Engineering-Oriented Design of the Separation Plant of the Catalytic Conversion Process of Bioethanol into Biobutanol

Biobutanol offers promise as a biofuel and platform chemical. Renewable butanol can be synthesized from bioethanol via the Guerbet reaction, in which higher alcohols are produced from short-chain alcohols. This research addresses the design and implementation of the separation system for the complex azeotropic mixture arising from ethanol-based biobutanol production. Using established conceptual design methods, an engineering-oriented approach was followed to deal with the numerous compounds present in the mixture and its complex phase behavior. To demonstrate the resulting design, a pilot plant composed of five distillation columns and two molecular sieves was constructed and operated. This plant constitutes the first experimental investigation of a separation system for this process. The recovery of unconverted ethanol was effectively demonstrated, and the production of high-purity butanol (∼99 wt %) was also achieved. From the experience of the construction and operation of the pilot plant, recommendations are given for industrial implementation of the separation system.