Fluoride-mediated synthesis of high-flux chabazite membranes for pervaporation of ethanol using reusable macroporous stainless steel tubes

Pure and intergrown chabazite layers were synthesized on symmetric stainless steel supports using fluoride route. The location of fluoride specie in membrane crystals and the effect of fluoride precursor on the crystallization of supported chabazite layers were demonstrated. Membrane morphologies and qualities were strongly influenced by fluoride concentration, synthesis time, aging time and gel composition. The best membrane synthesized in fluoride media displayed a high flux of 6.0 kg/(m² h) (water permeance of 16,000 GPU) and separation factor of 2000 (selectivity of 2300) for a 90 wt% ethanol aqueous solution at 348 K, whose flux was ~60% higher than our pervious fluoride-free membrane. The stainless steel substrates can be repeatedly utilized for the growth of chabazite membrane with high performance after a simple clean process, which reduces membrane cost to a large extent. Fluoride-mediated synthesis of chabazite membrane was reproducible and the resulted membranes showed high hydrothermal, long-term test and acid stabilities.