Microwave-Assisted Synthesis and Permeation Performance of NaA Zeolite Membrane by Secondary Growth Method

Abstract

The highly intergrown NaA zeolite membranes on seeded α-Al2O3substrate were synthesized by microwave heating method. The preparation of seeds with the size of ca.120nm employed the vapor phase transport method (VPT). The XRD patterns indicated that the pure NaA zeolite membranes formed on the seeded α-Al2O3substrate for varied synthesis times. However, the peak intensity of NaA zeolite membrane with synthesis time of 50min obviously decreased, suggesting that the NaA membrane could take place the dissolution at that time. The SEM images indicated that the NaA zeolite membranes with synthesis time of 15-30min had a good integrity and consisted of highly intergrown zeolite crystals, but the NaA membrane with synthesis time of 50min appeared some large defects, further verifying the result of XRD pattern. The gas permeability showed that the maximum of H2/N2and H2/C3H8permselectivities attained 4.23 and 8.24, respectively, higher than those of the corresponding Knudsen diffusion. These results suggested that the diffusion of gases, at least in part, are affected by the pore size of zeolite and the function of molecular sieving can be embodied on the synthesized membrane.