Covalent organic frameworks for gas storage and separation

Gas storage and separation are critical for industrial, environmental, and energy sustainability, yet conventional methods like cryogenic distillation and compression suffer from high energy consumption, cost, and infrastructural complexity. Physical adsorption using porous materials, operating without gas-phase transitions, presents a promising alternative due to its low energy requirements and ease of operation. Covalent organic frameworks (COFs), a new class of crystalline porous materials synthesized through covalent bonding, have demonstrated significant potential as adsorbents due to their structural regularity, excellent stability, high surface areas, low density, and tunable pore properties, including the pore size, shape, and environment. These attributes facilitate efficient gas storage and separation. This comprehensive review summarizes the latest advancements in gas storage and separation using COF materials. Adsorption-based methods will be emphasized, with supplementary coverage of membrane-based technology. Based on the properties of gases, the main part will be divided into the following parts: hydrogen storage, methane storage, hydrocarbon separation, CO₂ capture, SO₂ capture, SF₆ capture, H₂/D₂ separation, NH₃ separation, and CH₄/N₂ and O₂/N₂ separations. In addition, the underlying mechanisms of separation, the innovation in COF structural design, and the strategies (e.g., bottom-up synthesis, post-synthetic modification, and interpenetration regulation) employed to enhance storage or separation performance will be analyzed. Finally, this work will outline the key challenges in translating COF materials from laboratory research to industrial applications, while highlighting the prospects of future developments in COF materials for gas storage and separation.