Seeding-free synthesis of FAU-type membrane with dry gel modified α-alumina support

Dense and pure zeolite FAU membrane was obtained with dry gel modified α-alumina support. Before aging-microwave (AM) process, α-alumina support was covered with dry homogenous gel layer. Compared to membrane synthesized with the single AM process, zeolite FAU membrane prepared with dry gel modified AM method displayed high pervaporation performance with flux of 2.19 kg/m2·h (average value) and water permeation of 99.5% (average value) for the mixture of water/ethanol (10/90) at 60 °C. Characterizations revealed that high local alkalinity over the dry gel layer could promote the nucleation and the growth of zeolite FAU membrane. However, excessive content of dry gel caused the formation of Sodalite (SOD) impurities. Furthermore, the synthesis conditions of zeolite FAU membrane with dry gel modified AM method were optimized systematically. The synthesis of high-performance membrane with the optimal conditions showed good reproducibility and high efficiency, implying that dry gel modified AM method was a promising method to synthesize pure zeolite FAU membrane. Pure and dense zeolite FAU membrane with high pervaporation performance for water ethanol mixture was obtained with a green and facile dry gel modified AM method.fx1. [Display omitted] •Pure and dense FAU membranes were synthesized with dry gel modified α-Al2O3 support.•The coating gel on α-Al2O3 support is same as the synthesis solution.•Dry gel modification promotes nucleation and growth of FAU membranes.•The obtained FAU membranes display high pervaporation performances of dehydration.