Sustainable synthesis of highly water-selective ZSM-5 membrane by wet gel conversion

High-performance zeolite socony mobil five (ZSM-5) membranes were successfully prepared on a cheap, tubular α-Al2O3 support via a proposed wet gel conversion (WGC), aiming at avoiding the competitive zeolite crystals growth in the solution and ensuring the formation of polycrystalline zeolite layer onto the support surface. A small amount of gel was loaded on seeded tubes via dip-coating and then converted to ZSM-5 membranes via direct crystallization without using any additional synthesis solution for membrane growth. By using this method, the amount of synthetic gel was largely reduced as compared with the traditional hydrothermal synthesis. The effects of crystallization temperature, crystallization duration, and synthetic gel silica source dissolution duration on the morphologies, microstructures, and pervaporation performances of ZSM-5 membranes were investigated. Under optimized synthesis conditions, the as-synthesized ZSM-5 membrane showed high separation performance and stability in isopropanol dehydration. During the 104-h pervaporation test, the permeation flux was stable at 2.96 kg m−2 h−1 with a separation coefficient exceeding 10,000. The synthetic route exhibited excellent reproducibility for the fabrication of highly water-selective ZSM-5 membrane. This work provides a novel, feasible method for the preparation of zeolite membranes with high performance, high atom economy, low cost, and reduced waste solution.