A global approach to obtain biobutanol from corn stover

The aim of this research was to subject corn stover to a complete biorefinery process at laboratory-scale in order to assess the production of biobutanol. The research was conducted to focus on process simplification, reduction of reagents and optimization of acetone-butanol-ethanol (ABE) fermentation. The main recommendations include the use of low acid concentrations during the physicochemical pretreatment, the selection of adequate Clostridium strains, detoxification of the hydrolysates with reusable adsorption resins and the possibility of performing gas stripping offline to recover ABE solvents. Various pretreatment conditions, fifteen bacterial strains and three polymeric adsorption resins were assessed. The proposed method consisted of a physicochemical pretreatment with 0.89% H2SO4 (w/w) at 160 degrees C during 5 min, followed by an enzymatic hydrolysis, which released 75% of the sugars contained in corn stover. The hydrolysate was detoxified with the resin Dowex (R) Optipore (R) SD-2 and fermented by C. saccharobutylicum DSM 13864, producing 4.75 +/- 0.25 g/L acetone, 9.02 +/- 0.11 g/L butanol and 0.39 +/- 0.01 gIL ethanol in 72 h, with a sugar consumption of 97.3 +/- 0.27%. A two-stage gas stripping was applied to the fermentation broth, obtaining butanol-rich condensates (418-425 g/L in the organic phase) in a total time of 6 h. (C) 2019 Elsevier Ltd. All rights reserved.