Pervaporative separation and intensification of downstream recovery of acetone-butanol-ethanol (ABE)

The feasibility of pervaporative concentration of organic compounds from an ABE mixture to reduce the energy consumption of a downstream recovery unit was investigated. Firstly, an experimental investigation was done, using a polydimethylsiloxane (PDMS) membrane and a model solution of ABE as the feed. Different operating temperatures where investigated, with 40 °C showing the most favourable results. Secondly, the experimental results were utilised as the input for process simulations using Aspen Plus. Two ABE separation schemes were studied, one consisting of only distillation (conventional process) and one with an upstream pervaporation unit followed by an alternative distillation scheme. For the proposed pervaporative scheme, the butanol concentration after pervaporation was high enough so that it could be concentrated further at the beginning of the separation train through a liquid-liquid separation. The results of the simulations indicated that the conventional scheme was the most energy intensive and that the integration with an upstream pervaporation unit decreased energy consumption with 53%. The energy requirement for the distillation scheme was 33.3 MJ kg⁻¹ butanol, while that of the pervaporation-distillation scheme was 15.7 MJ kg^-1 butanol.