Analysis of intensified sustainable schemes for biobutanol purification

Butanol is an alternative fuel with characteristics competitive to petroleum-based fuels. Compared with ethanol, butanol shows less miscibility, flammability, and corrosion; while potentially replacing gasoline in car engines without modifications. However, the production cost of butanol from renewables feedstock, i.e. bio-butanol (which also contains acetone and ethanol) through fermentation remains high. This is mainly due to the low yield of butanol in fermentation. The conventional recovery of butanol by distillation is an energy-intensive operation that has greatly restricted the industrial production of bio-butanol. This work studies ten hybrid and intensified configurations, based on the liquid-liquid extraction and dividing wall columns, to purify the butanol to the fuel grade. The study analyzes sustainability based on green metrics, including the inherent safety and control properties using singular value decomposition analysis. The results indicate that as long as the process is highly intensified, the sustainability and the inherent safety are improved and not necessarily the control properties. This is primarily due to the loss in the degrees of freedom in intensified processes.