Highly Oriented Thin Membrane Fabrication with Hierarchically Porous Zeolite Seed

Abstract

Nanosized zeolite is widely used as seed for high quality zeolite membranes fabrication, while its complicated synthesis routine limits large-scale productions. In this work, a non-nanosized cubic hierarchically porous TS-1 zeolite (HTS-1), obtained by basic hydrothermal treatment of conventional ellipsoid solid TS-1, is used as seed to prepare highly oriented thin membranes. A capillary condensation phenomenon resulting from the unique hierarchically porous structure benefits gel attachment. Moreover, abundant ledges, kinks, and terraces on the HTS-1 surface promote epitaxial growth of the membrane. In contrast, the solid TS-1 seed induces intergrowth dominantly, which results in a thick TS-1 membrane. The HTS-1 membrane demonstrates superior CO2/N2 separation properties compared to the TS-1 one. It associates with thin oriented membrane morphology, leading to exposure of a high Miller index surface and less diffuse distance and tortuosity. The results suggest beneficial effects of a hierarchically porou...