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

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