报告人：Dr. Winston Ho
Ph.D., Chemical Engineering, University of Illinois, Urbana, 1971；now, University Scholar Professor, in Department of Chemical and Biomolecular Engineering, Department of Materials Science and Engineering, The Ohio State University, USA.
Research Fields:
· Expert in molecularly based separations including definition of approaches, design of practical systems, scale-up and commercialization.
· Specialized in membranes and separations including polymer and liquid membranes, fuel-cell fuel processing and membranes, separations with chemical reaction, supported liquid membranes, reverse osmosis, gas treating, pervaporation, and facilitated transport.
Title:
New Fuel Cell Membranes
时间：7月24日上午9点
地点：教十～4115
欢迎有兴趣的老师和同学参加！
材料与化学工程学院
2007.7.22
The Seminar Abstract：
This presentation covers two types of new membranes for fuel cells: (1) carbon dioxide-selective membranes for hydrogen purification and (2) proton-exchange membranes (PEMs). On hydrogen purification for fuel cells, the membranes have been synthesized by incorporating amino groups into polymer networks. These membranes are selective to carbon dioxide and hydrogen sulfide preferentially versus hydrogen since the acid gases permeate through the amine-containing membranes via the facilitated transport mechanism due to their reversible reactions with the amine. The membranes synthesized have shown high carbon dioxide and hydrogen sulfide permeabilities and selectivities vs. hydrogen. Via carbon dioxide removal, results from water-gas-shift (WGS) membrane reactor experiments have shown carbon monoxide conversion/reduction to 10 ppm as well as significant hydrogen enhancement. The data have been in good agreement with modeling prediction. In another approach consisting of the CO2-selective membrane module followed by a conventional WGS reactor, the CO concentration was also reduced to < 10 ppm. Since hydrogen sulfide has much higher reaction rate with the amine than carbon dioxide, hydrogen sulfide can permeate through the membrane much faster than carbon dioxide. Our initial membrane data have shown hydrogen sulfide with about 3 times permeability of carbon dioxide. In addition, our initial experiments have shown a nearly complete removal of hydrogen sulfide from 50 ppm in the synthesis gas feed to about 10 ppb in the hydrogen product, which is good for fuel cell applications.
For high temperature PEMs, we have synthesized new six-member ring sulfonated polyimide (SPI) copolymers containing hydrophilic soft segments of oligomeric poly(ethylene oxide) to increase the water retention of the membranes at high temperatures and low humidities. The SPI copolymers exhibited improved thermal stability, and flexible free-standing membranes could be obtained. In fuel cell performance testing, the new membrane showed similar performance as Nafion® 112 at 70oC and 80% RH, but much better performance than Nafion® 112 at 120oC and 50% RH. Recently, we have also synthesized new sulfonated polybenzimidazole (SPBI)-based membranes. The membrane has exhibited a very high conductivity (> 0.1 S/cm) at high temperatures (> 120oC) and low humidities (even the anhydrous condition), which could essentially meet or exceed the DOE (Department of Energy) targets for PEM materials. In addition, this membrane has possessed excellent thermal, oxidative, chemical, and hydrolytic stability even at high temperatures. Thus, it has the great potential for the application in high temperature and low humidity PEMFCs. All of these new membranes should be much more cost-effective since the starting materials are more than two orders of magnitude less expensive than those for Nafion® membranes.
