Monodentate hydroxide as a super strong yet reversible active site for CO2 capture from high-humidity flue gas

Abstract

We demonstrate here that porous coordination frameworks, functionalized with monodentate hydroxide on the pore surface, can achieve ultrahigh CO₂ adsorption affinity (124 kJ mol⁻¹), adsorption capacity (9.1 mmol cm⁻³ at 298 K and 1 bar), and CO₂/N₂ selectivity (262 at 298 K) by the reversible formation/decomposition of bicarbonate in the adsorption/desorption processes. More importantly, these materials can capture up to 4.1 mmol cm⁻³ or 13.4 wt% of CO₂ from simulated flue gases (CO₂ pressure 0.10–0.15 bar at 313 K) even at high relative humidity (82%) and quickly release it under mild regeneration conditions (N₂ purge at 358 K), representing the best CO₂ capture performances reported to date.