Sustainable bioalcohol production: Pretreatment, separation, and control strategies leading to sustainable processes

Alcohols produced by fermentation of biomass or biowastes are generally referred to as bioalcohols to clearly identify their green origin and to differentiate them from their oil-derived counterpart. Bioalcohols belong to the more general family of biofuels, and they can be employed in the transportation sector, like in the case of bioethanol and biobutanol, or used as building block chemicals like in the case of biomethane. However, different aspects of their production are still considered as a challenge. Recalcitrant structure of the feedstock used and the diluted mixtures obtained from fermentation together with complex thermodynamic behavior require efficient pretreatment methods, complex purification technologies, and suitable control strategies. These aspects are here discussed, emphasizing the achievements and the challenges. The purification of bioethanol by membrane separation and reactive distillation is considered as a case study in order to quantify the intensification procedure and analyze the process performances.