Investigation of the Structure–Activity Relationship Between Functionalized UiO‐66 and Separation Performance for CO ₂ /CH ₄ Based on GCMC Simulation and Experiment

ABSTRACT Natural gas (NG) is a typical low‐carbon energy source. It is necessary to remove CO 2 to enhance the NG calorific value and prevent transportation pipeline corrosion. Functionalized UiO‐66 is widely used in gas separation, whereas there is a trade‐off between adsorption capacity and separation selectivity in this process. Therefore, this study combines experiment and GCMC simulation, validating the accuracy of simulation model by comparing the CO 2 and CH 4 adsorption capacity on UiO‐66 and UiO‐66‐NH 2 . Afterwards, a series of functionalized UiO‐66‐X (X = H, NH 2 , NO 2 , Br, OH, SH, Me, OMe, PDC) were designed by directly substituting the functional groups on ligands, and their corresponding pore architecture effect on CO 2 /CH 4 separation performances were also analyzed. Results showed that the separating effect is influenced by multiple factors (including pore volume, gas affinity, and fluid–solid interactions), leading to variations in adsorption capacity, isosteric heat of adsorption, adsorption density distribution, and CO 2 /CH 4 selectivity. At low pressure, the adsorption capacity is primarily influenced by fluid–solid interactions, whereas affected by surface area and pore volume at high pressure. Thus, the functionalized UiO‐66 exhibited customized pore size/shape and chemistry, creating a synergistic effect for CO 2 /CH 4 separation, where their structure–activity relationships also provided theoretical guidance for further research.