High performance dehydration of ethyl acetate/water mixture by pervaporation using NaA zeolite membrane synthesized by vacuum seeding method

High quality NaA zeolite membranes were prepared by vacuum assisted secondary growth. At the first stage in which NaA powder was synthesized, increasing the aging time led to formation of impure and smaller crystals. However, at the aging time of 48 h, pure NaA zeolite particles with average particle size of 1.5 μm were obtained. In the second stage, the outer surface of porous α-Al2O3 tubular supports were seeded by vacuum method using 1.5 μm NaA particles. The most stable and uniform seeded layer was obtained at seeding time and suspension concentration of 90 s and 5 g L−1, respectively. Then, 6 h of secondary growth of the zeolite layer on the seeded surface was carried out at 373 K three times. The XRD and SEM results showed the formation of a uniform and dense layer of pure NaA zeolite with an average thickness of 45 μm. Dehydration experiments were conducted on ethyl acetate/water mixtures with 2 wt% water content. The average total fluxes were 0.147, 0.208, and 0.315 kg m−2 h−1 at 303, 313, and 323 K, respectively. The separation factor was 163,000. This parameter did not change with temperature and it was due to very close activation energies of ethyl acetate and water.

► High performance NaA zeolite was synthesized for dehydration of ethyl acetate. ► Increasing aging time from 48 to 72 h led to formation of impure phases. ► Seeding time and suspension concentration had significant effects on seeding layer. ► Very high separation factor of 163,000 was obtained. ► Separation factor did not change with temperature.