Effect of sterically hindered amines on the cycling capacity of biphasic absorbents for industrial CO2 capture.

The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO2 capture. However, most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase. To the issues, a novel pentamethyldiethylenetriamine (PMDETA)-2-amino-2-methyl-1-propanol (AMP)/diethylenetriamine (DETA)-sulfolane biphasic solvent was developed. The mechanism of AMP affecting CO2 recycling capacity was analyzed. By adjusting the ratio of AMP and DETA, the absorption and desorption performance were balanced, and the recycling capacity and renewable energy consumption of the absorbent were improved. For the P2.4A0.8D0.8S2 biphasic solvent, the CO2 loading of the rich phase was 5.87 mol/L, and the proportion of the rich phase volume ratio was 35%, which surpasses most reported biphasic solvents. The viscosity of the absorbent significantly decreased from 527.00 mPa·s to 92.26 mPa·s, attributed to the beneficial effect of AMP. Thermodynamic analysis showed that the biphasic solvent produced a lower regeneration energy consumption of 1.70 GJ/t CO2, which was 57% lower than that of monoethanolamine (MEA). Overall, the PMDETA-AMP/DETA-sulfolane biphasic solvent exhibited cycle capacity, which provided new insights for the designing of biphasic solvent.