Implementation of a Core-Shell Design Approach for Constructing MOFs for CO Capture.

Adsorption-based capture of CO from flue gas and from air requires materials that have a high affinity for CO and can resist water molecules that competitively bind to adsorption sites. Here, we present a core-shell metal-organic framework (MOF) design strategy where the core MOF is designed to selectively adsorb CO, and the shell MOF is designed to block HO diffusion into the core. To implement and test this strategy, we used the zirconium (Zr)-based UiO MOF platform because of its relative structural rigidity and chemical stability.

Designing optimal core-shell MOFs for direct air capture.

Metal-organic frameworks (MOFs), along with other novel adsorbents, are frequently proposed as candidate materials to selectively adsorb CO for carbon capture processes. However, adsorbents designed to strongly bind CO nearly always bind HO strongly (sometimes even more so). Given that water is present in significant quantities in the inlet streams of most carbon capture processes, a method that avoids HO competition for the CO binding sites would be technologically valuable.

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.