Rapid Synthesis of Ultramicroporous Potassium-Pyrenetetracarboxylate Framework with Confined-Space-Charge-Driving CO2 Capture

Upgrading and optimizing carbon capture technology and materials may significantly enhance the development of industry. Herein, a specific confined-space-charge-driving CO2 capture strategy is pioneered in a MOF adsorbent, SNNU-117, an anionic potassium-pyrenetetracarboxylate complex obtained via a simple, mild, rapid, and scalable salting-out method. As expected, the regularly shaped ultramicropores (about 3.6 Å) comparable to those of CO2 molecules effectively restrict gas molecule reorientation, while the multiple active protons on the pore surface provide a positive electrostatic potential for polarized oxygen in CO2 molecules. Such synergy between pore size and electrostatic potential clearly promotes the CO2 adsorption and separation performance. Under 298 K, 1 bar, SNNU-117 exhibits high affinity for CO2 with exceptional IAST selectivity of CO2/C2H2 (2744), CO2/N2 (6.3 × 104), and CO2/CH4 (5.6 × 106) surpassing nearly all MOF adsorbents. Density functional theory (DFT) calculation, Grand Canonical Monte Carlo (GCMC) simulation, and dynamic breakthrough experiments further support the specific confined-space-charge-driving CO2 capture ability of SNNU-117.