Grafting of functional organic ligand on zeolite Y for efficient CH4/ N2 separation

The unique shape selectivity of zeolite is widely used in gas separation, but the preparation of adsorbents for the efficient separation of CH 4 /N 2 is technically challenging due to their similar physical properties. Herein, we performed a two-step modification of commercial zeolite Y by ion exchange (Zn 2 + ) and ligand (almIM) grafting, and successfully introduced metal complexes into the pores of zeolite NaY. The suitable pore size (0.4 nm) and the presence of functional groups made the adsorbents more efficient for CH 4 /N 2 separation. At 298 K and 1 bar, the CH 4 /N 2 selectivity of ZnY-almIM reached to 4.52, which was significantly higher than that of the pristine zeolite NaY (1.52). DFT simulations confirmed that the introduction of ligands enhanced the affinity between the zeolite framework and CH 4 . Breakthrough experiments have demonstrated that ZnY-almIM exhibits excellent CH 4 /N 2 separation performance, and more importantly, the two-bed six-step pressure swing adsorption (PSA) simulations further indicated that the pristine 50 % methane could be enriched to 90 % with a recovery of 87 %.