(637b) Perfluorinated Membranes for the Dehydration of Ionic Liquids for Processing Biomass

This presentation will discuss membrane dehydration of ionic liquids (ILs) with specific focus on biomass conversion to sugars. Ionic liquids can be used in the production of sugars from cellulosic biomass. Processing of the biomass requires mixing the IL with water. In many other potential applications, control of the water level in ILs is highly desirable since ILs are highly hygroscopic. The solvent power of ILs for processing biomass is highly dependent on their water content. Given the high cost of ILs, the wet ionic liquid must be dehydrated so it can be reused multiple times in the processing of biomass. CMS has developed chemically and thermally resistant pervaporation membranes that are effective in removing water from ionic liquids. Dehydration of ionic liquids by pervaporation using a hollow fiber composite perfluorinated membrane has been demonstrated. Efficient water removal is observed despite the low driving force for water permeation, e.g., low water activity coefficient. The water permeance is found to be approximately constant over a wide range of water concentration and temperatures. The permeation of ionic liquid through the membrane is negligible, which leads to extremely high water/IL separation factors and, therefore, minimal loss of IL. Results from both laboratory and pilot membrane dehydrators will be presented. The advantage of ionic liquids dehydration by pervaporation are discussed.