Template-free fabrication of large-scale and highly water-selective monolithic chabazite membranes for water/ethanol separation

The fabrication of large-scale membranes with precisely controlled nanochannel dimensions and exceptional water-steam selectivity remains a formidable challenge. In this study, we have demonstrated the synthesis of high-quality of water-permeable chabazite membranes on 19-channel monolithic supports, which owned a large membrane area of 550 cm² and a high surface-to-volume ratio of 311 m²/m³. The area of pilot-scale monolithic membrane was 50 % higher than the commercialized tubular membrane. Intergrown chabazite membranes were prepared on the large-area monolithic supports by optimizing synthesis parameters such as seeding and gel composition. The best membrane on large-area support prepared under optimized conditions exhibited water flux, water permeance and water/ethanol selectivity of 1.6 kg/(m² h), 3.4 × 10⁻⁷ mol/(m² s Pa) and 22,000 at 393 K by vapor permeation (VP), respectively. The effects of temperature and feed composition on separation performance were comprehensively investigated by VP and PV. Furthermore, the membranes displayed remarkable hydrothermal stability even in a high-water-content ethanol aqueous solution with 50 wt% water in PV model at 358 K and in VP model at 393 K for 6 days. The robust monolithic chabazite membranes, characterized by high surface-to-volume ratio, strong mechanical integrity, large area, and high separation performance, show the great potentials for water/organic separations.