1518, and ∼1780 m 3 kmol –1 s –1, respectively. Furthermore, the CO 2 absorption–regeneration efficiency and CO 2 loading amount were evaluated during continuous CO 2 absorption and sorbent regeneration.