Assembly of Sponge‐Like Metal–Organic Framework Architecture on an Ultrathin Polymer Membrane for Various H ₂ /Hydrocarbon Separations

Abstract Emissions from the petrochemical industry often contain by‐product hydrogen alongside various hydrocarbons, leading to both resource wastage and increased air pollution. The separation of H 2 from these hydrocarbons is thus of considerable economic and environmental importance. Conventional polymer membranes face inherent trade‐offs between gas permeability and selectivity. To overcome this limitation, this study introduces a strategy to assemble metal–organic framework (MOF) nanoparticles into a sponge‐like architecture on the surface of an ultrathin rubbery polysiloxane membrane, achieved by synergistically harnessing spin‐coating‐induced centrifugal forces and polymer–MOF chemical pinning forces. The resulting intricate sponge‐like structure greatly promotes repeated adsorption–desorption cycles for the more condensable hydrocarbons, thereby markedly slowing their permeation through the membrane. The composite membrane achieves H 2 /CH 4 , H 2 /C 2 H 6 , and H 2 /C 3 H 8 separation factors of 136, 1370, and 1610, respectively, while maintaining H 2 permeances of 439 to 473 GPU. The membrane's effectiveness is further demonstrated for hydrogen separation from a simulated hydrocarbon‐rich industrial tail gas: H 2 is enriched from 10% to 83% in the permeate. In doing so, the membrane not only efficiently recovers hydrogen but also reduce the combined emissions of six representative C 1 –C 4 hydrocarbons by 78%. This sponge‐like MOF‐polymer composite introduces a new paradigm for advanced H 2 /hydrocarbon separation membranes.