Study of Alcohol-Gasoline Separation Technology to Suppress Knock and Enable Higher Efficiency Engines

HONDA has investigated On Board Separation (OBS) of high octane alcohol and aromatics from current commercial fuels such as E10, a blend of 10 volume % ethanol and 90 volume % gasoline. The high-octane components concentrated from commercial fuel can be injected when needed to suppress knock. The availability of high octane fuel enables the engine to be designed with a compression ratio and boost which gives the Octane Boost Engine (OBE) higher efficiency. 3M has developed pervaporation separation modules made with flexible organic membranes that selectively remove and concentrate ethanol and methanol from gasoline blends. The separation module profile can be circular or rectangular to best fit the available space. Organic membrane performance has been studied for up to 15% ethanol and up to 15% methanol blended with 5% ethanol added for humid condition stability. Aromatic separation capability has also been evaluated. Performance stability has been evaluated for hundreds of separation hours. Module and membrane stability against thermal shock and vibration has also been evaluated. Test results show progress toward a commercially viable fuel separation system to boost fuel efficiency.