Temperature and Pressure Effects on Adsorption Enthalpies and Selectivities of CO 2 , CH 4 , and N 2 in ZIF‐412

Zeolitic imidazolate frameworks (ZIFs) are promising adsorbents due to their tunable pore structures and surface‐active sites for selective gas adsorption. This study presents the synthesis and characterization of a large‐cage polyhedral zeolitic imidazolate framework (ZIF‐412) and evaluates its adsorption capacities for CO 2 , N 2 , and CH 4 at different temperatures and pressures. ZIF‐412 exhibits a surface area of 917.76 m 2 /g, with 88% microporosity. The adsorption–desorption and cyclic adsorption tests for CO 2 , N 2 , and CH 4 were conducted at 303 K up to 3000 kPa, demonstrating excellent reversibility and stability. At 273 K and 3000 kPa, the maximum uptakes were 8.1, 2.8, and 4.7 mmol/g, respectively, whereas at 323 K, the corresponding values were 6.0, 1.7, and 3.3 mmol/g for CO 2 , N 2 , and CH 4 , respectively. The gas adsorption enthalpies derived using the Freundlich–Langmuir, virial, and Clausius–Clapeyron models were about −24, −14, and −17 kJ/mol for CO 2 , N 2 , and CH 4 , respectively, indicating an exothermic physisorption process influenced by pore confinement and framework–gas interactions. Additionally, ZIF‐412 exhibited high CO 2 /N 2 selectivity above 20, compared with 3 for CO 2 /CH 4 below 20 kPa at 273–313 K. The trade‐off between adsorption capacity and selectivity highlights its potential for low‐energy CO 2 capture applications.