A high reproducible fabrication method for industrial production of high flux NaA zeolite membrane

A high reproducible fabrication method for high-flux NaA zeolite membrane has been developed for industrial mass production. The synthesized NaA membranes exhibited higher water flux (5.6 kg m−2 h−1) by pervaporation (PV) experiments in a mixture of water (10 wt.%)/ethanol (90 wt.%) at 348 K compared with those of previous reported for the comparable water/alcohol separation factors, α (103–104). Vapor permeation (VP) experiments on saturated vapor with the above mixture up to 418 K and 930 kPa showed so high performance of flux of 31 kg m−2 h−1 with α > 104 that can be applied practically to such a hybrid system of distillation-vapor permeation. High reproducibility in the developed fabrication method for membranes was confirmed by permeation tests. Pore size distribution estimated by permporosimetry showed that an average pore size was 0.7 nm in Kelvin diameter and half of the gas flow permeate through nonzeolitic pores. The thickness of effective layer in the membrane was determined by a focused ion beam (FIB) preparation method to be ca. 4 μm that was thinner than those of previous studies. It could be suggested that the higher flux is attributed mainly to lower transporting resistance by the thin layer and existence of nonzeolitic pores in the membranes.