Characterization and kinetics of carbon dioxide absorption into aqueous tetramethylammonium glycinate solution

An advanced aqueous amine solvent of tetramethylammonium glycinate ([N1 1 1 1][Gly]) was characterized for carbon dioxide (CO2) absorption purposes. Density, viscosity and pH of the [N1 1 1 1][Gly] solution, with concentrations ranging from 5% to 30%, were determined at temperatures from 298 to 323 K. Solubility and diffusivity of CO2 in [N1 1 1 1][Gly] solution at the same temperatures and concentrations was estimated. Absorption of CO2 into [N1 1 1 1][Gly] aqueous solution was investigated using a double stirred-cell absorber with a planar gas–liquid interface. The effects of the [N1 1 1 1][Gly] concentration, temperature and CO2 concentration of absorption CO2 into aqueous [N1 1 1 1][Gly] were studied. The kinetics study showed that absorption CO2 into aqueous [N1 1 1 1][Gly] was the fast pseudo-first order reaction regime. Based on the reaction regime, the enhancement factor E, the overall reaction kinetic constant kov and the second-order rate constant k2 were obtained using the two-film model. The results showed that E was linear with CB01/2, and the activation energy of 15% aqueous [N1 1 1 1][Gly] absorbing CO2 was 15.431 kJ mol−1.

► Low concentration of [N1 1 1 1][Gly] aqueous solution was favorable for CO2 absorption.
► [N1 1 1 1][Gly] aqueous solution was characterized for CO2 absorption purpose.
► [N1 1 1 1][Gly] aqueous solution absorbing CO2 was the fast pseudo-first order reaction.
► Enhancement factor was linear with square root of [N1 1 1 1][Gly] initial concentration.