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

Abstract

Synthesis of H2-sieving membranes for high-temperature applications is highly desired for improving the energy efficiency of H2 production from steam reforming and developing a low-cost solution for precombustion carbon capture. Zeolite-based membranes are ideal for this because they possess excellent hydrothermal stability. However, current methods to synthesize H2-sieving zeolite membranes rely on hydrothermal synthesis on expensive ceramic supports followed by postsynthetic functionalization to shrink the effective pore size. The scalable synthesis approach on a low-cost polymeric support implementable at room temperature is highly desired to advance applications based on H2-sieving membranes. Herein, we report the room-temperature fabrication of H2-sieving zeolitic membranes by simply assembling sodalite precursor, i.e., RUB-15 nanosheets, on a porous polybenzimidazole support. The presence of adsorbed surfactants on the nanosheets led to an entropically driven ordering of the nanosheets witnessed by a sharp (200) d-spacing peak by X-ray diffraction. The intersheet gap was successfully eliminated by the ion exchange of cationic surfactants by a diluted acetic acid solution. The resulting zeolitic films show attractive H2/CO2 and H2/CH4 separation performances at elevated temperatures. The fabrication of H2-sieving zeolitic membranes without resorting to hydrothermal synthesis or high-temperature activation is expected to push the efforts to scale up zeolite membranes for application in gas separation and membrane reactors.