Reactive Extraction Process for Separating 2,3-Butanediol from Fermentation Broth

Separating 2,3-butanediol (BDO) from fermentation broth is challenging. Water is more volatile than BDO, so energy consumption for distillation is high. One alternative is a reactive extraction process. BDO in the broth reacts with an aldehyde or ketone to form an insoluble dioxolane, which can be decanted from the broth. The dioxolane is subsequently heated with water or steam, resulting in decomposition of the dioxolane into BDO and the aldehyde or ketone, which are separated to recover BDO and the aldehyde or ketone for recycling. Although variations of this process have been demonstrated, no information on efficiency, cost, or sustainability has been reported. Energy efficiency, cost, and sustainability of a reactive extraction process were evaluated. The total energy consumed by the reactive extraction process is about 17% of the net heating value of BDO, and the separation cost is $0.22/kg BDO.