Preparation and separation properties of LTA membranes by using 3-aminopropyltriethoxysilane as covalent linker

Abstract

Abstract A novel synthesis strategy was developed for the seeding-free preparation of dense LTA zeolite membranes by using 3-aminopropyltriethoxysilane as covalent linker between zeolite membrane and porous Al 2 O 3 support. In a first step, the ethoxy groups of the 3-aminopropyltriethoxysilane react with surface hydroxy groups of the support. In a second step, the 3-aminopropylsilyl groups react with silanols of the zeolite crystals, leading to a “bridge” between the growing LTA zeolite membrane and the support being built to anchor the LTA zeolite layer onto the support. The SEM image and XRD indicate that a dense and pure LTA zeolite membrane with a thickness of about 3.5 μm can be formed on the α-Al 2 O 3 support, and no cracks, pinholes or other defects are visible. The LTA zeolite membrane displays good molecular sieving performance. For binary mixtures at 20 °C, the separation factors of H 2 /CH 4 , H 2 /N 2 , H 2 /O 2 and H 2 /CO 2 are 3.6, 4.2, 4.4 and 5.5, respectively, which are higher than the corresponding value of Knudsen diffusion. Moreover, relative high H 2 permeances of about 3.0 × 10 −7 mol m −2 s −1 Pa −1 can be obtained.