Rapid Synthesisof Ultramicroporous Potassium-PyrenetetracarboxylateFramework 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.