Bio-Butadiene Production from Raw Sugar (Aerobic Fermentation)

The process under analysis comprises three major sections: (1) Fermentation; (2) Fermentation broth treatment; and (3) Butadiene purification.

Fermentation. First, raw sugar is inverted to glucose and fructose. Then, the culture media used in the fermentation is prepared by mixing water, invert sugar, and nutrients in water. A genetically re-engineered yeast is propagated in an aerobic pre-fermentation step to obtain the proper inoculum concentration. The fermentation is carried out in fed-batch mode and under aerobic process conditions, in agitated fermenters equipped with internal coil. The fermentation step generates fermenter off-gas, which comprises the crude Butadiene product, and fermentation broth.

Fermentation broth treatment. After fermentation, cell biomass is separated from the fermentation broth. The clarified broth then is submitted to an ultrafiltration step, used to remove the remaining contaminants. The resulting aqueous stream may be discarded as waste water.

Butadiene purification. Initially, off-gas is compressed and cooled. The compressed gas is fed in a absorber column, where N-dodecane solvent absorbs the Butadiene. In the next column, In the Stripper Column, Butadiene is separated from the solvent. The recovered solvent is fed into a decanter for water removal before being recycled to first column. The Butadiene-containing stream is transferred into the Adsorption System. There, The oxygenates are removed by adsorption in adequate media. The oxygenate-free crude Butadiene is further purified in a last distillation column for heavy ends impurities separation. Butadiene with purity >99.7 wt% is recovered.