用亚微米级晶种涂层法合成NaA沸石膜及其结构表征

在大孔α-Al2O3陶瓷管载体上,采用亚微米级晶种涂层法在澄清溶液体系中二次生长成膜,制备了NaA沸石膜.采用TEM,SEM和XRD等手段对晶种、陶瓷载体及沸石膜的结构、晶体形貌和成膜情况进行了表征.结果表明,合成晶种的晶粒呈立方体,颗粒小(约150 nm)而均匀,无杂晶,可作为晶种在载体上进行预涂.载体的孔径大而不均匀,表面粗糙不平整,直接成膜则表面仅有较少的沸石晶粒沉积,不能连续成膜.经亚微米级晶种涂层后,载体表面形成了一层均匀、光滑的晶种层(厚度为2～3 μm); 水热晶化成膜后,膜表面晶粒相互交织生长完好,无晶间隙,所得膜致密,连续,规整,清晰,无裂缺.该法是一种制备沸石膜的好方法. A dense and defect-free NaA zeolite membrane with 4 similar to 5 mum thickness on the seeded macroporous a-Al2O3 substrate with submicron seeds was prepared successfully by the secondary growth from clear solution. The substrate, seed layer formed by coating and NaA membrane synthesized by regrowth were characterized by TEM, SEM and XRD. The seed layer with uniform crystal size of 150 nm on the substrate favored the formation of a continuous top-layer zeolite membrane during the growth. The substrate surface could be greatly improved, and a uniform and smooth seed layer with ca 3 mum thickness was formed by seeding. The crystal of the zeolite membrane was cubic and well-intergrown. The substrate, seed layer and membrane were firmly combined together. The synthesized membrane was evaluated by single gas permeation, and showed good molecular sieving property. This method may be useful for the preparation of other type zeolite membranes on macroporous a-Al2O3 substrate.