两步变温水热合成制备纯硅分子筛膜及其渗透性能

采用两步变温水热法在多孔不锈钢载体管上合成了Silicalite-1沸石膜，对合成的Silicalite-1膜进行了X射线衍射和扫描电镜及单成分气体渗透表征，并将其应用于渗透脱除水中乙醇，考察了晶化温度、合成液组成及合成次数对渗透性能的影响. 结果表明，用两步变温合成法可得到高性能的纯硅沸石膜，水/硅(摩尔比)为80且第二步晶化温度为165℃的条件下，只需经一次合成，可获得对乙醇水溶液具有高分离性能的膜，在60℃、乙醇浓度为4.8%(w)时，膜的通量为1.25 kg/(m2×h)，分离系数为36.2，但经再次合成后，通量和分离系数均劣化. 水/硅(摩尔比)为225且第二步晶化温度为150℃条件下，经过再次合成，通量和分离系数均得到大大提高，在60℃和乙醇浓度为4.52%(w)时，通量和分离系数分别高达2.8 kg/(m2×h)和34.3，在如此高的分离系数下该通量达到了国内外报道的最高值.

Preparation and Pervaporation Performance of Silicalite-1 Zeolite Membrane with a Two-stage Temperature-varied Hydrothermal Technique

A two-stage temperature-varied hydrothermal technique was adopted to synthesize Silicalite-1 zeolite membrane supported on the porous stainless steel tube for pervaporation separation of ethanol from water. The effects of crystallization temperature and synthesis time on the pervaporation performance of the membrane were investigated with the synthesis solution composition specified in this work. The prepared membrane was characterized by XRD, SEM and single gas permeation tests. The result showed that a membrane with a flux of 1.25 kg/(m2×h) and separation factor of 36.2 at the ethanol content of 4.8%(w) and 60℃ could be obtained only through one time synthesis when the H2O/Si ratio in molar was 80 and the second stage crystallization temperature was high at 165℃. Instead, a flux of 2.8 kg/(m2×h) same as the highest one reported in the literature with separation factor of 34.3 at the same separation condition was obtained using the Silicalite-1 membrane through twice synthesis when H2O/Si ratio was 225 and the second stage crystallization temperature low at 150℃.