The Chemistry of CO₂ Capture in an Amine-Functionalized Metal–Organic Framework under Dry and Humid Conditions

The use of two primary alkylamine functionalities covalently tethered to the linkers of IRMOF-74-III results in a material that can uptake CO₂ at low pressures through a chemisorption mechanism. In contrast to other primary amine-functionalized solid adsorbents that uptake CO₂ primarily as ammonium carbamates, we observe using solid state NMR that the major chemisorption product for this material is carbamic acid. The equilibrium of reaction products also shifts to ammonium carbamate when water vapor is present; a new finding that has impact on control of the chemistry of CO₂ capture in MOF materials and one that highlights the importance of geometric constraints and the mediating role of water within the pores of MOFs.