Synthesis and pervaporation performance of highly reproducible zeolite T membranes from clear solutions

Zeolite T membranes with very good permeation performance were successfully synthesized on porous mullite supports by the secondary growth method with homemade microsized seeds from clear solutions. The influence of synthesis parameters such as the molar ratios of SiO₂/Al₂O₃ and H₂O/SiO₂, alkalinity, synthesis temperature, and crystallization time on membrane growth and permeation performance was investigated systematically. It is found that these parameters strongly affect the zeolite T growth and pervaporation performance of the membranes. Under the optimized synthesis conditions of 1SiO₂:0.015Al₂O₃: 0.41(Na₂O+K₂O):30H₂O, the crystallization time was shortened to 6 h at 423 K and a continuous and dense T-type zeolite layer as thin as 5 μm formed on the surface of the support. It significantly improved the membrane density and permselective properties. A permeation flux and separation factor of 4.20 kg/(m²·h) and 7800, respectively, were obtained with the as-synthesized membrane for 10 wt% water-90 wt% i-propanol mixtures at 348 K. It also exhibited a very good pervaporation performance for water/ethanol mixtures separation. This high quality zeolite T membrane could be reproducibly prepared.