Abstract
Hydrothermal synthesis was applied for preparing an MFI zeolite membrane on a porous stainless support with outer diameter of 7.7 mm, inner diameter of 4.4 mm, length of 12.5 mm, and mean pore diameter of 0.5 µm. To enhance the capability of MFI zeolite formation on the stainless steel support, in this study, a silicalite layer containing no alumina was first synthesized. After that, it was coated with an MFI layer with a Si/Al ratio of 120, where MFI had the same crystal structure with silicalite. The 1-2 times of repeat was required to obtain a gas-tightly coated layer for first and second step. After removing the template by calcining in air at 420°C, the gas permselectivity (H2, N2, Ar, CO2, n-C4H10, iso-C4H10) of MFI/Silicalite double-layered membrane tube was examined in the temperature range of 80 - 440°C. The MFI zeolite membrane was prepared easily to start from silicalite synthesis. Because the crystalline grow probably proceeded more densely, a gas permselectivity based on so-called molecular sieving, i.e., n-/i-C4H10 = 4, could be obtained. For H2, N2, Ar, CO2, the activated diffusion behavior was observed.
