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

Abstract

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 SiO 2 /Al 2 O 3 and H 2 O/SiO 2 , 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 1SiO 2 :0.015Al 2 O 3 :0.41 (Na 2 O+K 2 O):30H 2 O, 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/(m 2 ·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. 以自制微米级分子筛为晶种, 在清液体系中成功合成出高性能的 T 型分子筛膜, 考察了硅铝比、水硅比、碱度及合成温度与时间等条件对膜的生长和渗透汽化性能的影响. 结果表明, 在摩尔组成为 1SiO 2 :0.015Al 2 O 3 :0.41 (Na 2 O+K 2 O):30H 2 O 的清液体系中, 于 423 K 晶化 6 h 的条件下可较快地形成一层厚度为 5 μm 的连续致密纯相 T 型分子筛膜, 较大缩短了膜合成时间且提高了膜致密性. 在优化条件下所合成的膜具有优良的分离性能和高重复性. 348 K 时, 在 10 wt% 水-90 wt% 异丙醇混合物体系中膜的渗透通量和分离因子分别高达 4.20 kg/(m 2 ·h) 和 7800. Highly reproducible zeolite T membranes were hydrothermally synthesized from clear solutions. Synthesis parameters, especially alkalinity, strongly affect the membrane growth and pervaporation performance.