Porous alumina substrates as supports for zeolite membranes

Abstract

The application of zeolite membranes for the dehydration of chemical products such as alcohol has great potential to decrease the energy consumption and hence CO2 emission from chemical plants. In order to improve the performance of zeolite membranes, it is important to tailor-made the substrate support to suit the zeolite membrane material growth mechanism as well as to make the membrane system durable. Therefore, it is important to understand the influence of the porous ceramic support substrates in the zeolite membrane structure as well as in the final properties of the membrane. In this work, we evaluated chemical, mechanical and thermal properties of the supports, and examined their relationship to the performance of zeolite membrane. To systematically compare the properties of the porous alumina supports having different pore structures three different types of alumina porous supports, symmetric (NS-1, NS-2) and asymmetric (NA-1), were used in this study. The mean pore diameters of the symmetric porous alumina substrates were 150nm (NS-1) and 700nm (NS-2). The asymmetric porous alumina substrates (NA-1) were composed of a substrate with mean pore diameter of 700nm and top layer of mean pore diameter of 150nm. Surface properties including Zeta-potential values of the symmetric and asymmetric supports were evaluated in the pH range of 4 to 11. The values of zeta-potential were found to decrease with decrease in porosity at any given pH, and the point of zero charge of the supports were found shifted to lower pH range with decrease in porosity. Finally, Y-type zeolite membranes were synthesized on the porous alumina supports and had been evaluated for their H2O/IPA perm-selectivity. In this presentation, we will discuss the performance of such zeolite membranes in H2O/IPA separation.