A Novel, Low-Energy Stripper-Membrane Hybrid Process for Bioethanol Production

"Demand for ethanol as a gasoline supplement is surging. Just over 100 U.S.corn-toethanol plants are currently operating, with almost 40 new plants slated for completion in the coming year. By 2012, 250 bioethanol plants are expected to be installed. The current fermentation-distillation-molecular sieve process for ethanol production uses up to 20% of the energy content of the ethanol separated. Therefore, development of a lower-energy ethanol separation process is of considerable interest to bioethanol plant operators. This proposal describes a novel hybrid stripper-membrane separation process that could lower energy consumption of ethanol production by 45%. Achieving this goal requires the development of membranes with high water permeance that can remove water from ethanol solutions containing 50 wt% water at 100-130°C. Current water-selective membranes cannot be used with ethanol solutions containing more than 15 wt% water because of hydrolytic stability issues and excessive swelling. We have had preliminary success in developing the required membranes. Availability of these membranes would make radical changes to bioethanol separation flow schemes possible The objective of this program is to demonstrate membrane performance under simulated operating conditions, determine process feasibility, and set targets for pilot-scale development in a Phase II project."