Synthesis and characterization of NaA zeolite powder/film deposited on alumina beads by dip-coating method

摘要

Linde Type A (LTA) zeolites have been synthesized in the current study by simple sol-gel technique. The crystal growth has been controlled by varying the hydrogel synthesis time and annealing temperature. The resulting products obtained at various crystallization times and temperatures have been studied using X-ray powder diffraction (XRD) method, High resolution transmission electron microscopy images, scanning electron microscopy (SEM) micrographs, energy dispersive study and Brunauer-Emmett-Teller (BET) analysis. The TEM images of the final LTA zeolite annealed at 500 A degrees C revealed the formation of cubic structure. XRD analysis revealed that the crystallinity improved with annealing. BET analysis revealed that the synthesized LTA is a well crystallized 4A zeolite. LTA zeolites were dispersed in poly ethylene glycol in the ratio 3:100 and 5:100 and coated on porous alumina beads for the formation of membrane. The SEM images revealed excellent formation of fine structure LTA zeolite membrane with uniform coating. The membrane consisted of a top layer with thickness of 1.14-2.0 A mu m. Crystals in the top layer showed cubic morphology and amorphous phase was observed at the grain boundaries present between LTA zeolite and alumina substrate.