(6im) Energy-Efficient Membrane-Based Separations

Separation of gas mixtures at the industrial scale in US accounts for 10-15% of national energy consumption. In this context membranes can effectively reduce the enormous amount of energy required for gas separations, compared to phase-change separation processes, such as cryogenic distillation. Despite of dominating gas separation membrane markets, current polymeric membranes suffer from a number of challenges, including plasticization and productivity-selectivity tradeoff, i. e., the Robeson upper bound. Pragmatically, how to translate the unique properties of membrane materials into practical conditions configured membrane products, like the hollow fiber membrane modules, remains another key challenge for membrane research.

During my graduate research in Prof. William Koros’s group, I addressed the challenges of CO2 induced plasticization and translation of high performance of ester-cross-linkable materials into hollow fiber membrane configuration. I developed ester-cross-linked hollow fiber membranes with enhanced plasticization resistance and permeance without sacrificing selectivity (P_CO2=120 GPU and CO2/CH4 selectivity=37 at 35 ^oC). I proved that ester-cross-linked hollow fibers are stable in against high-levels of moisture and hydrocarbon contaminants. I invented PDMC/Torlon^® composite hollow fiber membranes with capability of cutting the membrane material cost by 2/3. I proposed effective anti-aging approaches to mitigate the rapid permeance loss caused by physical aging. These studies enable a reliable translation of this advanced material into industrial relevant membrane products.

Beyond academic research, I exposed myself in an industrial setting by working as a Research Scientist for Air Liquide for over 4 years. This has broadened my horizon through engaging multiple R&D projects. I have become familiar with the hollow fiber membrane manufacturing process, including large-scale hollow fiber spinning, hollow fiber membrane bundle assembling and post-treatment. I have seen the whole picture of modern membrane formation process from different angles. The perspectives I gained in the industry are essentially useful to guide future membrane researches.

Currently, I am expanding my research territories by studying membranes for gas separations and water treatment in Dr. Jeffrey Urban group at Lawrence Berkeley National Laboratory. The Mixed Matrix Membrane (MMM) technique can produce membranes with performance beyond the upper bound limit. However, the interphase between the polymer phase and inorganic dispersant phase in MMMs tends to form non-selective micro-voids defects. I developed membranes surpassing the current upper bound and mitigating the interfacial defects and percolation limitation in MMMs. Besides gas separation, I also devote to membrane research for water treatment, like forward osmosis desalination, which reshapes my membrane research portfolio.

Research Interests:

My future research interests are developing advanced membranes for energy efficient separations, including gas separation and water treatment. The primary goal of my research is to push limits of current membrane technology via creating new membrane materials and scalable membrane formation process. Theoretically, understanding the molecule transport mechanisms in membranes is needed to guide the design of membrane materials with tunable functionalities. Experimentally, synthesis and characterization of new polymer and hybrid composites are crucial to fabricate membranes with desirable performance. Technically, developing scalable membrane formation techniques, such as hollow fiber spinning, are the requisite for commercializing membrane technologies.

Teaching Interests:

Fundamentals of Chemistry and Chemical Engineering, Mass Transfer, Membranes Separation etc.

Selected Publications (11 total, 8 first author):

1. C. Ma and W. J. Koros, “Physical aging of ester-cross-linked hollow fiber membranes for natural gas separations and mitigation thereof”, J. Membr. Sci., 551 (2018) 214-221
2. C. Ma and J. J. Urban, “Polymers of Intrinsic Microporosity (PIMs) Gas Separation Membranes: a mini Review”, Proc. Nat. Res. Soc., 2 (2018) 1-19 (Invited review)
3. C. Ma et al., “Thin-skinned intrinsically defect-free asymmetric mono-esterified hollow fiber precursors for crosslinkable polyimide gas separation membranes’, J. Membr. Sci., 493 (2015) 252-262
4. C. Ma and W. J. Koros, “Effects of hydrocarbon and water impurities on CO₂/CH₄ separation performance of ester-crosslinked hollow fiber membranes”, J. Membr. Sci., 451 (2014) 1-9
5. C. Ma and W. J. Koros, “Ester-crosslinkable composite hollow fiber membranes for CO₂ removal from natural gas”, Ind. Eng. Chem. Res. 2013, 52 (31) 10495–10505 (Invited paper in honor of Prof. Enrico Drioli)
6. C. Ma and W. J. Koros, “High-performance ester-crosslinked hollow fiber membranes for natural gas separations”, J. Membr. Sci., 428 (2013) 251–259

Selected Patents (9 total, 2 granted):

1. Composite hollow fiber membranes useful for CO₂ removal from natural gas, US patent publication date 2017/8/1, patent number US9718031 B2 (Granted)
2. A direct bonding method for shortwave light auxiliary silicon slice, CN patent publication date 2009/12/23, CN patent number CN100573821C (Granted)
3. Functionalized Metal-organic frameworks/polymer mixed matrix membranes, US patent filed date 2018/3/16, application number US 62/643,867
4. Metallopolyimide precursor fibers for aging-resistant carbon molecular sieve hollow fiber membranes with enhanced selectivity, US patent publication date 2018/1/4, application number US15/199,902
5. Defect-free carbon molecular sieve membranes with enhanced selectivity and aging resistance and the method of making the same, US patent publication date 2016/12/22, application number US 15/253,497
6. Composite carbon molecular sieve membranes having anti-substructure collapse particles loaded in a core thereof, US patent publication date 2016/6/2, application number US14/827,064