Zeolite NaA membranes supported on alumina hollow fibers: Effect of support resistances on pervaporation performance

Porous Al2O3 hollow fibers with different asymmetric macrostructures, i.e. single or double finger-like layer, have been prepared by a phase inversion/sintering technique. Such hollow fibers are used as supports to synthesize zeolite NaA membranes with high separation factors (>10,000) in the pervaporation of ethanol/water solution (90 wt%, 75 °C). Different zeolite thicknesses are achieved by means of extending the crystallization time and increasing the number of synthesis cycles. Influences of both the zeolite layer thickness and support layer macrostructures on pervaporation properties of zeolite NaA/Al2O3 supported membranes are investigated. The results indicate that variations of support macrostructures have a more noticeable effect on the pervaporation flux than zeolite layer thickness. There is an approximate linear dependence of the pervaporation flux of the supported membrane on the support porosity despite the fact that these hollow fibers are produced with different preparation conditions. When the support porosity increases to 69%, a pervaporation flux of 11.1 kg m−2 h−1 is achieved.