Comparative Study of CO₂ Capture by Aqueous and Nonaqueous 2-Amino-2-methyl-1-propanol Based Absorbents Carried Out by ¹³C NMR and Enthalpy Analysis

The CO2 uptake by single 2-amino-2-methyl-1-propanol (AMP) and its blends with 2-(ethylamino)ethanol (EMEA) or N-methyl-2,2’-iminodiethanol (MDEA) has been investigated both in aqueous and non-aqueous solutions, and compared with aqueous 2-aminoethanol (MEA), the most used sorbent in CCS processes. The loading capacity, the rate of absorption and the heat of CO2 absorption have been experimentally determined for all the amine solutions. 13C NMR analysis allowed the identification of the carbonated species formed in solution and to evaluate their relative amount. The most promising sorbents have been further tested in a continuous cycle of absorption and desorption carried out in packed columns, in order to verify their CO2 (15% in N2) capture efficiency. Thanks to their good CO2 loading, high rate of reaction with CO2 and low heat of absorption, the AMP-EMEA blend solutions, both in water and in organic diluents, are good candidates for CO2 capture as an alternative to the conventional aqueous MEA solution.