Evaluating the Performance of Micro-Encapsulated CO2 Sorbents during CO2 Absorption and Regeneration Cycling

We encapsulated six solvents with novel physical and chemical properties for CO 2 sorption within gas-permeable polymer shells, creating Micro-Encapsulated CO 2 Sorbents (MECS), to improve the CO 2 absorption kinetics and handling of the solvents for postcombustion CO 2 capture from flue gas. The solvents were sodium carbonate (Na 2 CO 3 ) solution, uncatalyzed and with two different promoters, two ionic liquid (IL) solvents, and one CO 2 -binding organic liquid (CO 2 BOL). We subjected each of the six MECS to multiple CO 2 absorption and regeneration cycles and measured the working CO 2 absorption capacity as a function of time to identify promising candidate MECS for large-scale carbon capture. We discovered that the uncatalyzed Na 2 CO 3 and Na 2 CO 3 -sarcosine MECS had lower CO 2 absorption rates relative to Na 2 CO 3 -cyclen MECS over 30 min of absorption, while the CO 2 BOL Koechanol appeared to permeate through the capsule shell and is thus unsuitable. We rigorously tested the most promising three MECS (Na 2 CO 3 -cyclen, IL NDIL0309, and IL NDIL0230) by subjecting each of them to a series of 10 absorption/stripping cycles. The CO 2 absorption curves were highly reproducible for these three MECS across 10 cycles, demonstrating successful absorption/regeneration without degradation. As the CO 2 absorption rate is dynamic in time and the CO 2 loading per mass varies among the three most promising MECS, the process design parameters will ultimately dictate the selection of MECS solvent.