Novel biphasic solvent of AEP/1-propanol/H2O for CO2 capture with efficient regeneration performance and low energy consumption

Abstract

Biphasic solvents have been attracting increasing attention in CO2 capture recently due to its energy-saving potential. However, most current biphasic solvents still face the problem of limited desorption performance. To solve the problem, a novel biphasic solvent of 1-(2-aminoethyl)piperazine (AEP)/1-propanol/H2O solution was proposed. The absorption capacity was 1.26 mol CO2·mol−1 amine, which was 2.3 times that of MEA. The regeneration efficiency was 74% and the cyclic capacity after 5 absorption-desorption experiments was 0.90 mol CO2·mol−1 amine, which was 2.7 times that of MEA. The absorption-desorption performance of AEP/1-propanol/H2O solution was much better compared with most current biphasic solvents. Meanwhile, AEP/1-propanol/H2O solution had a low regeneration heat of 2.74 GJ·t−1-CO2, which was 27.9% lower than that of MEA. Moreover, 13C NMR analysis was used to investigate the absorption-desorption mechanism and species distribution. The multiple amino groups in AEP could react with CO2 to produce carbamate and carbonate. The generated absorption products were mainly concentrated in the CO2-rich phase, while the CO2-lean phase contained much 1-propanol. Most of the absorption products were decomposed during regeneration, so the high desorption performance was achieved. Overall, AEP/1-propanol/H2O solution is a promising energy-saving candidate for industrial CO2 capture due to its competitive absorption-desorption performance and low regeneration energy.