二次生长法制备高分离性能的PHI分子筛膜

通过二次生长法在α-Al2O3支撑体表面合成了PHI分子筛膜,考察了晶种合成方式、二次生长合成温度及时间对形成PHI分子筛膜的影响.采用X射线衍射(XRD)、扫描电子显微镜(SEM)对合成膜进行表征.结果表明:载体表面合成出了PHI分子筛;二次生长法合成出的PHI分子筛膜连续、致密,膜厚约为20 μm.利用渗透汽化技术对甲醇、乙醇、异丙醇和叔丁醇等不同分子尺寸的醇/水体系进行分离性能的研究,同时考察原料液中水含量对所制备的PHI分子筛膜的分离性能的影响.结果表明:PHI分子筛膜对几种醇水体系都具有良好的分离效果,随着水含量的增加,水的渗透通量呈增大趋势,乙醇和甲醇的理想分离因子有所降低,异丙醇和叔丁醇的理想分离因子增大.

Preparation of PHI Zeolite Membrane with High Separation Performance by the Secondary Growth Method

PHI zeolite membrane was prepared by the secondary growth method on the surface of a porous α-Al₂O₃ disk support. The effects of the zeolite seed preparation method, secondary growth time, and temperature on membrane synthesis were investigated. The as-synthesized PHI zeolite membranes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results show that PHI zeolite emerges on the support. The SEM results show that the support surface is fully covered by uniform and compact PHI zeolite membrane synthesized by the secondary growth method and the thicknesses of the membrane layer was found to be about 20 μm. The as-synthesized PHI zeolite membranes were used for dehydration of methanol (MeOH), ethanol (EtOH), isopropanol (IPA), and tert-butanol (TBA) solutions with different kinetic diameters. The influence of feed concentration on the separation performance was investigated by pervaporation tests. The results show that the PHI membranes exhibited excellent performance of the dehydration of alcohol/water mixtures. It was found that the flux and the separation factors of isopropanol and tert-butanol increased with the increment of the water amount in the feed and the separation factors of methanol and ethanol decreased slightly.