Propane/propene permeation through Na-X membranes: The interplay of separation performance and pre-synthetic support functionalization

• Surface functionalization of the alumina support is crucial for membrane quality.
• Propane/propene gas separation performance is almost tripled.
• Surprisingly, Na-FAU shows higher transport for propane than propene.
• Ion exchange of the supported Na-FAU layer was not successful.

The influence of different pre-synthetic support modifications on membrane quality for paraffin/olefin and H2/CO2 separation has been investigated. It could be shown that when modifying the alumina support surface by agents like PDA (polydopamine) or APTES (3-aminopropyltriethoxysilane) as molecular linkers between the FAU layer and the alumina support, well intergrown dense membranes with less defects and, therefore, increased separation selectivities can be obtained. As model system, the propane/propene separation has been used. For binary mixtures at room temperature and 1 bar at both sides of the FAU membrane, the mixed gas separation factors of C3H8/C3H6 are found to be 3.3 for membranes grown on APTES and 2.0 for PDA functionalized supports in comparison to 1.4 for FAU membranes grown on the non-treated neat alumina supports. The improved FAU membrane quality when applying APTES and PDA for support modification in comparison with the neat untreated alumina support, has been proven for the separation of H2/CO2. Thanks to the relative thin FAU layers (3–4 μm), moderate fluxes can be obtained.

Figure optionsDownload as PowerPoint slide