Bioethanol Production with Mixed-Matrix Membranes

The cost-effective production of ethanol would have major implications for U.S. energy independence. Distillation, the conventional process for the production of ethanol, is not cost-effective for small-waste biomass streams. The development of more selective ethanol-permeating membranes could lower capital and energy costs and improve economic feasibility. This project will develop an integrated, pervaporation-dephlegmation membrane process to separate ethanol from fermentation broth and produce dry ethanol. In particular, high-selectivity, mixed-matrix zeolite-polymer membranes will be developed for the pervaporation step. In previous work, mixed-matrix membranes were prepared, which provided ethanol/water separation factors of 20-24 ¿ three times greater than the best polymeric membrane. In Phase I, additional and improved, composite mixed-matrix membranes will be made, and their performance will be evaluated in laboratory tests. A technical and economic analysis of the total process using these membranes will be performed, in order to demonstrate feasibility and set targets for Phase II. Commercial Applications and Other Benefits as described by the awardee: The pervaporation-dephlegmation process should allow a large number of small (20-100 tons per day) waste biomass streams to be economically converted to ethanol. Such streams are produced in cheese, wine, beer and sugar production. Distillation is too expensive to use at this scale. Nationwide, more than 200 plants might be installed. As the technology develops, it could have application to more mainstream bioethanol production applications