Inhibiting effect of 2-amino-2-methyl-1-propanol on gelatinous product formation in non-aqueous CO2 absorbents: Experimental study and molecular understanding.

[Display omitted] • A strategy that using AMP as a gelatinous product inhibitor in NNAs was proposed. • AMP-regulated NAAs did not yield insoluble gelatinous products during CO 2 absorption. • AMP-regulated NAAs featured good CO 2 capture performance. • CO 2 absorption mechanism was studied based on 13C NMR and theoretical calculations. • The inhibitory mechanism of AMP on the formation of gelatinous products was clarified. Diamines or polyamines with two or more amino groups are suitable for formulating non-aqueous absorbents (NAAs) with high CO 2 loading capacity and low regeneration energy consumption. However, these two types of amines in NAAs are prone to produce insoluble gelatinous products after absorbing CO 2 , resulting in difficult operation of the CO 2 capture system. In this study, by using 2-amino-2-methyl-1-propanol (AMP) as an inhibitor, the insoluble gelatinous products of the aminoethylethanolamine (AEEA)-N-methyl-2-pyrrolidone (NMP) (A-A-N) and 3-(methylamino)propylamine (MAPA)-NMP (M-A-N) NAAs were successfully eliminated. The experimental results showed that the AMP-regulated NAAs possessed a high absorption rate, high CO 2 loading capacity, excellent desorption efficiency, and stable recyclability. The reaction mechanism of CO 2 absorption and the inhibitory mechanism of AMP on the formation of gelatinous products were comprehensively elucidated. Taking the A-A-N system as a representative, AEEA reacted with CO 2 to form zwitterionic protonated carbamate species (AEEACO 2 − (P) H+ (S)), which tended to self-aggregate via hydrogen-bond interaction, resulting in the formation of insoluble gelatinous products. With the introduction of AMP, the AMP-derived products could combine easily with AEEACO 2 − (P) H+ (S) via strong electrostatic attraction to form ion pairs, preventing the AEEACO 2 − (P) H+ (S) molecules from self-aggregating to form insoluble gelatinous products. The regeneration heat duty of the A-A-N system was 1.89 GJ∙ton−1 CO 2 , which was 49.9 % lower than that of the benchmark 30 wt% MEA. Overall, introducing AMP as a gelatinous product inhibitor was beneficial for the development of NNAs with high CO 2 absorption capacity and low-energy consumption. [ABSTRACT FROM AUTHOR]