Ultrahigh flux zeolite membranes for hydrogen separation

MFI zeolite membranes with high gas permselectivities were successfully prepared on novel porous silica substrates. Procedures for coating of MFI seed crystals were important due to the -potential between the substrates and the seed crystals. Dense MFI membranes were obtained from the seed slurry of pH 2, because the both isoelectric pH of the silica substrates and the MFI seeds are almost the same at 2. N₂ permeance was 3.7 x 10^-6 mol m^-2 s^-1 Pa^-1 with high N₂/SF₆ permeance ratio of 328 through the membrane prepared on the thin silica substrate of 1.3 mm. Molecular size of SF₆ is smaller than that of toluene indicating that this membrane can be applied for the decomposition reaction of organic hydrides such as methyl-cyclohexane to produce hydrogen.