Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
642942 | Separation and Purification Technology | 2010 | 7 Pages |
Abstract
ZSM-5 membranes were crystallized on tubular TiO2 supports and evaluated in the permeation of a 50%/50% 1-butene/i-butene mixture. If some of the water in the standard recipe 90 SiO2:0.225 Al2O3:1 Na2O:3.6 TPAOH:1.8 TPABr:1800 H2O was substituted by the same molar amount of short-chain length alcohol, the fluxes and permeances increased remarkably but the 1-butene/i-butene shape selectivity decreased only slightly. This experimental finding is attributed to additional non-zeolite micropores which are formed by the presence of alcohols in the synthesis batch. Since the formation of this additional pore system is linked to a decrease of the crystal size in the membrane layer, the increased length of grain boundaries could represent the structural origin of these additional non-zeolite pores. In a membrane preparation if 25% of the molar amount of water was substituted by ethanol, the 1-butene flux increased by the factor of two, but the mixture separation factor decreased by only 30%. Therefore, relatively thick ZSM-5 layers of about 30 μm gave 1-butene permeances of the order of 1 m3(STP) mâ2 hâ1 barâ1 with permselectivities of 20 and mixture separation factor of 6. The testing of the ZSM-5 membranes took place under practice-relevant conditions, i.e. with undiluted feeds and without applying sweep gases or reduced pressure on the permeate side.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Filtration and Separation
Authors
Hannes Richter, Hartwig VoÃ, Ingolf Voigt, Armin Diefenbacher, Gunter Schuch, Frank Steinbach, Jürgen Caro,