Zeolite membranes exhibit considerable potential for gas separation; however, two critical challenges (low permeation flux and scaling-up fabrication) continue to hinder their practical implementation. Here, we propose an embryonic zeolite-mediated suture (EZMS) strategy to synthesize large-area zeolite membranes with stable gas separation performance. The membrane thickness is equivalent to that of the initial seed layer—a feature validated across three distinct zeolite frameworks (STT, CHA, and MFI). For high-silica CHA (also known as SSZ-13) zeolite membranes, the EZMS strategy enables a 5-fold thickness reduction, yielding a CO₂ permeance of 1.02 × 10^-6mol·m^-2·s^-1·Pa^-1 (3000 GPU) and a CO₂/CH₄ selectivity of 158 at 0.2 MPa. Scalability is validated by the successful synthesis of SSZ-13 zeolite membrane bundles with an individual area of 0.5 m² (40 cm in length). The membranes exhibited excellent high-pressure resistance (>4 MPa) and long-term stability (>220 d) for humid CO₂/CH₄ separation, representing a high-performance benchmark for biogas upgrading. The reliable synthesis protocol and improved performance highlight the industrial application potential of zeolite membranes.

High-silica CHA zeolite membranes are highly desired for natural gas upgrading because of their separation performance in combination with superior mechanical and chemical stability. However, the narrow synthesis condition range significantly constrains scale-up preparation. Herein, we propose a facile interzeolite conversion approach using the FAU zeolite to prepare SSZ-13 zeolite seeds, featuring a shorter induction and a longer crystallization period of the membrane synthesis on hollow fiber substrates. The membrane thickness was constant at ~3 μm over a wide span of synthesis time (24-96 h), while the selectivity (separation efficiency) was easily improved by extending the synthesis time without compromising permeance (throughput). At 0.2 MPa feed pressure and 303 K, the membranes showed an average CO2 permeance of (5.2±0.5)×10−7 mol m−2 s−1 Pa−1 (1530 GPU), with an average CO2/CH4 mixture selectivity of 143±7. Minimal defects ensure a high selectivity of 126 with a CO2 permeation flux of 0.4 mol m−2 s−1 at 6.1 MPa feed pressure, far surpassing requirements for industrial applications. The feasibility for successful scale-up of our approach was further demonstrated by the batch synthesis of 40 cm-long hollow fiber SSZ-13 zeolite membranes exhibiting CO2/CH4 mixture selectivity up to 400 (0.2 MPa feed pressure and 303 K) without using sweep gas.