On Board Dimethyl Ether Generation to Assist Methanol Engine Cold Starting

Dimethyl ether has high vapor pressure and wide flammability limits, which make it an excellent fuel for cold starting methanol engines. We have investigated the catalytic dehydration of methanol to produce dimethyl ether on board methanol-fueled vehicles. We tested four methanol dehydration catalysts in a microcatalytic plug flow reactor and found that a fluorinated γ-alumina was very active and selective for methanol dehydration in the 250-350°C (482-662°F) temperature range. We also tested the fluorinated γ- alumina catalyst with a 15% gasoline/85% methanol mixture (M85) and found that the catalyst activity decreased in proportion to the gasoline content but that no catalyst deactivation occurred. Data from the catalyst testing were used to design an electrically-heated methanol dehydration reactor ‘that could be used on board a methanol fueled vehicle.