Pyrazine‐interior‐embodied MOF‐74 for selective CO₂ adsorption

Abstract

A series of pyrazine-interior-embodied metal-organic framework-74 composites (py-MOF-74) were successfully synthesized by a post-synthetic vapor modification method. Here, pyrazine molecules occupy the cavity to block the wide pores of MOF-74, which accentuates the difference in adsorption of a pair of gases on MOFs and consequently reinforces the adsorption selectivity. Different from the "physical confinement" of occupants, the pyrazine molecule with dual "para-nitrogen" atoms donates one N atom to bond with the open metal ion of MOF-74 for stability and the other N atom for potential CO 2 trapping. Typically, py-MOF-74c with the highest pyrazine insertion ratio displays selectivity greatly superior to that of MOF-74 in equimolar CO 2 /CH 4 (598 vs. 35) and in simulated CO 2 /N 2 flue gas (471 vs. 49). Py-MOF-74 entities are long-lived adsorbents, and their CO 2 capacity can be maintained even after storage for 1 year in air. Py-MOF-74 also showed a sharp molecular sieve property in fixed-bed cycle adsorption tests, which implies its great potential in real applications.

Sustainable and scalable continuous synthesis of metal‐organic frameworks for CO2 capture

“…In general, there are three methods to mitigate CO 2 emissions, namely, post‐combustion, pre‐combustion and oxy‐fuel combustion capture 4,5 . Among these, post‐combustion is more favorable for existing power plants as this approach only affects the flue gas and avoids substantial modifications to the plants 6,7 . Current post‐combustion carbon capture systems use amine scrubbers, which result in an energy of 25–40% during plant operation 2 .…”

“…4,5 Among these, post-combustion is more favorable for existing power plants as this approach only affects the flue gas and avoids substantial modifications to the plants. 6,7 Current post-combustion carbon capture systems use amine scrubbers, which result in an energy of 25-40% during plant operation. 2 Since such amine scrubbers are not an efficient or economical way to reduce CO 2 emission, 2nd generation sorbents might offer a solution to the energy demand issue.…”