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

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 Al2O3 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 mu m can be formed on the alpha-Al2O3 support, and no cracks, pinholes or other defects are visible. The LTA zeolite membrane displays good molecular sieving performance. For binary mixtures at 20 degrees C, the separation factors of H-2/CH4, H-2/N-2, H-2/O-2 and H-2/CO2 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 x 10(-7) mol m(-2) s(-1) Pa-1 can be obtained. (c) 2009 Elsevier B.V. All rights reserved.