Screening test for aqueous solvents used in CO₂ capture: K₂CO₃ used with twelve different rate promoters

K₂CO₃ solution is widely used in the CO₂-capture industry. In particular, it has advantages for treating CO₂ in flue gas under high-temperature and high-pressure conditions. However, it has a lower CO₂-loading capacity and slower absorption kinetics than those of amines, which are its major disadvantages. Thus, in this study, we investigated ten loading-rate promoters, five primary amines and five secondary amines, to develop higher CO₂-loading capacity and faster absorption kinetics. The screening tests of the absorption and desorption processes were conducted at 70 °C and 90 °C, respectively. Based on the results, we concluded that all the amines used improved the CO₂-loading and absorption kinetics compared with the use of K₂CO₃ alone. At a certain value CO₂ loading, the respective performance of the primary and secondary amines was twice and thrice better, respectively, than the neat K₂CO₃ solution. Thus, secondary amines had superior absorption capacity and absorption/desorption rate compared to primary amines. Among the secondary amines, pipecolic acid, sarcosine, and isonipecotic acid were determined as the most effective absorption rate promoters.