Bioethanol Production with Mixed-Matrix Membranes

The separation and concentration of bioethanol from fermented biomass by distillation is a highly energy-intensive operation. In this project, ethanol-selective pervaporation membranes will be developed to perform this separation. The pervaporation process uses zeolite-polymer (mixed-matrix) membranes that provide ethanol separation factors two-to-three times higher than with distillation. By using these membranes, the energy consumption of bioethanol separation will be reduced by 30 to 50%. The construction of the separation plant would provide for further capital cost savings. In Phase I, mixed-matrix membranes were made and shown to have the permeances and selectivities required to provide significantly improved bioethanol separations. Membrane production was scaled up to the bench scale. A small spiralwound module was made and operated successfully. In Phase II, the membranes will be scaled up to the small industrial scale. Four-inch diameter modules with a membrane area of 4 m2 will be fabricated, tested, and optimized in the laboratory using pilot-scale equipment. A pilot plant will then be demonstrated to validate its reliability and efficiency. Commercial Applications and Other Benefits as described by the awardee: The simple flow scheme and low-maintenance operation should make this membrane process particularly applicable to small bioethanol plants such as cellulose-based bioethanol plants.