For the production of highly concentrated bioethanol as an alternative fossil fuel, pevaporation, a membrane separation technique based on the use of an ethanol-selective membrane, has been a focus of research interest. In order to produce highly concentrated ethanol from a low-concentration ethanol solution containing succinic acid by pervaporation using an ethanol-permselective silicalite membrane, pervaporation performance was investigated. When supplying an ethanol solution containing succinic acid adjusted to pH>5, the pervaporation using a silicalite membrane double-coated with two types of silicone rubber exhibited no decrease in the performance. Also, using a silicalite membrane entirely covered with a silicone rubber sheet to prevent direct contact with succinic acid. No decrease in the ethanol concentration through the silicone rubber sheet-covered membrane was caused when supplying an ethanol solution containing succinic acid, not adjusted the pH.
