采用含氟体系制备NaY分子筛膜

采用二次生长法,在含氟体系中制备了高渗透气化性能的NaY分子筛膜。比较了含氟体系和无氟体系中NaY分子筛的晶化过程和NaY分子筛膜的渗透气化性能,并对晶化时间和溶胶硅/铝摩尔比(n(SiO2)/n(Al2O3))进行了优化。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱仪(EDX)表征了NaY分子筛膜层晶体结构。结果表明,合成体系中添加NH4F,可有效抑制分子筛膜层中P型分子筛杂晶的形成。含氟体系中合成的NaY分子筛膜比无氟体系合成的NaY分子筛膜具有更高的渗透气化性能。在n(SiO2)/n(Al2O3)=25、晶化时间为6.5h条件下,合成的5根NaY分子筛膜应用在75℃、水/乙醇质量比10/90体系中的平均渗透通量和平均分离因子分别为(5.3±0.3)kg/(m2.h)和63±3。

Preparation of NaY Membrane in Fluorine Containing System

NaY zeolite membrane with high pervaporation performance was synthesized in fluorine containing system by the method of secondary hydrothermal growth. The crystallization of NaY zeolite and the pervaporation performance of NaY membrane synthesized in fluorine containing system were compared with those synthesized in fluorine-free system. Crystallization time and n(SiO₂)/n(Al₂O₃) of the system were also optimized. The as-synthesized NaY zeolite layers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that the addition of NH₄F in synthesis system suppressed the formation of P-type zeolite, which was bedded in the zeolite membrane as the impurity phase. Five NaY zeolite membranes prepared under optimized synthesis conditions of n(SiO₂)/n(Al₂O₃)) of 25, crystallization time of 6.5 h, showed a high average flux of (5.3±0.3) kg/(m²•h) and a good average separation factor of 63±3 for a mixture of water and ethanol with the mass ratio of 10/90 at 75℃, which were higher than those of NaY zeolite membranes prepared in fluorine-free system.