A Microporous Co-MOF for Highly Selective CO₂ Sorption in High Loadings Involving Aryl C-H···O=C=O Interactions: Combined Simulation and Breakthrough Studies

In the context of porous crystalline materials toward CO₂ separation and capture, a new 2-fold interpenetrated 3D microporous Co-MOF, IITKGP-11 (IITKGP denotes Indian Institute of Technology Kharagpur), has been synthesized consisting of a 1D channel of ∼3.6 × 5.0 Ų along the [101] direction with a cavity volume of 35.20%. This microporous framework with a BET surface area of 253 m²g^-1 shows higher uptake of CO₂ (under 1 bar, 3.35 and 2.70 mmol g^-1 at 273 and 295 K, respectively), with high separation selectivities for CO₂/N₂ and CO₂/CH₄ gas mixtures under ambient conditions as estimated through IAST calculation. Moreover, real time dynamic breakthrough studies reveal the high adsorption selectivity toward CO₂ for these binary mixed gases at 295 K and 1 bar. Besides high gas separation selectivity, capacity considerations in mixed gas phases are also important to check the performance of a given adsorbent. CO₂ loading amounts in mixed gas phases are quite high as predicted through IAST calculation and experimentally determined from dynamic breakthrough studies. In order to get insight into the phenomena, GCMC simulation was performed demonstrating that the CO₂ molecules are electrostatically trapped via interactions between oxygen on CO₂ and hydrogen on pyridyl moieties of the spacers.