Scalable Room-Temperature Synthesis of a Hydrogen-Sieving Zeolitic Membrane on a Polymeric Support

Thescalable synthesis of high-temperature H-2-sieving membranesfor energy-efficient carbon capture can potentiallyenable the implementation of precombustion carbon capture at a rapidpace. Synthesis of H-2-sieving membranes for high-temperatureapplications is highly desired for improving the energy efficiencyof H-2 production from steam reforming and developing alow-cost solution for precombustion carbon capture. Zeolite-basedmembranes are ideal for this because they possess excellent hydrothermalstability. However, current methods to synthesize H-2-sievingzeolite membranes rely on hydrothermal synthesis on expensive ceramicsupports followed by postsynthetic functionalization to shrink theeffective pore size. The scalable synthesis approach on a low-costpolymeric support implementable at room temperature is highly desiredto advance applications based on H-2-sieving membranes.Herein, we report the room-temperature fabrication of H-2-sieving zeolitic membranes by simply assembling sodalite precursor,i.e., RUB-15 nanosheets, on a porous polybenzimidazole support. Thepresence of adsorbed surfactants on the nanosheets led to an entropicallydriven ordering of the nanosheets witnessed by a sharp (200) d-spacing peak by X-ray diffraction. The intersheet gapwas successfully eliminated by the ion exchange of cationic surfactantsby a diluted acetic acid solution. The resulting zeolitic films showattractive H-2/CO2 and H-2/CH4 separation performances at elevated temperatures. The fabricationof H-2-sieving zeolitic membranes without resorting to hydrothermalsynthesis or high-temperature activation is expected to push the effortsto scale up zeolite membranes for application in gas separation andmembrane reactors.