Enhancing capture performance of physical solvent biphasic absorbent using TEPA as activator for efficient CO2 capture from flue gas

The low capture loading is one of the main issues in developing the physical solvent biphasic absorbent. To address this issue, a small amount of polyamine TEPA was introduced as an activator into the DMAPA-Sulfolane-H 2 O (DSH) solution, aiming to design a novel diamine-based physical solvent biphasic absorbent DSH-TEPA for efficient CO 2 capture from flue gas in this study. The enhancement of TEPA on the phase separation and the capture performance was illustrated by experiments and molecular simulations. Experimental results revealed that DSH-0.20 M TEPA presented excellent enhancement performance for CO 2 capture: increased by 18.6 % of the absorption loading, 19.4 % of the rich phase loading, 7.8 % of the amine availability, 12.3 % of the overall mass transfer coefficient, 17.5 % of the desorption loading when comparing with DSH. In addition, DSH-0.2 M TEPA could achieve regeneration energy as low as 2.045 GJ/t CO 2 , which was 42.8 % lower than 30 wt% MEA, and lower than most of the reported physical solvent biphasic absorbents. For the application test, an increase in the CO 2 concentration in the flue gas could effectively increase the absorption rate and loading while there was an optimal gas flow rate for a certain CO 2 concentration to obtain higher capture performance. The enhancement mechanism of TEPA was analyzed elaborately by 13 C NMR characterization and quantum chemistry calculations and 134 possible types of TEPA-derived products were depicted according to the unique structure of TEPA. The higher polarity of TEPA-derived products and the stronger hydrogen bonds between TEPA-derived products and H 2 O confirmed the TEPA role as not only an excellent capture loading activator but also an effective phase separation accelerator.