Reduction of Distillation Usage in the Manufacture of Ethanol by Reactive Water Separation

Biomass-derived ethanol is now an integral part of the overall transportation fuel system in the U.S. To be useful as fuel grade ethanol, large amounts of water must be evaporated from dilute fermentation alcohol, a process that is energy-intensive, costly, and an impediment to the transition to a biofuels economy. By 2012, the total distillation energy required for water evaporation from dilute fermentation ethanol will approach 270 trillion BTU/yr. This project will demonstrate the technical feasibility of a novel reactive technology to reduce or substantially eliminate the reliance on distillation for water removal from biomass-derived ethanol. In this approach, a novel reagent will be added to the crude ethanol to convert the water into a highly volatile product, which is readily removed from the ethanol with a substantially reduced energy input. The reagent is then regenerated off-line by reversing the reaction and producing water, which is removed by simple decanting and phase separation. Phase I demonstrated that fuel-grade ethanol meeting commercial specifications could be produced by reactive dehydration. Phase II will entail optimizing the performance of the reactive dehydration catalysts for maximum energy savings. To facilitate early commercialization, the technology will be demonstrated through operation in a prototype unit. Commercial Applications and other Benefits as described by the awardee: The reactive dehydration system should find immediate application to the production of fuel-grade ethanol from biomass materials, saving at least 35 trillion BTU¿s in 2015 and resulting in annual cost savings of $700 million. Reactive dehydration also should be applicable to the production of many other industrial chemicals that require water removal, leading to opportunities for a major reduction in the energy requirements for dehydration in the production of chemicals and fuels for the U.S. economy