Preparation of MFI Membrane on Mesoporous-Layer-Modified Macroporous Al2O3 Substrate by Secondary Growth Method and its Permeation Property

The compact MFI membrane supported on a mesoporous-layer-modified macroporous Al2O3 substrate has been prepared by the secondary growth method. SEM images indicate that the MFI membranes with the thickness of ca. 15 μm consist of highly intergrown crystals with remarkable integrity. The H2 permeance of MFI membranes on mesoporous/macroporous substrate is 8-18 times larger than that on the macroporous substrate, and further the permselectivity of H2/C3H8 maintains at the level of 20, which is 4 times higher than that of the corresponding Knudsen diffusion. More importantly, the real selectivity of the mixture of H2/C3H8 on these membranes is 2-4 times higher than that of the corresponding Knudsen diffusion. The method is attractive for the practical application.