Preparation of MFI zeolite membranes in fluoride media and separation performance for ethanol/water mixture

MFI zeolite membranes were synthesized on seeded yttria stabilized zirconia (YSZ) hollow fiber substrates by using ammonium fluoride as mineralizing agent and tetrapropylammonium bromide as template. The as-synthesized membranes were tested for separation of ethanol/water mixture. The influences of n_NH4F/n_SiO2 ratio and synthesis time on separation performance were investigated. High-performance MFI zeolite membrane was synthesized at n_NH4F/n_SiO2=0.8 and synthesis time of 8 h, which showed a permeation flux of 8.2 kg·m^-2·h^-1 and ethanol/water separation factor of 47. The stability of MFI zeolite membranes in ethanol/water mixture was investigated. No Si-OH was detected on the surface of the as-synthesized MFI zeolite membranes, which could avoid decreased membrane separation performance by the reaction between Si-OH and ethanol.