(6jd) Microporous Molecular Sieves for Membrane and Adsorptive Separations

Separations take roughly half the overall energy consumption for chemical industry in the United States. Replacing traditional separation technology with membrane separation could save up to 90% of energy. The successful implementation of membrane separation strongly relies on developing suitable membrane materials and advancing of membrane fabrication techniques. Microporous molecular sieves, such as zeolites, metal-organic frameworks (MOFs), carbon molecular sieves et al., are promising membrane materials for a lot of energy and environment related separations with great industrial importance. The industrial applications of microporous molecular sieving membranes, however, are still quite limited. Two major impeding issues are: the membrane fabrication scalability and the fabrication cost. Membrane fabrication cost is a relative concept here. Less membrane area is needed for membranes with higher performance, i.e. higher permeance and selectivity. Therefore, higher performance membranes can afford to have higher fabrication cost per square meter of membrane area. A lot of efforts have also been on developing high performance membranes. Building upon my strong background on zeolite membranes and extended knowledge and experience on MOFs, hollow fiber spinning and simulated moving bed chromatography, I plan to work on following three areas for my future research.

• Cost-effective and scalable membrane fabrication method development

Hollow fiber membranes have much higher packing density than traditional disk and tubular membranes. They could significantly reduce membrane module size and overall membrane module cost. Recently, I have developed a scalable SSZ-13 zeolite hollow fiber membrane fabrication method and successfully synthesized 20 high-quality (CO₂ permeance ~5000 GPU, CO₂/C₃H₈ selectivity over 10,000) membranes together. Further development and fundamental understanding of membrane growth will be conducted towards industrialization and applicability to other types of molecular sieves.

• Advanced porous ceramic hollow fibers

Porous ceramic hollow fibers could be used as support for molecular sieving membrane fabrication or directly used for separation. Higher surface area will provide more effective area for membrane permeation is strongly preferred for membrane support. Current ceramic hollow fibers have a trade-off between surface porosity and mechanical strength. Through newly design hollow fiber structure and sophisticated hollow fiber spinning, I am targeting at a good balance between fiber mechanical strength and surface porosity. The hollow fibers could also find applications for air purification and water treatment et al. Hollow spinning and porous hollow fibers might also interest some professors working on catalysis and biology.

• Adsorptive separation with molecular sieves

Zeolites and MOFs show excellent adsorption selectivity for a lot of interesting gas and liquid mixtures. Application of zeolite/MOFs molecular sieves for pressure/temperature swing adsorption and chromatographic separation will be investigated. Special emphasis will be on transport related aspects, such as crystal size engineering, crystal immobilization, system pressure drop reduction. This work could be a good cooperation opportunity with other faculties interested in catalysis because tailored zeolite and MOFs are great catalysts, too.

Postdoctoral Projects: (1) Reactive Separations – Membrane Reactors for Olefin Production, Sponsor: Dow Chemical; (2) ZIF-8 Hollow Fiber Membranes for Propylene Separation, Sponsor: Department of Energy, Advanced Research Projects Agency – Energy (ARPA-E); (3) Hydrocarbon Separations with Simulated Moving Bed (SMB) Chromatography, Sponsor: ExxonMobil Corporation.

PhD Thesis: Ultramicroporous zeolite membranes for energy and environment related small molecule gas separation

Teaching Interests:

My teaching philosophy mainly concentrates on how to help students understand the concepts and principles with daily life examples and industrial applications. Building the connection will make the courses more attractive and engaging the students better. A filtration process as an example, we all know that water flow out slower and slower as debris clogs the sewage. Filtration process is very similar to that, how chemical engineers treat this problem and scientifically determine what to do and when? I hope my teaching could trigger students thinking more inside and outside class. More animation and videos will be used to help visualize things so that the contents are better delivered. I have solid background on chemical engineering courses and could teach Chemical Process Principles, Transport Phenomena, Kinetics and Reactor Design, Thermodynamics, Process, Product Design and Economics or their variation forms. Considering my research interests, I propose to develop an elective course for membrane separation. The course will cover various applications and many types of membrane materials, i.e. ceramic, polymer, zeolite, metal organic framework (MOF), carbon et al. I might also have small group of students to involve in projects in my labs and let them to get more in-depth learning in certain areas under lab research environment.

Teaching Assistant Experience: Equilibrium Processes, 2011; Heat Transfer, Basics, 2012; Process Dynamic Control, 2013; Materials & Energy Balance, 2014.

Mentoring experience: 3 PhD students in University of Cincinnati and 3 PhD students in Georgia Institute of Technology for fundamental knowledge, instruments, experiments and analysis.

Selected Publications:

1. S. Yang, Y. Chiang, S. Nair, Scalable One-Step Gel Conversion Route to High-Performance CHA Zeolite Hollow Fiber Membranes and Modules for CO2 and H2 Separations, Energy Technol. DOI: 10.1002/ente.201900494.
2. S. Yang, Y.H. Kwon, D.Y. Koh, B. Min, Y. Liu, S. Nair, Highly Selective SSZ‐13 Zeolite Hollow Fiber Membranes by Ultraviolet Activation at Near‐Ambient Temperature, ChemNanoMat, 2019, 5, 61-67.
3. S. Yang, A. Arvanitis, Z. Cao, X. Sun, J. Dong, Synthesis of Silicalite Membrane with an Aluminum-Containing Surface for Controlled Modification of Zeolitic Pore Entries for Enhanced Gas Separation, Processes, 2018, 6, 13.
4. S Yang, Z Cao, A Arvanitis, X Sun, Z Xu, J Dong. DDR-type zeolite membrane synthesis, modification and gas permeation studies, J. Membr. Sci. 2016, 505, 194-204.

5. S. Yang, J. Provenzano, Arvanitis, W. Jing, J. Dong, Effect of Precursor PH on DDR Zeolite Crystal Morphology in Secondary Growth Synthesis Using Sigma-1 Seeds and Reduced Organic Agents, J. Porous Mater. 2014, 21, 1001–1007.