Towards Next-Generation Molecular Separations: Nanoporous Hollow Fiber Membranes

Chen Zhang, Georgia Institute of Technology, Atlanta, GA

13 July 2017 at 09:30

Location: ETB 535

Separations consume roughly 50% of U.S. industrial energy use, and molecularly-selective membranes can significantly reduce this number by retrofitting or replacing conventional, energy-intensive separation processes. Membranes have gained significant market share for desalination; however, extending membranes to olefin/paraffin separations and aggressive natural gas processing is more challenging. Nanoporous hollow fiber membranes have emerged as the leading candidates to enable large-scale separations in the petrochemical industries.

This talk will consider fundamental aspects of these exciting devices and discuss detailed examples of nanoporous hollow fiber membranes. The first example addresses propylene/propane separations using zeolitic imidazolate framework (ZIF)/polymer hybrid hollow fiber membranes. Analysis of transport in the dispersed ZIF particles and composite structure will be shown to provide a framework for membrane materials design. Characterizations and performance evaluation of hybrid dense film membranes with significantly enhanced propylene/propane separation performance will be shown to provide a useful platform for materials development. Next, formation of high-loading hybrid hollow fiber membranes with exceptional propylene/propane selectivity enhancement will be presented. The second example addresses processing of aggressive natural gas using carbon molecular sieve (CMS) hollow fiber membranes. Development of CMS hollow fiber membranes with un-precedentedly high carbon dioxide/methane selectivities will be discussed, again with a focus on fundamentals. Deconvolution of permeability data will be used to understand the respective kinetic and thermodynamic contributions to ultra-high membrane selectivities. Hypothetical structural evolution of CMS pore structures will be presented to explain substantially increased sorption selectivities in ultraselective CMS materials. Future research plans will be briefly overviewed.

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