Membrane technology for more efficient fuel
Polymer membranes have emerged as one of the fastest growing research areas today. Polymeric hollow fibre membranes are market driving high-performance products, said Prof Neal Chung, Department of Chemical and Biomolecular Engineering.
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| POWERING SINGAPORE: Fuel membrane technology for purifying natural gas may be the way to go with oil prices rising. Inset: Prof Neal Chung receiving an award from NUS President Prof Shih Choon Fong for his energy and dynamism, and contributions to research. |
Prof Chung, an international name in membrane science and engineering, leads a research team at NUS in this field. The team with Co-Principal Investigators Prof Hong Liang, Dr Jiang Jianwen, Prof William Krantz and Prof Raj Rajagopalan, is one of the six winners of the National Research Foundation’s inaugural Competitive Research Programme. The Programme offers a grant of $10 million for work which would impact on electronics, medicine and environmental technology.
"However, the field of membrane research for energy applications is only in its infancy. Current membrane technologies for hydrogen, natural gas and syngas are far from perfect. Breakthroughs in membrane materials research and engineering are needed," said Prof Chung. Syngas refers to synthesis gas, a combination of carbon monoxide, carbon dioxide, hydrogen and oxygen.
The team plans to conduct interdisciplinary research on membrane materials by integrating cutting-edge experimental methods and molecular simulations. "The outcome will guide the design and optimisation of novel membrane materials in a rational manner. The discovery of new materials and advanced fabrication technologies for clean-energy gas production is of utmost importance. It will lead to key technical innovation in clean energy production," said Prof Chung.
With oil prices climbing up rapidly, natural gas would be the primary energy source. However, there is a high content of carbon dioxide in natural gas, which if not separated, will not allow the gas to burn. Hydrogen sulphide has also to be separated from the gas or else it will corrode the pipelines. Hence, there is a race all over the world to come out with membrane technologies to remove unwanted components from natural gas.
Keeping ahead of the race, the team at NUS has already developed a new membrane that is of industrial capacity as it will not collapse when the pressure from the natural gas builds up. The team has also managed to cut cost of making such membranes by 95 per cent. There are still further hurdles to be overcome, of course. For example, membrane performance deteriorates because of plasticisation induced by carbon dioxide absorption.
"The challenge is to develop fine-enough materials that do not warp or change their properties when these gases pass through them," said Prof Chung.
"Our research team in NUS has synthesised new materials with superior gas separation performance and has fabricated novel membranes with different configurations to meet market demands. We have also been working with Mitsui (Japan) on new materials for gas separation," he said.
Membranes for kidney dialysis
Besides its application in helping to produce more efficient natural gas, membrane science also contributes to translational medicine. For example, membranes for kidney dialysis occupy about 43 per cent of the membrane market share. "Marketing analysis suggests that membranes for the purification and separation of proteins and pharmaceuticals have much higher growth rates and profit margins than membranes for water," he said.
However, the technology is still relatively immature with most reported data generated through trial and error, he added. Part of the reason for this is that conventional membranes designed for gas/liquid separation have poor chemical resistance and improper membrane structure. Incompatible physiochemical properties of the membranes and lack of functionalities to discern proteins and medicines, are also contributing factors. "We are working with Merck (USA) to remove organic solvents from syntheses of pharmaceuticals and BASF (Germany) on new membrane materials for kidney dialysis," said Prof Chung.
Membranes developed in NUS have been shown to be of superior separation performance. The team has filed about 20 patent applications on new membranes and have more than 150 journal papers published. Out of these, two patents were filed for new membranes for separating and recovering isopropanol (a solvent) from water and to remove toxic chromate from wastewater. A research collaboration has also been developed with Hyflux on membrane bioreactors.
"We believe that our research will help position Singapore as the most advanced membrane technology enterprise hub in the region," said Prof Chung.
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