Preparation and Permeation Properties of NaA Zeolite Membrane by Vapor Phase Transformation Method

Abstract

The NaA zeolite membranes with high permeance were synthesized by seeding and secondary growth both using vapor phase transformation method (VPT). The SEM image of seed layer on substrate indicated that the size of seeds was about 60nm. The XRD patterns showed that the formation of NaA zeolite membrane was after vapor phase transformation of 12h, and the pure NaA zeolite crystals formed on substrate. The SEM images showed that the NaA zeolite membrane consisted of compact polycrystalline crystals with an average size of ca. 2µm. The permeation results showed that the H2 permeance s of NaA membranes attained at the level of 10-6 mol/Pa·m2·s, and the maximum permselectivities of the H2/N2, H2/CO and H2/C3H8 were 4.15,4.78 and 10.1, respectively, which were higher than those of the corresponding Knudsen diffusion selectivities. However, the permeation of C3H8 suggested that there existed unwanted intercrystalline pores or defects in the membranes.