A Sacrificial Seed Layer Strategy for Hierarchical MFI Zeolite Membranes With Enhanced Butane Isomer Separation Performance

Abstract

ABSTRACT Zeolite membranes hold significant promise for industrially relevant gas separations; however, balancing high permeance and selectivity remains a persistent challenge. Although thinning the selective layer improves permeance, achieving precise fabrication remains a major bottleneck. Herein, we demonstrate a sacrificial seed layer strategy enabling the fabrication of hierarchical MFI zeolite membranes (HMFI) on commercial α‐Al 2 O 3 tubes. Through precise modulation of synergistic ionic interactions within the synthetic gel and the nutrient supply rate during crystallization, the seed layer functions as both a porogen to generate a macroporous sublayer and a “fertilizer” to promote surface gel crystallization, forming a dense top layer. The resulting HMFI membrane delivers more than a fourfold enhancement in the ideal selectivity of n ‐butane and isobutane ( n‐ / i‐ butane), accompanied by a 37% rise in n ‐butane permeance compared with conventional MFI membranes. Moreover, with a 10/90 n‐ / i‐ butane mixture, it exhibits an excellent separation factor of 158, along with a high n ‐butane permeance (188 × 10 −9  mol m −2 s −1 Pa −1 ), representing the highest performance for reported membranes on tubular supports. The strategy not only enables a novel route to high‐performance membranes, but also enriches the conceptual framework of the conventional secondary growth protocol, offering new avenues for microstructural engineering.