Preparation of ZSM-5 zeolite membranes by concentration variation with organic-free templates

Abstract

A new method of preparing ZSM-5 zeolite membranes on the outer surface of porous α-Al2O3 tubular by coating 15 nm ZSM-5 seeds without organic templates and then by varying-density synthesis with organic-free template sol-gel was investigated. A template-free nanosized ZSM-5 seeds and synthesis sol-gel of molar composition is 12Na2O: 100SiO2:2Al2O3:(2 500-5 000)H2O. XRD showed that the film was consisted of well-crystallized ZSM-5 zeolite. SEM investigation indicated that the zeolite films on the supports were defect free and the film thickness was approximately 5 μm. The permeation flux of H 2, N2 and CO2 0.894, 0.327 and 0.314 μmol·(m2·s· Pa)-1, respectively. The ideal selectivity of membrane for H2/CO2, H 2/N2 was 2.84, 2.73, respectively.