Preparation of higher flux NaA zeolite membrane on asymmetric porous support and permeation behavior at higher temperatures up to 145 °C in vapor permeation

NaA zeolite membranes were synthesized on an asymmetric porous alumina support with a lower mass-flow resistance for development of more economically feasible membranes with higher permeation performance. The support influence on permeation fluxes through the membrane using asymmetric support was investigated by vapor permeation at 100-145 degrees C in a mixture of water (10 wt.%)/ethanol (90wt.%) in which the higher permeation fluxes up to 37 kg m(-2) h(-1) or water permeances up to 3.2 x 10(-6) mol m(-2) S-1 Pa-1 at 145 degrees C were observed. The performance was higher than those in the previously reported NaA membrane on a monolayer porous alumina support of 31 kg m(-2) h(-1) or water permeances of 2.5 x 10(-6) mol m(-2) s(-1) Pa-1 145 degrees C. These results are experimental evidence to show the effect of asymmetric support utilization in membrane preparation on the higher membrane performance. The estimate of the pressure drop over the both types of support indicates that the improvement of higher permeation fluxes in the asymmetric type membrane could be attributed to the suppression of pressure drop in the support layer due to lower mass-flow resistance there. The water permeances are decreased at elevated temperatures, resulting in that the permeation flux cannot be increased linearly for the applied higher driving force of vapor pressure. The elevated temperatures are significant inhibition to the increasing of permeation fluxes through NaA zeolite membranes. (C) 2007 Elsevier B.V. All rights reserved.