Facile synthesis of zeolite FAU molecular sieve membranes on bio-adhesive polydopamine modified Al2O3 tubes

A seeding free synthesis strategy was developed for the preparation of dense and phase pure zeolite FAU membranes through mussel-inspired polydopamine (PDA) modification of porous Al2O3 tubes. Zeolite FAU nutrients can be attracted and bound to the support surface via the formation of strong non-covalent and covalent chemical bonds, thus promoting the nucleation and growth of uniform, well-intergrown and phase-pure zeolite FAU membranes. The SEM and XRD characterizations demonstrate that a relative thin but dense and pure-phase zeolite FAU membrane with a thickness of about 2.3 mu m can be obtained on the PDA-modified Al2O3 tube after crystallization at 75 degrees C for 24 h, and no visible cracks, pinholes or other detects are observed on the membrane layer. The zeolite FAU membrane prepared at 75 degrees C for 2411 was evaluated in single gas permeation and mixed gas separation. For binary mixtures at 50 degrees C and 1 bar, the mixture separation factors of H-2/CH4 and H-2/C3H8 are 9.9 and 127.7, respectively, which are much higher than the corresponding Knudsen coefficients. And relative high H-2 permeance of about 1.9 x 10(-7) mol m(-2) s(-1) Pa-1 can be obtained through the FAU membrane due to the thin layer and the relative wide pore size of 0.74 nm, demonstrating a viable direction for promising application of FAU membranes in hydrogen purification and separation. (C) 2015 Elsevier B.V. All rights reserved