High performance NaA zeolite membrane for hydrogen separation synthesized on an organic-functionalized α-Al2O3 ceramic hollow fiber surface

Abstract

Positively charged organic-functionalized α- Al2O3 ceramic hollow fiber was obtained by dip-coating the substrate with a 3-aminopropyl-(diethoxy)methylsilane (ADMS) solution. Negatively charged NaA zeolite particles were deposited on the substrate surface and used as seed for further secondary growth by the electrostatic adsorption of a positively charged organic-functionalized substrate and NaA zeolite particles. The NaA zeolite membrane was synthesized on a porous α-Al2O3 ceramic hollow fiber support by the microwave heating-secondary growth method. The as-synthesized NaA zeolite membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential, and gas permeation tests. The differences in morphology, structure, and gas permeability between the NaA zeolite and the ADMS-modified substrate supported NaA zeolite membrane were determined. XRD results show that only NaA zeolite is present on the support. The zeta potential results indicate that opposite charges exist between the NaA zeolite seed or precursor and the organic-functionalized substrate surface, which confirms the electrostatic adsorption between them. SEM images show that a smooth and dense membrane (5 μm thick) is obtained and the particles are twinborn by good intergrowth on the ADMS-modified substrate supported NaA zeolite membrane surface. Gas permeation tests with H2, O2, N2, and C3H8 at different temperatures show that the permeability of H2 on the ADMS-modified substrate supported NaA zeolite membrane at 35 °C is 3.6×10-7 mol·m-2·s-1·Pa-1, which is lower than that (4.0×10-7 mol·m-2·s-1·Pa-1) of the NaA zeolite membrane. The ideal permselectivity of H2/C3H8 is 11.25, which is far higher than that (5.06) of the NaA zeolite membrane. © Editorial office of Acta Physico-Chimica Sinica.