Reversible Trace‐Water‐Buffering Frameworks for Efficient Humid Methane Purification

Trace water is usually fatal to gas separation process because the adsorption sites of adsorbents can be readily devitalized under humid conditions. Here, we develop trace-water-buffering porous materials with reversible structural transformation triggered by water adsorption/desorption, achieving exceptional methane purification under humid conditions. Despite the different structures, both the hydrated and dehydrated materials show high adsorption capacities for bulky C₃H₈ and intermediate-sized C₂H₆ molecules but low CH₄ uptake. Based on these unique properties, the dehydrated material achieves efficient separation of ternary CH₄/C₂H₆/C₃H₈ mixtures even under 100% relative humidity, delivering high-purity CH₄ (>99.99%) with a remarkable yield of 7.2 mmol·g^-1. This work sheds light on the designed synthesis of a new generation of microporous materials with reversible water-buffering performance for gas purification under practically humid conditions.