The micropore volumes and effective pore sizes of two types of silicalite-1 membranes were compared with those of a typical silicalite-1 powder. The silicalite-1 membrane with fewer grain boundaries in the membrane layer showed similar micropore volume and effective pores size to those of the silicalite-1 powder. In contrast, when the silicalite-1 membrane contained many grain boundaries, relatively small micropore volume and effective pore size were observed, suggesting that narrowing and obstruction of the micropore would occur along grain boundaries due to the disconnection of the zeolite pore. The silicalite-1 membrane with fewer grain boundaries exhibited relatively high permeation properties for C6-C8 hydrocarbons. There was an over 50-fold difference in benzene permeance between these two types of membranes. We concluded that it is important to reduce grain boundaries and improve pore-connectivity to develop an effective preparation method for obtaining a highly permeable membrane.
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