Hydrophobic naphthalene‐based porous organic polymers achieving CH 4 / N 2 adsorption separation under humid conditions

Abstract The efficient adsorption separation of CH 4 /N 2 from low‐concentration methane mixtures is a crucial prerequisite for its resource utilization. However, the separation performance of the common adsorbents would be severely weakened under humid conditions. Herein, a series of hydrophobic and porous organic polymers derived from naphthalene (PNs) were synthesized via the anhydrous AlCl 3 ‐catalyzed Friedel‐Crafts alkylation between naphthalene and dichloromethane, demonstrating high performance in CH 4 /N 2 separation with exceptional tolerance to humid conditions. The pore size of the PNs could be tailored by varying the amount of AlCl 3 during synthesis, enabling precise tuning of the micropore size from 0.58 nm to 0.78 nm. With a robust framework of methylene bridges and aromatic rings, the resulting PNs exhibit superior hydrophobicity. Breakthrough experiments under 40% and 75% relative humidity demonstrate that the PNs retain separation performance comparable to dry conditions. These findings underscore the potential of PNs for enriching CH 4 from low‐concentration methane mixtures under humid conditions.