(7fv) Nanoporous Ultrathin Skinned Hollow Fiber Membranes

Chemical separations consume roughly 50% of U.S. industrial energy use, and molecularly-selective membranes can significantly reduce this number. Numerous membrane materials have emerged to address unmet separation challenges in the past two decades; however, large-scale membrane processes are still limited to a handful of applications. The capability to economically form selective materials into thin separation (skin) layers on scalable membrane geometry is key to enable large-scale application of ANY membrane process. Many challenging separations in the chemical and energy industry require highly-rigid nanoporous molecular sieves to achieve precise differentiation (<0.02 nm) of closely-sized molecules. These materials often have low permeabilities, and ultrathin skin layers must be formed to provide practical productivity.

During my Ph.D. at Georgia Tech with Professor Bill Koros, I built a framework to develop zeolitic imidazolate framework (ZIF)/polymer hybrid membranes for challenging separations. I designed hybrid membrane materials with unprecedentedly-high olefin/paraffin selectivity enhancements, which were translated to high-loading nanocomposite hollow fiber membranes with excellent scalability. My research also advanced the fundamental understanding of molecular diffusion in flexible ZIFs, and developed new avenues to create nanoporous ZIFs with tunable transport properties. Currently, I am expanding my portfolio by working on carbon molecular sieve membranes in collaboration with industry to address the challenges and opportunities involved with processing aggressive natural gas. My most recent work introduced ultraselective carbon molecular sieve membranes showing excellent separation performance for purification of supercritical natural gas.

My future program aims to lead the next revolution in molecularly-selective membranes by uniquely integrating highly-selective nanoporous molecular sieves with ultrathin skinned hollow fibers. These “nanoporous ultrathin skinned hollow fibers” represent a class of next-generation hollow fiber membranes comprising ultrathin skin layers relying upon rigid nanoporous molecular sieves. Design of rigid nanoporous materials with tunable transport properties will be guided by a molecular-level understanding of diffusion and material structure-property relationships. Economically-attractive module productivity is enabled by ultrathin skin layers and high packing density of the hollow fibers. With extensive experience in nanoporous materials and strong expertise in creating complex multi-layer composite hollow fibers, I am uniquely suited to undertake these challenging research efforts. The first-generation ultrathin skinned hollow fiber membranes will debottleneck separations of hydrocarbon vapor mixtures with significant energy savings, and enable membrane desalination of challenging feed water.

Teaching Interests:

Chemical Engineering Fundamentals, Mass Transfer, Separation Processes, Fundamentals of Membranes and Adsorbents

Selected Publications (18 total, 8 first author, 842 citations, H-index 11):

• Zhang, C.; Koros, W. J., Ultraselective carbon molecular sieve membranes with tailored synergistic sorption selective properties. Advanced Materials 2017, DOI: 10.1002/adma.201701631.
• Zhang, C.; Koros, W. J., Tailoring the transport properties of zeolitic imidazolate frameworks by post-synthetic thermal modification. ACS Applied Materials & Interfaces 2015, 7, 23407-23411.
• Zhang, C.; Zhang, K.; Xu, L.; Labreche, Y.; Kraftschik, B.; Koros, W. J., Highly scalable ZIF-based mixed-matrix hollow fiber membranes for advanced hydrocarbon separations. AIChE Journal 2014, 60, 2625-2635.
• Zhang, C.; Lively, R. P.; Zhang, K.; Johnson, J. R.; Karvan, O.; Koros, W. J., Unexpected molecular sieving properties of zeolitic imidazolate framework-8. The Journal of Physical Chemistry Letters 2012, 3, 2130-2134.
• Zhang, C.; Dai, Y.; Johnson, J. R.; Karvan, O.; Koros, W. J., High performance ZIF-8/6FDA-DAM mixed matrix membrane for propylene/propane separations. Journal of Membrane Science 2012, 389, 34-42.