A novel solid-liquid 'phase controllable' biphasic amine absorbent for CO2 capture

The main issues in the application of biphasic amine absorbent include the inconvenient separation of the liq-uid-liquid biphase and the clogging that is associated with the solid-liquid mixture. A novel solid-liquid 'phase controllable' biphasic amine absorbent was therefore developed, in which the phase separation occurred only when the absorbent was near saturation. The absorbent, composed of triethylene tetramine (TETA), 2-amino-2- methyl-1-propanol (AMP), and N-methylformamide (NMF), turned into solid-liquid biphase under CO2 loading of 0.85 mol mol1, which is close to saturation (0.92 mol mol1). The solid phase comprised white powder that accounted for only 42 % of the total volume while absorbing 91 % of the total load. Turbidity and particle size tests showed that the phase separation was self-aggregating. The mechanisms of absorption and regulation were obtained using 13C NMR and molecular simulation. During the absorption, CO2 first combined with TETA to generate TETAH+CO2-/TETACO2- through the zwitterion mechanism, and then combined with AMP to generate AMPCO2- because of the lower reaction activity between CO2 and AMP. The TETA-carbamate was found to greatly weakened the strength of the hydrogen bonds and the van der Waals forces between AMPH+and AMPCO2-, increasing the solubility of the intermediate products, and therefore achieved the purpose of con-trolling the phases separation inherent in the reaction.

Automated summary

The main challenges in the application of biphasic amine absorbent are the inconvenient separation of liquid-liquid biphasic and the clogging caused by solid-liquid mixture. A novel solid-liquid 'phase controllable' biphasic amine absorbent has been developed to address these issues.