Optimization of corn stover biorefinery for coproduction of oligomers and second generation bioethanol using non-isothermal autohydrolysis

• Xylooligomers were obtained using non isothermal autohydrolysis.
• Solids with high susceptibility to enzymes were obtained.
• The conditions for xylooligomer and bioethanol production were compatible.
• Favourable substrate conversion and bioethanol concentration were obtained in fed-batch mode.

Corn stover was used for manufacturing 2nd generation bioethanol following a biorefinery scheme based on fractionation by autohydrolysis and further Simultaneous Saccharification and Fermentation (SSF) of pretreated solids. Autohydrolysis was performed under a wide range of severities to identify conditions leading simultaneously to a liquid phase containing hemicellulosic saccharides (accounting for up to 68% of initial xylan) and to a solid phase with high enzymatic susceptibility. SSF experiments were carried out under a variety of experimental conditions to assess the effects of the major operational variables. The glucan conversion into ethanol reached values up to 86%, with a bioethanol concentration of 37.8 g/L. Fed-batch operation in the SSF stage allowed the utilization of higher solid loadings, allowing an increase in the bioethanol concentration up to 51.6 g/L, or to reduce the amount of enzymes needed for reaching a given conversion.