Microencapsulation of advanced solvents for carbon capture

Abstract

Purpose-designed, water-lean solvents have been developed to improve the energy efficiency of CO₂ capture from power plants, including CO₂-binding organic liquids (CO₂BOLs) and ionic liquids (ILs). Many of these solvents are highly viscous or change phases, posing challenges for conventional process equipment. Such problems can be overcome by encapsulation. Micro-Encapsulated CO₂ Sorbents (MECS) consist of a CO₂-absorbing solvent or slurry encased in spherical, CO₂-permeable polymer shells. The resulting capsules have diameters in the range of 100–600 μm, greatly increasing the surface area and CO₂ absorption rate of the encapsulated solvent. Encapsulating these new solvents requires careful selection of shell materials and fabrication techniques. We find several common classes of polymers are not compatible with MECS production, but we develop two custom formulations, a silicone and an acrylate, that show promise for encapsulating water-lean solvents. We make the first demonstration of an encapsulated IL for CO₂ capture. The rate of CO₂ absorption is enhanced by a factor of 3.5 compared to a liquid film, a value that can be improved by further development of shell materials and fabrication techniques.